U-boat Archive - Type XB Manual

Page II	U-boat Information	U-Boat Type XB

	Amendments

Note the section, page and paragraph No., to which changes or additions are registered:			Certified to be Correct

Page	Contents	Paragraph No.		Place	Date	Signed

U-Boat Type XB	U-boat Information	Page III

	Table of Contents

Table of Contents

Chapter A: Ship's Information

I.	General				Page:
	1)	Shipyard information			1
	2)	Principal measurements			1
		a)	Dimensions		1
		b)	Measured displacement		2
		c)	Volume and distance from center of mass		3
			1.	Interior rooms	3
			2.	Exterior spaces	4
			3.	Ballast tanks, main ballast and reserve fuel oil tanks, supply and collecting tanks.	6
			4.	Total volume	7
		d)	Test and operating pressures		7
		e)	Materials		10
		f)	Weights		11
		g)	Stability		11
	3)	Weapons overview			14
	4)	Safety and rescue equipment overview			14
		a)	Structural safety installations		14
		b)	Safety equipment		15
		c)	Rescue equipment		15
	5)	Test data			16
		a)	Speed [surfaced] and [submerged]		16
		b)	Diving time		16
		c)	Pressure dock trials		17
		d)	Depth differences for bow and stern		17
	6)	Practical values			19
		a)	Speeds for various operating conditions		19
		b)	Behavior of the boat under different rudder angle and wind conditions		19
		c)	Turning circles		20
		d)	Behavior in a seaway		22
		e)	Diving characteristics		22
		f)	Depth control		23

Page IV	U-boat Information	U-Boat Type XB

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				Page:
		g)	Vibrations	25
		h)	Sound levels	26

II.	Boat and pressure hull - including through-hull openings.			29
	1)	General construction of the boat		29
	2)	Construction of the pressure hull		30
	3)	Partitioning of the pressure hull		30
	4)	Conning tower structure		33
	5)	Openings in the pressure hull		34
	6)	Construction of the outer shell		35
	7)	Partitioning of the outer shell		37

III.	Diving installations.			38
	1)	Tanks and fuel oil tanks		38
		a)	Main ballast tanks	38
		b)	Main ballast and reserve fuel oil tanks	38
		c)	Bow and stern buoyancy tanks	38
		d)	Regulating tanks and regulating and reserve fuel oil tanks	39
		e)	Trim tanks	40
		f)	Negative buoyancy tanks	41
		g)	Torpedo compensating tanks	41
		h)	Mine compensating tanks	41
	2)	Blowing and exhaust gas blowing installation		42
		a)	Compressed air blowing	42
		b)	Exhaust gas blowing	42
	3)	Venting and vent valves		43
	4)	Compressed air systems		45
		a)	Air compressors	45
		b)	High pressure compressed air flasks	45
		c)	Compressed air equipment	46
	5)	Pumps		47
	6)	Dive planes		47

IV.	Armament.			48
	1)	Mine installations		48
	2)	Torpedo installations		49
		a)	Torpedo tubes	49

U-Boat Type XB	U-boat Information	Page V

	Table of Contents

				Page:
		b)	Stowage	49
		c)	Torpedo loading equipment	49
		d)	Torpedo fire control system	50
		e)	Weight compensation	51
		f)	Charging and heating the electric torpedoes	52
	3)	Gunnery		53
		a)	Weapons	53
		b)	Ammunition	53
	4)	Demolition equipment		54
	5)	Small arms		54

V.	Communications.			55
	1)	Visual and acoustic equipment		55
	2)	Electronic communication equipment		56
		a)	Radio installation	56
		b)	UT [Underwater Telegraphy] installation (sound)	56
		c)	Reporting and broadcast system	57
		d)	Ultra short wave gear	58
	3)	Direction finding and listening equipment		58
		a)	Radio direction finder	58
		b)	K.D.B. installation	59
		c)	G.H.G. installation	59
		d)	Nah S installation [active sonar to detect mines]	59
	4)	Power supply for electronic communications equipment		59
	5)	Aerials		60

VI.	Steering system and anchor installations.			62
	1)	Steering system		62
		a)	Main rudder installation	62
		b)	Dive planes installation	64
	2)	Anchor installation		65

VII.	Equipment and installations for navigation.			66
	1)	Ship control		66
	2)	Periscopes		66
		a)	Attack periscope (aft conning tower periscope)	67
		b)	Night attack periscope (forward conning tower periscope)	67
		c)	Control room periscope	67

Page VI	U-boat Information	U-Boat Type XB

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				Page:
		d)	Periscope drive	67
	3)	Compass installation		68
		a)	Gyro-compass	68
		b)	Projector compass (magnetic compass)	69
	4)	Signal equipment		69
	5)	Depth sounding equipment		69
		a)	Echolot	69
		b)	Elektrolot	70
		c)	Hand lead	70
	6)	Log installation		70
	7)	Alarm installation		70
	8)	Ordering and reporting installations		71

VIII.	Safety and rescue installations.			76
	1)	Installations for submerged and surfaced boat		76
		a)	Emergency lighting	76
		b)	Hand lamps	76
		c)	Fire extinguishers	76
		d)	Flooding installation	77
		e)	Drainage installation	77
		f)	UT installation	77
		g)	Emergency steering gear	77
		h)	Emergency escape gear and diving suit	77
		i)	Life rafts and mats	77
		k)	Damage control materials	77
	2)	Installations for surfaced boat		78
		a)	Battery ventilation	78
		b)	Emergency vent valves	78
		c)	Coaming	78
		d)	Life buoy, night signal buoy and dinghy	79
		e)	Life jackets	79
		f)	Railing and tethers	79
		g)	Inflatable boat	79
	3)	Installations for submerged boat		79
		a)	Compartmentation	79
		b)	Air purification system	80
		c)	Compressed air and emergency blowing manifold	81
		d)	Emergency air supply system	81

U-Boat Type XB	U-boat Information	Page VII

	Table of Contents

				Page:
		e)	Air trap	82
		f)	Net deflector	82
		g)	Net cutter	82
		h)	Compartment ready indicating system	82
		i)	Hull closure indicating system	82
		k)	Vent valve indicating system	83

IX.	Damage control.			84
	1)	General		84
		a)	Damage control parties	84
		b)	Balancing the boat	84
		c)	Reserve buoyancy	85
	2)	Weights and trim adjustment with water flooding		85
		a)	Leakage into external tanks with the boat surfaced	85
		b)	Leakage into pressure hull with the boat surfaced	87
		c)	Leakage into external tanks and into pressure hull with the boat surfaced	89
		d)	Leakage with the boat submerged and with the boat lying on the bottom	95
	3)	Leakage counter measures		95
		a)	Blowing	95
		b)	Sealing the compartments	96
		c)	Sealing leaks	96
		d)	Pumping	98
		e)	Weight relief	98
	4)	Escape from a sunken boat		98
		a)	Escape procedures	98
		b)	The flooding of the boat and effects on the crew	99
		c)	Escaping from the boat	101
		d)	Flooding options	102
	5)	Gas hazard		106
	6)	Fire hazard		106
	7)	Fire extinguishing equipment and flooding installation		106
	8)	Drainage and compressed air systems		106

Page VIII	U-boat Information	U-Boat Type XB

	Table of Contents

Chapter B: Machinery Installations

					Page:
I.	Propulsion plant				107
	1)	G.W. diesel engine installation			107
		a)	General and performance figures		107
		b)	Construction of the propulsion plant		107
		c)	Auxiliary machinery		107
			1)	Supercharger	107
			2)	Pumps	108
			3)	Governor	108
	2)	Battery			108
		a)	Technical and performance data		108
		b)	Construction and maintenance		109
		c)	Capacity, discharging, final voltage		110
		d)	Charging		110
	3)	The main switchboards and battery connections			111
	4)	E motor installation			111
		a)	General and performance data		111
		b)	Motor construction and connections		112
		c)	Auxiliary machinery		112
	5)	Shaft lines			113
		a)	Propellers		113
		b)	Drive shafts, bearings and shaft brakes		113
		c)	Main thrust bearing		114
		d)	Clutches		114
	6)	Interaction of the engines and motors			115
		a)	General		115
		b)	Diesel engine only drive		115
		c)	E motors only		115
		d)	Support and buffer mode		115
		e)	Charging operation		116
		f)	Diesel-electric drive		116

II.	Auxiliary machinery for propulsion				117
	1)	Ship's auxiliary machinery			117
		a)	Main rudder and diving planes		117
		b)	Anchor and warping capstan installation		117

U-Boat Type XB	U-boat Information	Page IX

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				Page:
		c)	Air compressor	118
		d)	Auxiliary drain and trim pump	119
		e)	Main drain pump	119
		f)	Auxiliary drain pump 1 and 2	120
		g)	Intake and exhaust air fan	120
		h)	Battery ventilation fan	120
		i)	Pressure oil pump	121
		j)	Periscope drive	121
		k)	Refrigeration plant	121
		l)	Compartment ventilation installation	123
		m)	Distilling unit	123
		n)	Hand pumps	123
		o)	W.C. installation	124
		p)	Gyro compass installation	124
		q)	Circulating fan for air purification system	124
	2)	Auxiliary machinery for the diesel engine installation		124
		a)	Auxiliary lubricating oil pump port and starboard	124
		b)	Hand lubricating oil pump	124
		c)	Fuel oil feed pump	125
		d)	Hand dirty lubricating oil pump	125
		e)	Auxiliary cooling water pump	125
		f)	Hand cooling water pump	125
		g)	Lubricating oil purifier	125
	3)	Auxiliary machinery for the E installation		125
		a)	E motor fan blower	125
		b)	E motor room cooling pump	126
		c)	Bearing lubricating oil cooling installation for the E motors	126

III.	Draining and flooding			127
	1)	Main drainage installation		127
	2)	Auxiliary drainage installation		127
	3)	Hand drainage installation		128
	4)	Artificial flooding installation		128
	5)	Natural flooding installation		128

Page X	U-boat Information	U-Boat Type XB

	Table of Contents

					Page:
IV.	Sea, wash, and fresh water installations				129
	1)	Sea water installation			129
	2)	Wash water installation			129
	3)	Fresh water installation			131
	4)	Waste water installation			131

V.	Ventilating systems				132
	1)	Boat ventilation			132
	2)	Battery ventilation			133
	3)	Additional ventilation for air purification while running at silent speed			134

VI.	Heating installation				135
	1)	Steam heating			135
	2)	Electric heating			136
	3)	Steam generating installation			136

VII.	Lubricating oil installation				137

VIII.	Fuel oil installation				139

IX.	Electrical installation				141
	1)	E motors			141
	2)	Batteries			141
	3)	Main switchboards			141
	4)	Auxiliary switchboards and power distribution			141
	5)	Electric equipment (table)			142
		a)	E drive motors and their current draw		142
		b)	Rotary converters and associated equipment		142
			1.	Gyro compass converter (2 unit)	142
			2.	Communications equipment converter	143
			3.	UT converter	144
			4.	Depth sounding converter	144
			5.	Rotary amplifier for the gyro angle setting gear	145
		c)	Ordering and reporting installations		146
			1.	General information and power supply	146
			2.	Engine order telegraph system	146
			3.	Shaft revolution indicator system	147
			4.	Rudder order telegraph and rudder angle indicator system	147
			5.	Diving planes angle indicator system	148

Page XI	U-boat Information	U-Boat Type XB

	Table of Contents

			Page:
	6.	Alarm bell and flashing light system	148
	7.	Compartment ready indicating system	149
	8.	Hull closure indicating system	149
	9.	Vent valve indicating system	150
	10.	Torpedo fire control and orders indicator system	151
	11.	Shaft mine launching reporting installation	151
d)	Signal equipment		152
	1.	General	152
	2.	Running lights	152
	3.	Searchlight equipment	153
e)	Electric welding equipment		154

Chapter C.

Appendix.		Enclosure
1)	Boat's silhouette	1
2)	Installations plan (Horizontal section)	1
3)	Installations plan (Length section with height scale)	1
4)	Tanks arrangement	1
5)	Trim table	1
6)	Ballast tank flooding and venting installation, exhaust gas blowing and diver emergency blowing equipment	1
7)	Blowing and emergency blowing equipment, piping for pressurizing regulating tanks	1
8)	Compartment and battery ventilating systems	__1__
		8

-.-.-.-.-.-.-.-.-.-

U-Boat Type XB	A. Ship Information	Page 1

U-boat Information	I. General	1

A. Ship's Information.

I. General.

Shipyard information.

Construction yard:

Fried. Krupp Germaniawerft A.G., Kiel - Gaarden


U-boat No.	Construction yard	Keel laying	Launching	1st Commissioning	Decom-missioning	2nd Commissioning

U-116	GW	27.11.39	3.5.41	26.7.41
U-117	GW	27.11.39	26.7.41	25.10.41
U-118	GW	1.3.40	23.9.41	6.12.41
U-119	GW	15.11.40	6.1.42	18.4.42
U-219	GW	31.5.41	6.10.42	12.42
U-220	GW	16.6.41	23.2.43	5.43
U-233	GW	15.8.41	29.6.43	9.43
U-234	GW	1.10.41	28.9.43	12.43

Principal measurements. (ship's construction)

Dimens'ions. (See Secret Military document)

Length:
Length overall	m
Length at the waterline	m
Length of the pressure hull with end caps	m
Length of pressure hull without end caps	m

Width:
Maximum width	mm
Maximum width at the waterline	mm
Maximum width of the pressure hull	mm
Diameter of the forward end of the pressure hull	mm
Diameter of the aft end of the pressure hull	mm

Page 2	A. Ship Information	U-Boat Type XB

2	I. General	U-boat Information

Draft:
Draft aft		m
Draft amidships		m
Draft forward		m
Length of pressure hull without end caps		m
Note: For length, width, and draft see Secret Military document.

Height:
Upper deck above keel	6535	mm
Top of conning tower above keel	10100	mm
Top of attack periscope and air search periscope above conning tower fairing	5036	mm
Top of control room periscope and air search periscope above conning tower fairing	2145	mm
Extended air search periscope above keel	15136	mm
Extended control room periscope above keel	12245	mm

Conning tower and keel:
Height of conning tower above pressure hull	2427	mm
Length of the conning tower	3460	mm
Width of the conning tower	2080	mm
Height of the keel	900	mm
Width of the keel	2200	mm
Length of straight keel	50800	mm

Measured displacement.

Surfaced displacement		m³
Submerged displacement		m³
Official displacement		m³

U-Boat Type XB	A. Ship Information	Page 3

U-boat Information	I. General	3

Volume and distance from center of mass.

1) Interior rooms:


Designation	Location	Volume	Total volume m³	Distance / meters

Aft torpedo room	Room 1, Comp. 1		75.00	- 28.80
E motor room	Room 2)	95.00		- 20.75
Diesel engine room	Room 3) Comp. II	153.00	347.00	- 12.00
Galley and petty officers room	Room 4)	99.00
of this:
Petty officers room + galley		70.00
Battery room 1		29.00
Control room	Room 5, Comp. III		100.00	+ 4.95
of this:
Munitions magazine		27.00		+ 6.10
Nah sonar room		4.00		+ 8.55
Living room	Room 6, Comp. IV		175.00	+ 14.50
of this:
Provision room		18.00
Battery room 2		27.00
Crew room		17.00
Remainder of room		113.00
Forward mine room	Room 7, Comp. V		115.00	+26.40
		Total:	812.00

Page 4	A. Ship Information	U-Boat Type XB

4	I. General	U-boat Information

2) Exterior spaces:

[translators note: A frame = outer hull frame D frame = pressure hull frame]


	From	Location		Volume	Distance
Designation	Frame - Frame	Stb. Port		meters³	meters

Main ballast tank 1	A -9 - +8			44.30	- 34.75
Main ballast and RFO 2 port	A 8 - 24		port)	43.25	- 26.92
Main ballast and RFO 2 stb.	A 8 - 24	stb.	)	43.25	- 26.92
Main ballast and RFO 3 port			port)	58.20)	- 20.27
Main ballast and RFO 3 stb.	A 24 - 34	stb.	)	58.20)	- 20.27
Fuel oil tank 1a port	A 34 - 43		port)	83.2	- 15.40
Fuel oil tank 1a stb.	A 34 - 43	stb.	)	83.3	- 15.40
Main ballast tank 4 port)	A 43 - 53		port)	78.40)	- 10.43
Main ballast tank 4 stb.)	A 43 - 53	stb.	)	78.40)	- 10.43
Main ballast tank 5 port)	A 53 - 63		port)	88.95)	- 29.87
Main ballast tank 5 stb.)	A 53 - 63	stb.	)	88.95)	- 29.87
Regulating and RFO tank 1 port)	D 41-1/2 - 43-1/2		port	16.85)	- 0.60
Regulating and RFO tank 1 stb.)	D 41-1/2 - 43-1/2	stb.		16.85)	- 0.60
Regulating tank 2 port)	D 45 - 48		port	13.30)	+ 2.11
Regulating tank 2 stb.)	D 45 - 48	stb.		13.30)	+ 2.11
Mine compensating tank 1)	D 41-1/2 - 43-1/2	stb.		7.55)	- 1.24
Mine compensating tank 2)	D 41-1/2 - 43-1/2		port	7.55)	- 1.24
Mine compensating tank 3)+	D 43-1/2 - 45-1/2	stb.		7.55)	+ 0.54
Mine compensating tank 4)+	D 43-1/2 - 45-1/2		port	7.55)	+ 0.54
Negative buoyancy tank port)	D 45-1/2 - 48		port	7.85)	+ 2.36
Negative buoyancy tank stb.)	D 45-1/2 - 48	stb.		7.85)	+ 2.36
Main ballast tank 6 port)	A 73 - 83		port)	88.20)	+ 6.04
Main ballast tank 6 stb.)	A 73 - 83	stb.	)	88.20)	+ 6.04
Main ballast tank 7 port)	A 93 - 99		port)	75.75)	+ 11.52
Main ballast tank 7 stb.)	A 93 - 99	stb.	)	75.75)	+ 11.52
Fuel oil tank 2a port)	A 93 - 99		port)	54.9	+ 15.86
Fuel oil tank 2a stb.)	A 93 - 99	stb.	)	55.2	+ 15.86

Mine compensating tanks 3 and 4 can be used as spare wash water tanks.

U-Boat Type XB	A. Ship Information	Page 5

U-boat Information	I. General	5

Exterior spaces (continued)


	From	Location		Volume	Distance
Designation	Frame - Frame	Stb. Port		meters³	meters

Main ballast and RFO tank 8 port	A 99 - 109		port)	69.05	+ 19.72
Main ballast and RFO tank 8 stb	A 99 - 109	stb.	)		+ 19.72
Main ballast and RFO tank 9 port	A 109 - 128		port)	33.77	+ 26.76
Main ballast and RFO tank 9 stb.	A 109 - 128	stb.	)	33.77	+ 26.76
Main ballast tank 10	A 128 - 147			39.00	+ 36.36
Stern buoyancy tank	A -16 - -9			8.40	- 40.42
Bow buoyancy tank	A 128 - 152			28.00	+ 37.63

Page 6	A. Ship Information	U-Boat Type XB

6	I. General	U-boat Information

3. Ballast tanks, fuel oil tanks, tanks and storage: (Ordered from aft to forward)


Designation	Location	From	Volume in	Distance in
Designation	Location	Frame - Frame	meters³	meters

Trim tank 1	stb.	D 7 - 11	3.940)	- 27.52
Trim tank 2	port	D 7 - 11	3.940)	- 27.52
Torpedo compensating tank 1	stb	D 11 - 13-1/2	3.240	- 25.04
Torpedo compensating tank 2	port	D 11 - 13-1/2	3.920	- 24.90
Waste water tank 1	stb.	D 12-1/2 - 13-1/2	0.760	- 24.33
Alkali tank	port	D 14 - 15	0.063	- 23.49
Water distillate tank 1	center	D 18-1/2 - 21	0.195	- 20.06
Water distillate tank 2	center	D 18-1/2 - 21	0.580	- 19.49
Water distillate tank 3	port	D 86 - 87	0.200	+ 33.15
Fuel oil gravity feed tank	center	D 26 - 28	2 x 600	- 13.33
Dirty lubricating oil tank	center	D 24 - 26	1.360	- 15.09
Lubricating oil collecting tank stb.	center	D 28 - 30	1.360	- 11.89
Lubricating oil collecting tank port	center	D 26 - 28	1.360	- 13.49
Fuel oil collecting tank	center	D 30 - 31	0.680	- 10.69
Waste water tank 2	center	D 34 - 35-1/2	0.625	- 7.30
Fresh water tank 1	center	D 35-1/2 - 36-1/2	0.780	- 6.47
Wash water daily supply tank	port	D 36-1/2 - 37-1/2	0.060	- 5.69
Lubricating oil supply tank 1	stb.	D 35-1/2 - 41	3.900	- 4.43
Lubricating oil supply tank 2	port	D 35-1/2 - 41	3.900	- 4.43
Lubricating oil supply tank 3	stb.	D 41 - 45-1/2	4.200	- 0.39
Lubricating oil supply tank 4	port	D 41 - 45-1/2	4.200	- 0.39
Fresh water tank 2	port	D 49 - 49-1/2	0.230	+ 4.23
Hydraulic oil supply tank	stb.	D 47-1/2 - 49-1/2	1.250	+ 3.24
Fresh water tank 3	stb.	D 58 - 61	2.000	+ 11.71
Fresh water tank 4	port	D 58 - 58-1/2	0.830	+ 10.79
Wash water tank 1	port	D 61 - 62	0.850	+ 13.31
Waste water tank 4	port	D 70-1/2 - 72	0.780	+ 21.18
Wash water tank 2	port	D 72 - 73	0.610	+ 22.11
Mine compensating tank 5	stb.	D 74 - 77	3.650)	+ 24.38
Mine compensating tank 6	port	D 74 - 77	3.650)	+ 24.38
Mine compensating tank 7	stb.	D 77 - 80	2.250)	+ 26.75
Mine compensating tank 8	port	D 77 - 80	2.250)	+ 26.75
Trim compensating tank 3	stb.	D 87 - 89	3.780)	+ 34.45
Trim compensating tank 4	port	D 87 - 89	3.780)	+ 34.45

U-Boat Type XB	A. Ship Information	Page 7

U-boat Information	I. General	7

4. Total volume.

Main ballast tanks	414.60	m³
Main ballast and reserve fuel oil tanks	238.05	m³
Main ballast and main ballast and reserve fuel oil tanks	652.65	m³
Fuel oil tanks 1a port and stb., 2a port and stb.	138.1	m³
Fuel oil tanks, main ballast and reserve fuel oil tanks, and regulating and reserve fuel oil tanks	409.75	m³
Lubricating oil supply tanks 1, 2, 3 and 4	16.00	m³
Lubricating oil collecting tanks port and stb.	2.72	m³
Lubricating oil, total	18.72	m³
Fresh water tanks, total	3.010	m³
Wash water tanks, total	16.320	m³
Waste water tanks	2.985	m³
High pressure compressed air flasks at 205 kg/cm²	12.47	m³
Oxygen flasks at 160 kg/cm²	0.800	m³
Main ballast tanks, main ballast and reserve fuel oil tanks, fuel oil tanks, bow and stern buoyancy tanks	826.15	m³
(All spaces that can be blown, without regulating, mine compensating and negative tanks)

Test and operating pressures.

Pressure hull and conning tower including periscope shafts with internal pressure equivalent to water pressure at the bottom of the pressure hull to	30 meters pressure head
Pressure-proof curved watertight bulkheads from the cupped side with internal pressure equivalent to water pressure at the bottom of the pressure hull to	30 meters pressure head
Watertight flat bulkheads with internal pressure equivalent to water pressure at the top of the pressure hull to	2 meters pressure head
Pressure-proof coning tower and hatch covers for assembly to	7.5 and 18 kg/cm² respectively
All hull shut off valves to construction specification	18 kg/cm²
The test for gas leaks (testing bulkhead tightness) has taken place per construction regulation SA 5 to 25 mm vacuum
Flood valves and emergency vent valves with internal pressure equivalent to water pressure at the top of main ballast tanks and main ballast and reserve fuel oil tanks to	8 meters pressure head
The body of the vent valves actuators are pressurized with water for strength to	25 kg/cm²

Page 8	A. Ship Information	U-Boat Type XB

8	I. General	U-boat Information

The body of the vent valves are pressurized with air for tightness to	12 kg/cm²
The valve for the vent ducts (main ballast and reserve fuel oil tanks) for strength and tightness to	18 kg/cm²
Vent valves with pressure equivalent to water pressure at the top of main ballast tanks or main ballast and reserve fuel oil tanks to	8 meters pressure head
Deck of the battery compartment by filling the battery compartment with air under pressure	100 mm Pressure head

High pressure air, oxygen and pressure oil flasks

28 high pressure compressed air flasks:	Operating pressure	205 kg/cm²
	Test pressure	280 kg/cm²
2 starting air flasks:	Operating pressure	75 kg/cm²
	Test pressure	120 kg/cm²
16 oxygen flasks:	Operating pressure	150 kg/cm²
	Test pressure	200 kg/cm²
4 pressure oil flasks:	Operating pressure	40-80 kg/cm²
	Test pressure	120 kg/cm²

Test and operating pressure (inner pressure)


Designation	From frame - frame	Tested with	Test pressure equivalent to water pressure at top of tank	Operating pressure kg/cm²

Stern buoyancy tank	A -16 - -9	air	2 meters
Main ballast tank 1	A - 9 - +8	water	8 meters
Main ballast and reserve fuel oil tank 2	A 8 - 24)	water
Main ballast and reserve fuel oil tank 3) port	A 24 - 34)
Main ballast and reserve fuel oil tank 8) stb.	A 99 - 109)
Main ballast and reserve fuel oil tank 9	A 109 - 128)
Fuel oil tank 1a port and stb.	A 34 - 43)	fuel oil	8 meters
Fuel oil tank 2a port and stb.	A 93 - 99)	fuel oil	8 meters

U-Boat Type XB	A. Ship Information	Page 9

U-boat Information	I. General	9


Designation	From frame - frame	Tested with	Test pressure equivalent to water pressure at top of tank	Operating pressure kg/cm²

Main ballast tank 4	A 43 - 53)	water	8 meters
Main ballast tank 5) port	A 53 - 63)
Main ballast tank 6) stb.	A 73 - 83)
Main ballast tank 7	A 83 - 93)
Main ballast tank 10	A 128 - 147	water	8 meters
Bow buoyancy tank	A 128 - 152	air	2 meters
Regulating and reserve fuel oil tank 1 port	D 41-1/2 - 45)	water	140 meters	16.5
Regulating and reserve fuel oil tank 1 stb.	D 41-1/2 - 45)
Regulating tank 2 port	D 45 - 48)
Regulating tank 2 stb.	D 45 - 48)
Negative buoyancy tank port	D 45-1/2 - 48)
Negative buoyancy tank stb.	D 45-1/2 - 48)
Mine compensating tank 1	A 63 - 66-1/3)	water	140 meters
Mine compensating tank 2	A 63 - 66-1/3)
Mine compensating tank 3	A 66-1/3 - 69-1/2)
Mine compensating tank 4	A 66-1/3 - 69-1/2)
Trim tank 1	D 7 - 11)	water	30 meters
Trim tank 2	D 7 - 11)
Trim tank 3	D 87 - 99)
Trim tank 4	D 87 - 99)
Torpedo compensating tank 1	D 11 - 13-1/2)	water	30 meters
Torpedo compensating tank 2	D 11 - 13-1/2)	water	30 meters
Water distillate tank 1)	D 18-1/2 - 21	water	0.5 meters
Water distillate tank 2)	D 18-1/2 - 21
Water distillate tank 3)	D 86 - 87
Fresh water tank 1	D 35-1/2 - 36-1/2)	water	4 meters
Fresh water tank 2	D 49 - 49-1/2)
Fresh water tank 3	D 58 - 61)
Fresh water tank 4	D 58 - 61)
Wash water tank 1	D 61 - 62)
Wash water tank 2	D 72 - 73)

Page 10	A. Ship Information	U-Boat Type XB

10	I. General	U-boat Information


Designation	From frame - frame	Tested with	Test pressure at top of tank	Operating pressure kg/cm²

Waste water tank 1	D 12-1/2 - 13-1/2)	water	1 meter
Waste water tank 2	D 33-1/2 - 35-1/2)
Waste water tank 3	D 58 - 58-1/2)
Waste water tank 4	D 70-1/2 - 72)
Fuel oil gravity feed tank	D 26 - 28	oil	6 meters
Pressure oil reservoir	D 47-1/2 - 49-1/2	oil	6 meters
Munitions magazine	D 49-1/2 - 55	water	filled to upper edge
Dirty lubricating oil tank	D 24 - 26	oil	6 meters
Lubricating oil collecting tank port	D 26 - 28	oil	6 meters
Lubricating oil collecting tank stb.	D 28 - 30	oil	6 meters
Lubricating oil supply tank 1	D 35-1/2 - 41	oil	6 meters
Lubricating oil supply tank 2	D 35-1/2 - 41	oil	6 meters
Lubricating oil supply tank 3	D 41 - 45-1/2	oil	6 meters
Lubricating oil supply tank 4	D 41 - 45-1/2	oil	6 meters
Mine compensating tank 5	D 74 - 77	water	8 meters
Mine compensating tank 6	D 74 - 77	water	8 meters
Mine compensating tank 7	D 77 - 80	water	8 meters
Mine compensating tank 8	D 77 - 80	water	8 meters
Fuel oil collecting tank	D 30 - 31	fuel oil	6 meters
Brine tank	D 14 - 15	water	0.5 meters

Materials.

Pressure hull, regulating and reserve fuel oil tanks, regulating tanks, external mine compensating tanks, negative tanks	S M ship construction steel St 52
Conning tower casing	Special material Wh - n/A
Conning tower deck	Chromium Nickel-Molybdenum-Steel
Flood valves	Steel casting
Flood valve frame	Steel casting
Vent valves, casing	Welded mild steel, with bronze
Vent valves, seat	Steel casting
Emergency vent valves	Steel casting
Intermediate valves (main ballast and reserve fuel oil tanks	Steel casting
Draining installation, piping	Steel 3529
Draining installation, equipment parts	Steel casting, seats bronze or red brass

U-Boat Type XB	A. Ship Information	Page 11

U-boat Information	I. General	11

Piping (in ballast tanks, fuel oil tanks, battery rooms, fresh water tanks )	Galvanized mild steel
HP compressed air flasks	Chromium Nickel-Molybdenum steel
HP compressed air piping	Copper
Oxygen flasks	Chromium Nickel-Molybdenum steel
Oxygen piping	Copper
Pressure oil flasks	Chromium Nickel-Molybdenum steel
Pressure oil piping	Steel tubing, copper plated interior
Equipment parts oxygen installation	Bronze
Ventilation ducts	Iron or aluminum
Pressure-proof equipment parts of the ventilation ducts	Bronze
Steam heat piping and heaters	Copper
Steam heat equipment parts	Bronze

All gear rods and linkages with their bearings installed outside the pressure hull are galvanized or made from sea water-proof material.

Weights. (see Secret document)

I.	Ship's hull including ballast	= %
II.	Auxiliary machinery for propulsion	= %
III.	Armor	= %
IV.	Propulsion plant including associated auxiliary machinery	= %
V.	Gunnery	= %
VI.	Torpedo weaponry	= %
VII.	Equipment	= %
VIII.	Fuel and lubricating oil	= %
IX.	Weight reserve	= %
Sum of I - IX = Construction displacement = 100%
Note: Above data is not filled because it is secret.

Stability.

The type XB U-Boat during

-cruise has form stability and during

-cruise it has weight stability. To achieve a sufficiently large

arm

Page 12	A. Ship Information	U-Boat Type XB

12	I. General	U-boat Information

		during -cruise and FG during -cruise, to increase stability, 50 kg weights are located in the ballast keel.
		General:
		The stability of the boat can be expressed as the large lever arm , called also "meta centric height", i.e. the distance between the center of gravity G and transverse meta center M (intersection of the upward force of buoyancy and ship vertical center-line).
		Heeling of the boat by the force P by angle creates the righting arm (stabilizing arm):

		The position of M over the buoyancy center F during -cruise depends on the position of the floating line (transverse water line gives the height of M).
		When heeling angles are small (0-2) the position of M can be considered as constant, so stabilizing arm * sin is also constant (starting stability).
		At large heeling angles the position of M is changing. In U-boats however, the stability at large declinations is not calculated - as you know, U-boats with sufficient starting stability are stable at large heeling angles. The "starting stability" will be called "stability".
		During -cruise M overlaps with buoyancy center F:

		The stabilizing arm * sin is equal for longitudinal and lateral declinations. Longitudinal stability during -cruise is also as large as transverse stability, whereof it reacts to trim changes.
		During -cruise the longitudinal stability is very large (MG approximately = ship length).

U-Boat Type XB	A. Ship Information	Page 13

U-boat Information	I. General	13



Location of transverse meta center (F), buoyancy center (M) and center of gravity (G)

		Note: Free surfaces are not accounted for in stability considerations.

		For the following trim conditions the corresponding approximate stability values ratio apply:
		a : b : c : d : e : f : g : h
		10 : 9.35 : 9.80 : 9.05 : 3.37 : 3.52 : 3.04 : 3.12

Page 14	A. Ship Information	U-Boat Type XB

14	I. General	U-boat Information

Condition A with mines

Condition A without mines

Condition B with mines

Condition B without mines

Condition A with mines

Condition A without mines

Condition B with mines

Condition B without mines

For the absolute values of the meta centric height

see secret documents.

The difference between the stability values for the boat with and without mines is not important and in practical operations in each case may be not taken into account.

Weapons overview (armament)

Boat armament:

bow mineshafts (each with 3 SMA-mines)

side mineshafts (each with 2 SMA-mines)

stern torpedo tubes

10.5 cm cannon (forward of the coning tower)

3.7 cm cannon (aft of the conning tower)

2 cm anti-aircraft gun )

on the conning tower

MG C/34 )

Machine guns

Mauser pistols

Side arms

Safety and rescue equipment overview.

Structural safety installations:

Spherical bulkheads for pressure-tight partition	4	Units
Watertight bulkheads	2	"
Half height watertight bulkheads	3	"
Hatch coamings	5	"
Air traps	5	"
Net cutter (removed)
Net deflector	3	"
Railing and tethers

U-Boat Type XB	A. Ship Information	Page 15

U-boat Information	I. General	15

Safety equipment:

High pressure air system, air volume at 205 kg/cm²	12,470	liters
Emergency blowing manifolds for all main ballast, main ballast and reserve fuel oil , and fuel oil tanks	2	units
Emergency air supply connection in the control room and in end rooms	5	units
Emergency vent valves for the main ballast tanks	10	units
Emergency vent valves for main ballast and reserve fuel oil tanks	8	units
Air purification system, sodium hydrate cartridges:	590	units
Oxygen renewal system, oxygen volume at 150 kg/cm²	800	liters
Battery ventilation with special battery ventilation fan
Compartment ready indicating system
Hull closure indicating system
Vent valve indicating system
Automatically switched on emergency lamps:	10	units
GHG installation
KDB installation
Nah S sonar installation
UT installation
Dry fire extinguishers ( CO₂ )	7	units
Flooding installation
Drainage installation
Damage control materials

Rescue equipment:

Rescue buoys with night signal light	2
Battery powered hand lamps	10
Life buoys	3
Emergency escape gear	72
Life jackets	55
Diving suit	1
Diving suit without weighting systems	1
Watertight suit for the emergency escape set	1
Life raft	2
Dinghy	1

For further information about safety and rescue equipment see section VIII.

Page 16	A. Ship Information	U-Boat Type XB

16	I. General	U-boat Information

Test data.

Speed

and


	Diesel engines			E motors

	Turns	Condition A	Condition B	Turns	Speed
	R.P.M.	knots	knots	R.P.M.	knots	knots

	Ahead

KF	170	7	6.0	70	2.1	1.8
LF	220	8.65	8.2	130	3.6	3.3
HF	270	10.5	10.0	180	4.8	4.6
2 x HF	320	12.25	11.7	220	6.0	5.7
GF	375	14.4	13.7	260	6.8	6.7
2 x GF	430	15.95	15.4
AK	470	17.2	16.4	300	7.6	7.5
3 x AK	485	17.65	16.8

	Astern

KFz	170			70
LFz	220			130
HFz	270			180
2 x HFz	340			240
AKz	400			290

Diving times.

1) While staying still seconds

2) At HF forward seconds

3) Fast diving seconds

4) Deepest allowable depth meters

U-Boat Type XB	A. Ship Information	Page 17

U-boat Information	I. General	17

	c)	Pressure dock trials.














	d)	Depth differences for bow and stern.
		See the chart on page 18.

Page 18	A. Ship Information	U-Boat Type XB

18	I. General	U-boat Information

Click the text to view an enlarged version of the chart turned 90 clockwise

Tauchungeunterschiede von Bug und Heck gegenüber der Druckmessertiefe
Diving differences for bow and stern as opposed to the depth meter

Achterlastig	Down by the stern
Bock für Netzabweiser	Support for net deflector
Bug	Bow
Bug (untere) Netzsäge	Bow (bottom of) Net saw/cutter
Bug höher	Bow higher
Bug tiefer	Bow deeper
Grad	Degrees
Heck	Stern
Höhertauchung	Shallower immersion
Kiel	Keel
Netzsäge (oben)	Net saw/cutter (top of)
Rudderhacke	Rudder heel (bottom of the rudder)
Tiefertauchung	Deeper immersion
Turm	Conning tower
Vorlastig	Down by the bow

U-Boat Type XB
A. Ship Information
Page 19

U-boat Information
I. General
19

6) Practical values.

a) Speeds for various operating conditions.

b) Behavior of the boat under different rudder angle and wind conditions.

Page 20	A. Ship Information	U-Boat Type XB

20	I. General	U-boat Information

Turning circle.

Turning circle diameter.

Depending on main rudder angle and speed.

Surfaced:


Trim Condition	Rudder angle	Turning circle diameter in meters
Trim Condition	Rudder angle	AK RPM=	GF RPM=	HF RPM=	LF RPM=	KF RPM=



A





B

Submerged:


Circle to	Rudder angle	Turning circle diameter in meters
Circle to	Rudder angle	AK RPM=	GF RPM=	HF RPM=	LF RPM=	KF RPM=



Stb.





Port

Note: RPM are valid at the moment of running into the turning circle and during the steady turning condition of the boat are accordingly lower.

U-Boat Type XB	A. Ship Information	Page 21

U-boat Information	I. General	21

Time to Reciprocal heading

Rudder Hard Over

and


Speed setting	Time to reciprocal heading
Speed setting	Trim Condition A	Trim Condition B	Submerged

AK
GF
HF
LF
KF

Time to put in and to take effect

with main rudders in astern cruise


Rudder angle	Time to put in		Time to result
Rudder angle	RPM=100	RPM=360	RPM=100	RPM=360

32°
30°
25°
20°
15°
10°

Main Rudder Limits

astern cruise


AKz	GFz	HFz	LFz	KFz

Page 22	A. Ship Information	U-Boat Type XB

22	I. General	U-boat Information

	d)	Behavior in a seaway.












	e)	Diving characteristics, crash dives.

U-Boat Type XB	A. Ship Information	Page 23

U-boat Information	I. General	23

	f)	Depth control characteristics normal.













		In a seaway

Page 24	A. Ship Information	U-Boat Type XB

24	I. General	U-boat Information

		During torpedo firing











		During mine deployment

U-Boat Type XB	A. Ship Information	Page 25

U-boat Information	I. General	25

	g)	Vibration:
		By engines at different RPM




		By torpedo firing




		By periscope with drag at speed
		Fixed eye-level periscope


		Attack periscope


		Control room periscope


		Rod antenna (extended)


		By mine deployment

Page 26	A. Ship Information	U-Boat Type XB

26	I. General	U-boat Information

		On this page (26 and the temporarily missing pages 27 and 28) sound levels will be added later, as soon as these are established for type XB submarines.

Note: Pages 27 and 28 are missing

U-Boat Type XB	A. Ship Information	Page 29

U-boat Information	II. Boat and Pressure hull	1

II.	Boat and pressure hull - including through-hull openings.
	1)	General construction of the boats.
		The Type XB U-boat is large, double-hull vessel. Between the pressure hull and the outer shell are located main ballast tanks, main ballast and reserve fuel oil tanks, fuel oil tanks, pressure-proof regulating tanks, mine compensating tanks and negative tanks. During submerged cruise, the main ballast tanks, main ballast and reserve fuel oil tanks and fuel oil tanks are connected with surrounding sea-water, so the outer shell need not be pressure-proof. In the free-flooding spaces over the pressure hull are located installations and equipment that do not need to be placed inside the pressure hull, such as the dinghy, inflatable boat, high pressure compressed air flasks, the mufflers and storage place for nautical equipment. The upper deck is designed to provide footing for handling and seamanship. It is also serves as the gun shooting platform. Above the upper deck is a pressure-proof conning tower, covered with a free-flooding casing. The bridge is located on the conning tower ceiling and is used as command station with armored casing during cruise. The command station during cruise is located inside the pressure-proof conning tower.
		The main engine installation consists of two 9-cylinder - 4 cycle diesel engines each of 2100 HP with charging manufactured by Fried. Krupp Germaniawerft for cruise and two E motors each of 550 HP manufactured by Fa. AEG for cruise.
		The boat's weaponry consists of 66 mines in 6 shafts of 3 each and 24 shafts of 2 each, also, a 10.5 cm gun, a 3.7 cm gun, a 2 cm anti-aircraft gun and a MG C 34.
		The torpedo armament consists of 2 aft tubes.
		The crew consists of:
		5 Officers
		5 Chief Petty Officers
		13 Petty Officers
		27 men
		Total crew: 50 men

Page 30	A. Ship Information	U-Boat Type XB

2	II. Boat and Pressure hull	U-boat Information

	2)	Construction of the pressure hull.
		The pressure hull is formed as cylindrical tube, which tapers towards both ends and is capped by two outside cambered dished plates. The hull encloses all installations which are not pressure-proof or water-tight. The pressure-proof conning tower is located at half of the pressure hull length. It is accessible from outside by the conning tower hatch and from the pressure hull by the control room hatch. The pressure hull is divided into 5 compartments by 4 pressure-proof spherical bulkheads and subdivided into 7 rooms by two watertight bulkheads.
		The pressure hull is constructed from 17 mm and 20.5 mm thick rolled steel plates and is stiffened by means of 88 inner frames which are made from bulb tee girders.
		The distance from one frame to another is almost 800 mm. The distance of individual frames varies slightly. Particularly stressed areas (i.e. under the conning tower and around the torpedo hatch, exhaust valves and diesel engine room patch) are further strengthened with thicker plates and transverse frames. The forward end of pressure hull is capped by an outside cambered dished plate of cast steel, with no openings for torpedo tubes. The aft end is capped by an outside cambered dished plate with openings for torpedo tubes 1 and 2. The thickness of plating in the cylindrical part of the hull is 20.5 mm, in the end parts is 17 mm, the thickness of plating at aft hull ending is 30 mm, and at the forward hull ending is 22 mm.

	3)	Partitioning of the pressure hull.
		Compartment I Room 1: Aft torpedo room (Frame D 0 - 13-1/2).
		The access to this room is through torpedo loading hatch, aft torpedo room hatch (over the aft WC to starboard) and through the hatch in the curved bulkhead (frame 13-1/2).

U-Boat Type XB	A. Ship Information	Page 31

U-boat Information	II. Boat and Pressure hull	3

The room is used as quarters for 8 men. Located there are: torpedo tubes 1 and 2 with the associated auxiliary equipment, driving motors for the main rudder and diving planes, main rudder emergency steering station, auxiliary drain pump 1, 5 oxygen flasks.

Trim tank 1 and 2, torpedo compensating tank 1 and 2, waste water tank 1, aft WC, high and low pressure air distributors, emergency blowing manifold, compressed air pistons for operating vent valves, vent valves for main ballast tank 1 and main ballast and reserve fuel oil tanks 2 and 3, charging switchboard for electric torpedoes, auxiliary switchboard 1 (110 V).

Compartment II E motor, diesel engine, galley and petty officers room (battery room 1) (Frame D 13-1/2 - 45-1/2).

Room 2: E motor room (Frame D 13-1/2 - 22).

Access to this room is through the hatch in the curved bulkhead 13-1/2 and through the hatch in the watertight bulkhead (aft) of the diesel engine room.

In this room are located: E motors starboard and port with two fan blowers, main switchboards starboard and port, auxiliary switchboard 2 and 2a (220 V), compressed air operated main clutches starboard and port, main thrust bearings starboard and port, electric air compressors 1 and 2, distilling units 1 and 2, 1 brine tank, 2 water distillate tanks and cooling water pump. Also the gyro-compass, radio receivers and transmitters rotary converters, as well as 1.4 kVA and 6 kVA converters. Also the converters for gyro angle setting gear, fire control and UT installation.

Room 3: Diesel engine room (Frame D 22 - 35-1/2).

Access to this room from aft is through the hatch in the watertight bulkhead (Frame D 22) from the E motor room and from forward through the hatch in the galley watertight bulkhead (Frame D 35-1/2). In this room are located: diesel engines starboard and port with associated auxiliary machinery, compressed air operated diesel engine clutches starboard and port, 2 auxiliary lubricating oil pumps, 1 auxiliary cooling water pump, starboard and port lubricating oil cooler, 1 intake and 1 exhaust air fan, air conditioning unit, diesel air compressor 3 and 4, 1 hand lubricating oil pump, 1 hand cooling water pump, 1 fuel oil supply pump, 1 hand dirty oil pump, 1 dirty oil tank, lubricating oil purifying system, lubricating oil collecting tanks starboard and port, fuel oil collecting tank, 1 lubricating oil and 1 fuel oil-

Page 32	A. Ship Information	U-Boat Type XB

4	II. Boat and Pressure hull	U-boat Information

		gravity tanks, waste water tank 2, compressed air pistons for operating vent valves vent valves for main ballast tanks 4 and 5, the inboard exhaust valves with operating gear, 2 diesel engine air induction trunk foot valves starboard and port, 1 ventilation intake foot valve, 1 ventilation exhaust foot valve, 8 mine release arrangements for mine shafts 51/53 - 64/66.
		Room 4: Galley (Frame D 35-1/2 - 38).
		Access to this room from the upper deck is through the galley hatch, from the diesel engine room through the hatch in the forward watertight diesel engine room bulkhead, from forward from the Petty Officers room. In this room are located: battery automatic circuit breaker 1 to starboard, refrigerator plant with small provision locker, wash and dryer room, 1 stove, 2 mine release arrangements for mine shafts 50/48 - 49/47.
		Room 4: Petty Officers room (Frame D 38 - 45-1/2).
		The access is through the galley and the hatch in the curved bulkhead 55-1/2. In this room are located: battery room 1 with battery 1, fresh water tank 1, lubricating oil supply tanks 1, 2, 3 and 4. It is used as quarters for 12 petty officers. 2 mine release arrangements for mine shafts 46/44 and 45/43.

		Compartment III
		Room 5: Control room (Frame D 45-1/2 - 55-1/2).
		The access is through the hatches in curved bulkheads at frame 45-1/2 and 55-1/2 and through the control room hatch. In the control room are located: main drain pump, auxiliary drain and trim pump, drive for control room periscope, auxiliary switchboard 3, 4 pressurized hydraulic oil flasks, blowing distributor for main ballast tanks and main ballast and reserve fuel oil tanks, regulating tanks, fuel oil tanks and so on, 2 hydraulic oil pumps, 1 battery ventilation fan, 5 oxygen flasks, diving planes control station, gyro-compass, 1 main rudder control station, 1 emergency main rudder control station, radio direction finder, rod antenna, TDC, depth sounding equipment, compressed air pistons for operating vent valves, vent valves for main ballast tanks 6 and 7, munitions magazine, log installation, 2 engine order telegraphs, 6 mine release arrangements for mine shafts 42/40 - 33/31, and trim controller.

U-Boat Type XB	A. Ship Information	Page 33

U-boat Information	II. Boat and Pressure hull	5

		Compartment IV Room 6: Officers room, Chief Petty Officers room and 2 rooms for crew one above the other (Frame D 55-1/2 - 70-1/2).
		The access is through the hatches in the curve bulkheads at frame 50-1/2 and 70-1/2 and through the officers' room hatch. The officers' room, chief petty officers room and 2 rooms for crew are separated by 3 wooden bulkheads. In this room are located: battery automatic circuit breaker 2, captain, officers, chief petty officers quarters, rooms for men one above the other, listening room, radio room, provision locker, fresh water tanks 3 and 4, waste water tank 3, wash water tank 1, 6 mine release arrangements for mine shafts 30/28 - 21/19, compressed air pistons for operating vent valves, vent valves for main ballast and reserve fuel oil tanks 8 and 9.

		Compartment V Room 7: Forward mine room (Frame D 70-1/2 - 89).
		Access is through the hatch in the curved bulkhead at frame 70-1/2 and through forward mine room hatch. In this room are located: auxiliary drain pump 2, 6 forward mine shafts (16/18 - 1/3) with mine release arrangements and release controller, mine compensating tanks 5, 6, 7, 8, trim tanks 3 and 4, waste water tank 4, wash water tank 2, forward WC, lathe and drill stand, 5 bunks for men, forward capstan driving motor, compressed air pistons for operating vent valves, vent valves for main ballast tank 10, a second refrigerator plant (until the installation of deep-freezer equipment), potato storage and driving motor for Voith-Schneider-Propeller (only on U-118).
		Conning tower (Frame D 48 - 53)
		Access through the control room and conning tower hatches. In this room are located: forward and aft conning tower periscopes with their driving motors, 1 main rudder control station, 1 torpedo fire control station, 2 engine order telegraphs, main rudder angle indicator, diving planes angle indicators, log repeater, gyro-compass repeater.

	4)	Conning tower structure.
		The conning tower is used as command station during cruise.
		The conning tower in horizontal cross-section is an ellipse in the aft section and the arc of a circle in the lateral and forward sections. The radius of the forward arc is 700 mm, and that of the side arcs 2500 mm. The conning tower is topped with a cast steel plate with openings for the conning tower hatch and conning tower periscopes. Clear width of the conning tower is 2080 mm, clear

Page 34	A. Ship Information	U-Boat Type XB

6	II. Boat and Pressure hull	U-boat Information

		length is 3460 mm. The conning tower is also enclosed by the casing, which reduces drag during cruise.
		In the conning tower casing are located: cooling water head tank, 2 pressure-proof containers for 3.7 cm ready-use ammunition, 2 diesel engine air induction trunks, 1 ventilation intake and 1 ventilation exhaust air ducts and 1 upper deck WC.

	5)	Openings in the pressure hull.
		The most important openings are:

		Aft torpedo room (Frame D 0 - 13-1/2)
		Aft torpedo room hatch, torpedo loading hatch, torpedo tubes 1 and 2, 1 hull valve from sea for flooding torpedo compensating tanks 1 and 2, 1 hull valve for auxiliary drain pump 1 discharge, 2 openings for the aft WC, 1 opening for main rudder, 1 opening for aft diving planes.

		E motor room (Frame D 13-1/2 - 22)
		2 openings for propeller shafts starboard and port, 1 hull valve for cooling water pump intake and air compressor cooling line, 1 hull valve for cooling water, air cooler and air compressor cooling line discharge, E motor assembly patch.

		Diesel engine room (Frame D 22 - 35-1/2)
		Diesel engine assembly patch, 2 openings for exhaust gas valves, 2 hull valves for cooling water lines for cooling internal exhaust gas valves, 2 diesel engine air induction trunk foot valves, 1 ventilation intake foot valve, 1 ventilation exhaust foot valve, 2 hull valves for cooling water intake

		Galley (Frame D 35-1/2 - 38)
		Galley hatch

		Petty officers room (Frame D 38 - 45-1/2)
		Assembly patch for battery 1

U-Boat Type XB	A. Ship Information	Page 35

U-boat Information	II. Boat and Pressure hull	7

		Control room (Frame D 45-1/2 - 55-1/2)
		Control room hatch, radio direction finder, control room periscope, rod antenna, connection of the battery exhaust trunk to the ventilation exhaust duct, 1 hull valve main drain pump intake and for flooding the regulating tanks.

		Conning tower (Frame D 48 - 53)
		Conning tower forward and aft periscopes, conning tower hatch and voice tube.

		Officers room (Frame D 50-1/2 - 70-1/2)
		2 openings for the antenna trunks, officers room hatch, assembly patch for the battery 2.

		Forward mine room (Frame D 70-1/2 - 89)
		Forward mine room hatch, 1 hull valve for auxiliary drain pump 2 discharge and for flooding the mine compensating tanks 5-8, 1 opening for forward diving planes and 1 opening for the rotating passive hydrophone (KDB)

	6)	Construction of the outer shell.
		The outer shell consists of an outer hull, which encloses the pressure hull and the upper deck, located above the pressure and the outer hull. The outer hull determines the form of the boat in the water and hence the drag during cruise. The outer hull in the type XB boats is divided into main ballast tanks, main ballast and reserve fuel oil tanks, fuel oil tanks, regulating and reserve fuel oil tanks, regulating tanks, mine compensating tanks, negative tanks, bow and stern buoyancy tanks and exhaust gas spark arrestors. The space between the outer hull and upper deck is used to locate various ship and machinery installations as well as for storage of nautical equipment and ready-use ammunition.
		The distance between the outer shell frames is typically 500 mm, but there is some variation resulting from the boat's construction.
		The upper deck stretches over the entire boat and is fitted to the vessel's form.
		Between frames A 20 - A 90 the upper deck is horizontal, in the forward part it rises and in the aft part it falls.
		Between frames A 2 - A 128 the upper deck is covered with wood, while at the forward and aft end parts it is constructed of steel plates.
		The distance between the upper deck frames is equal to the distance between the outer shell frames located below.

Page 36	A. Ship Information	U-Boat Type XB

8	II. Boat and Pressure hull	U-boat Information

The conning tower is covered with steel plate casing. It encloses four air ducts, antenna trunk, radio direction finder, the rod antenna, control room periscope, 3.7 cm ready-use ammunition in pressure-proof containers, upper deck WC and the cooling water head tank. Over the conning tower there is a bridge, which is used as command station during

cruise and as the battle station for the 2 cm anti-aircraft gun. Two extended diesel engine air induction trunks are installed in the bridge steel plate fairing on both sides.

Special stiffeners:

The parts of the torpedo tubes extending beyond the pressure hull are supported by torpedo tube bulkheads located in stern part of the outer shell.

Places especially exposed to loads (area of dive planes, the widest part of the hull, lateral mine shafts, propeller shaft supports, anchor capstan etc.) are braced with stringers, girders and beams.

7).

Partitioning of the outer shell.

The outer shell is divided by means of watertight, oil tight and pressure-proof bulkheads into following tanks:
Stern buoyancy tank	Frame	-16 - -9
Main ballast tank 1	"	-9 - +8
Main ballast and reserve fuel oil tank 2 stb. and 2 port	"	8 - 24
Main ballast and reserve fuel oil tank 3 stb. and 3 port	"	24 - 34
Fuel oil tank 1a stb. and 1a port	"	34 - 43
Main ballast tank 4 stb. and 4 port.	"	43 - 53
Main ballast tank 5 stb. and 5 port	"	53 - 63
Regulating and reserve fuel oil tank 1 stb. and 1 port	"	63 - 68-1/2
Regulating tank 2 stb. and 2 port	"	68-1/2 - 73
Mine compensating tank 1 and 2 )	"	63 - 66-1/3
Mine compensating tank 3 and 4 ) lying underneath the regulating tanks	"	66-1/3 - 69-1/2
Negative buoyancy tank)	"	69-1/3 - 73
Main ballast tank 6 stb. and 6 port	"	73 - 83
Main ballast tank 7 stb. and 7 port	"	83 - 93
Fuel oil tank 2a stb. and 2a port	"	93 - 99
Main ballast and reserve fuel oil tank 8 stb. and 8 port		99 - 109

U-Boat Type XB	A. Ship Information	Page 37

U-boat Information	II. Boat and Pressure hull	9

Main ballast and reserve fuel oil tank 8 stb. and 8 port	"	109 - 128
Main ballast tank 10	"	128 - 147
Bow buoyancy tank (over main ballast tank 10)	"	128 - 152

Page 38	A. Ship Information	U-Boat Type XB

1	III. Diving Installations	U-boat Information

III.	Diving Installations.
1)	Tanks and fuel oil tanks.
	a)	Main ballast tanks.
		During surfaced cruise the boat floats by means of 6 main ballast tanks. Main ballast tanks 1 and 10 are located in the bow and stern parts of the outer shell and have flooding slits. The pairs of starboard and port main ballast tanks 4 and 5 are located in the outer shell behind the regulating tanks, the pairs of starboard and port main ballast tanks 6 and 7 are located forward of the regulating tanks. Each main ballast tank is flooded by means of 4 flooding valves, each pair is operated by means of linkage rods from the inside of the boat. The lateral mine shafts are located within main ballast tanks 4, 5, 6, 7 starboard and port.

	b)	Main ballast and reserve fuel oil tanks.
		Four pairs of main ballast and reserve fuel oil tanks 2, 3, 8 and 9 (starboard and port) are provided located in the outer shell, of those each individual tank can be flooded by means of 4 flood valves just as for the main ballast tanks. Each pair of adjacent flood valves is operated by means of a linkage rod from inside the boat. Main ballast and reserve fuel oil tanks 2 and 3 are located in the outer shell between main ballast tank 1 and fuel oil tank 1a, main ballast and reserve fuel oil tanks 8 and 9 are located between the fuel oil tank 2a and main ballast tank 10.

	c)	Bow and stern buoyancy tanks.
		The aft and forward parts of the outer shell are constructed as stern and bow buoyancy tanks and are used to dampen longitudinal pitching of the boat. Both tanks have flood slits and are vented by means of one vent valve each operated from the inside of the boat. Stern and bow buoyancy tanks can be blown with compressed air.

U-Boat Type XB	A. Ship Information	Page 39

U-boat Information	III. Diving Installations	2

Location and capacity of main ballast tanks, main ballast and reserve fuel oil tanks, stern buoyancy tank and bow buoyancy tank.


Main Ballast tanks (and reserve fuel oil tanks)	Location		Net capacity

Stern buoyancy tank	Frame	-16 - -9	8.40 m³
Main ballast tank 1	Frame	-9 - +8	44.30 m³
Main ballast and reserve fuel oil tank 2	Frame	+8 - 24	43.25 m³
Main ballast and reserve fuel oil tank 3 x)	Frame	24 - 34	58.20 m³
Main ballast tank 4	Frame	43 - 53	78.30 m³
Main ballast tank 5	Frame	53 - 63	88.95 m³
Main ballast tank 6	Frame	73 - 83	88.20 m³
Main ballast tank 7	Frame	83 - 93	75.75 m³
Main ballast and reserve fuel oil tank 8 x)	Frame	99 - 109	69.05 m³
Main ballast and reserve fuel oil tank 9	Frame	109 - 128	67.55 m³
Main ballast tank 10	Frame	128 - 147	39.00 m³
Bow buoyancy tank	Frame	128 - 152	28.00 m³

x) Applies only with opened flood valves

Regulating tanks and regulating and reserve fuel oil tanks.

To compensate for changes of weight caused by different load conditions and differences in water density, 2 regulating and reserve fuel oil tanks and 2 regulating tanks are provided. They are located in the outer shell and are constructed as pressure-proof.

Location and capacity of regulating tanks:


Designation	Location	Net capacity

Regulating and reserve fuel oil tank 1 port	D 41-1/2 - 45	16.85 m³
Regulating and reserve fuel oil tank 1 starboard	D 41-1/2 - 45	16.85 m³
Regulating tank 2 port	D 45 - 48	13.30 m³
Regulating tank 2 stb.	D 45 - 48	13.30 m³

Page 40	A. Ship Information	U-Boat Type XB

4	III. Diving Installations	U-boat Information

The 2 regulating and reserve fuel oil tanks and regulating tanks can be flooded from sea and emptied by means of compressed air or by means of main drain or auxiliary drain and trim pump. The tanks are tested under a pressure of 14 kg/cm², and should be blown with a maximum pressure difference between the external pressure and blowing air equal to 16 kg/cm² (see paragraph I 2 d).

As a protection against too rapid increase in the pressure in the regulating and reserve fuel oil tanks and in regulating tanks while blowing (when the tanks are filled with water), the vent lines are lengthened, so when the tanks are flooded, an air cushion of 6% of tank capacity is created.

Trim tanks.

To keep the boat balance during submerged cruise two trim tanks in aft torpedo room and two trim tanks in forward mine room are installed. They are connected with two trim lines by means of two trim controllers. In each of the two trim lines a trim valve and a water meter is installed. Trimming takes place by means of compressed air or the auxiliary drain and trim pump.

All 4 trim tanks are tested at a pressure of 3 kg/cm² and are located 6.97 meters apart.

Position and capacity of trim tanks:

Aft - 27.25

Forward + 34.45


Designation	Location	Net capacity

Trim tank 1	D 7 - 11	3.940 m³
Trim tank 2	D 7 - 11	3.940 m³
Trim tank 3	D 87 - 89	3.778 m³
Trim tank 4	D 87 - 89	3.778 m³

U-Boat Type XB	A. Ship Information	Page 41

U-boat Information	III. Diving Installations	5

Negative buoyancy tanks.

The pressure proof negative tanks starboard and port located in the outer shell under regulating tank 2 and are used to gain negative buoyancy during crash diving. The capacity of each tank is 7.85 meters³. The tanks are flooded through the flooding valves and are also blown through the same valves by means of compressed air. The tanks are vented to the inside of the boat. The flooding valves are operated form the control room. The negative tanks are located between frames 45 ½ - 48.

Torpedo compensating tanks.

Torpedo compensating tanks 1 and 2 are located in the aft torpedo room and are flooded through the water flow meter. Each tank has a sounding line and is connected to the drain line.


Designation	Location	Net capacity	Test pressure

Torpedo compensating tank 1	D 11 - 13-1/2	3.24 meters³	3 kg/cm²
Torpedo compensating tank 2	D 11 - 13-1/2	3.92 meters³	3 kg/cm²

Mine compensating tanks.

8 mine compensating tanks are used to equalize the weight during mine launching. Tanks 1 - 4 are located outside the pressure hull, under the regulating and reserve fuel oil tanks and are pressure proof. Tanks 4 - 8 are located inside the pressure hull, in the forward mine room, at its sides and are pressure proof up to a pressure of 4 kg/cm². All tanks are connected to the drain and flooding line and can be drained by means of drain pumps. Pressure proof tanks 1 - 4 can be also drained by means of compressed air.

Page 42	A. Ship Information	U-Boat Type XB

4	III. Diving Installations	U-boat Information


Designation	Location		Net capacity	Test pressure

Mine compensating tank 1	D)	41-1/2 - 43-1/2	7.55³)	14 kg/cm²
Mine compensating tank 2	D)	41-1/2 - 43-1/2	7.55³)
Mine compensating tank 3	D)	43-1/2 - 45-1/2	7.55³)
Mine compensating tank 4	D)	43-1/2 - 45-1/2	7.55³)
Mine compensating tank 5	D)	74 - 77	3.65³)	4 kg/cm²
Mine compensating tank 6	D)	74 - 77	3.65³)
Mine compensating tank 7	D)	77 - 80	2.25³)
Mine compensating tank 8	D)	77 - 80	2.25³)

Blowing and exhaust gas blowing installation.

Compressed air blowing.

The main ballast tanks and main ballast and reserve fuel oil tanks are blown with compressed air up to 30 kg/cm², fed from the blowing distributor, which is located on the starboard side of the control room. The ballast tanks are gathered and grouped into 3 groups, which are fed through the common main blowing valve from the high pressure air distributor or through the auxiliary blowing valve from high pressure compressed air bank 7.

Group 1 = Main ballast tank 1, Main ballast and reserve fuel oil tank 2 and Main ballast and reserve fuel oil tank 3

Group 2 = Main ballast tank 4 starboard., Main ballast tank 4 port, Main ballast tank 5 starboard, Main ballast tank 5 port, Main ballast tank 6 starboard, Main ballast tank 6 port, Main ballast tank 7 starboard, Main ballast tank 7 port.

Group 3 = Main ballast and reserve fuel oil tank 8, Main ballast and reserve fuel oil tank 9 and Main ballast tank 10

The dedicated blowing distributor is used to blow the bow and stern buoyancy tanks and both fuel oil tanks 1a and 2a (starboard and port).

(for the compressed air and emergency blowing manifold see Safety and Rescue Installations).

Exhaust gas blowing.

Exhaust gas from the diesel engines is used to blow residual water from the ballast tanks. Exhaust gases are fed through the main blowing valves port and starboard to the exhaust gas blowing manifold. The manifold is located outside the pressure hull, over the control room, on the starboard side. From the manifold the gases go through 10 valves - operated from the control room by means of linkage rods passing through the hull - to the main ballast tanks and main ballast and reserve fuel oil tanks. Exhaust gas pressure should be 0.7 at.

U-Boat Type XB	A. Ship Information	Page 43

U-boat Information	III. Diving Installations	6

Venting and vent valves.

Vent valves of the main ballast tanks and main ballast and reserve fuel oil tanks are operated by means of compressed air (or by hand) and are gathered into 6 groups:

Compressed air control valve 1 (aft)	Group 1	-	Main ballast tank 1
Compressed air control valve 1 (aft)	Group 2	-	Main ballast and reserve fuel oil tank 2, Main ballast and reserve fuel oil tank 3
Compressed air control valve 2 (amidships)	Group 3	-	Main ballast tank 4, Main ballast tank 5
Compressed air control valve 2 (amidships)	Group 4	-	Main ballast tank 6, Main ballast tank 7
Compressed air control valve 3 (forward)	Group 5	-	Main ballast and reserve fuel oil tank 8, Main ballast and reserve fuel oil tank 9
Compressed air control valve 3 (forward)	Group 6	-	Main ballast tank 10

Each main ballast tank and main ballast and reserve fuel oil tank (except main ballast tank 1) is provided with a vent trunk on the starboard and port side. Each trunk can be shut off by means of its own emergency vent valve. The emergency vent valves are operated from inside the pressure hull. Gate valves are installed in the vent trunks of the main ballast and reserve fuel oil tanks (starboard and port), which should be closed when tanks are used as reserve fuel oil tanks. These trunks are pressure proof between the gate valves and emergency vent valves. The vent valve of main ballast tank 1 is located in the top cover of the tank, at the height of the upper deck. No emergency vent valve is provided for this tank. Two separate vent trunks are combined at the vent valve chamber for main ballast tank 10, which begin at the aft part, at the starboard and port side of the tank, and which are provided with emergency vent valves at the tank top cover. The pairs of main ballast tanks (starboard and port) 4 and 5, 6 and 7 and the pairs of main ballast and reserve fuel oil tanks (starboard and port) 2 and 3, 8 and 9 combine their 4 vent trunks in 2 vent valve chambers, with 2 coupled vent valves located side by side. And so, for example main ballast and reserve fuel oil tanks 2 and 3 starboard are vented through main ballast and reserve fuel oil tanks 2 and 3 starboard vent valve, while the main ballast and reserve fuel oil tanks 2 and 3 port are vented through the main ballast and reserve fuel oil tanks 2 and 3 port vent valve. Both vent valves are connected by means of a transverse beam, which in turn is operated from the inside of the boat by means of a vertical linkage rod.

(see the drawing)

Page 44	A. Ship Information	U-Boat Type XB

7	III. Diving Installations	U-boat Information

Anordung der Entlüftungsleitungen - Layout of the Vent trunks

druckfest ausgefürt Pressure-proof construction

Entlüftungsanschluß Gate valve

Entlüftungsventil Vent valve

hinten Aft

Notverschlußklappe Emergency vent (flap) valve

Tauchz. Main ballast tank

Traverse Cross-connection

Treibölb. Fuel oil tank

vorn Forward

U-Boat Type XB
A. Ship Information
Page 45

U-boat Information
III. Diving Installations
8

4) Compressed air systems.

a) Air compressor.

Compressed air, which is used for blowing the main ballast tanks, main ballast and reserve fuel oil tanks, regulating and reserve fuel oil tanks, regulating tanks, starting diesel engines, for the torpedo launching installation, anchor installation and other systems, is produced by 2 electric air compressors located in E motor room and by 2 diesel air compressors located in diesel engine room.

Compressed air is under maximum pressure of 205 kg/cm².

(for details see section B II 1 c)

b) High pressure compressed air flasks.

Compressed air is stored in 28 compressed air flasks with total capacity of 12.47 meters³. The flasks - tested with pressure 255 kg/cm² - are gathered into 8 groups:

Group and number of flasks

Location

Capacity of the Group

Capacity of each flask

1 (2)
In Aft torpedo room
900 liters

445 liters

2 (4)
Upper deck above the E-motor room
1780 liters

445 liters

3 (4)
Upper deck above the Diesel engine room
1780 liters

445 liters

4 (2)
In Wardroom over the forward battery
890 liters

445 liters

5 (4)
Upper deck over the Wardroom
1780 liters

445 liters

6 (4)
Upper deck over the Forward mine room
1780 liters

445 liters

7 (4)
In Forward mine room
1780 liters

445 liters

8 (4)
Upper deck over the Forward mine room
1780 liters

445 liters

Therefore there are 3570 meters³ of compressed air in the pressure hull (groups 1, 4, 7) and 8900 meters³ of compressed air outside the pressure hull, under the upper deck (groups 2, 3, 5, 6, 8).

Page 46	A. Ship Information	U-Boat Type XB

9	III. Diving Installations	U-boat Information

Compressed air equipment.

The 8 compressed air flask groups are connected by lines to the group distributor, located on the port side of the control room. From this distributor the air is led to the high pressure air distributors in the control room and in the aft torpedo room, to the blowing distributor and to the other distributors. In the aft torpedo room and in the forward mine room there are also emergency blowing manifolds.

From the high pressure air distributor in the control room lines go to separate medium and low pressure air distributors.

Available medium-pressure air distributors:

1)	3 Main ballast tanks and or main ballast and reserve fuel oil blowing distributors with a common main blow valve
2)	1 blowing air distributor for regulating tanks
3)	1 blowing air distributor for mine compensating tanks 1-4
4)	1 regulating valve for negative tanks
5)	1 blowing air distributor for watertight bow and stern, fuel oil tank 1a and 2a
6)	1 emergency blowing manifold in the aft torpedo room and 1 in the forward mine room

Available low pressure distributors:

1)	Low-pressure distributor in the control room to starboard (air entry via 2 regulating valves)
2)	Pressure reducing valve and air pressure regulating valve for stern capstan motor (205 at > 4 at)
3)	Pressure reducing valve and air pressure regulating valve for anchor capstan motor (205 at > 4 at)

The following use compressed air:

1)	High-pressure equipment
	a)	Torpedo test installation in the aft torpedo room
	b)	Hydraulic oil system in the control room
2)	Medium-pressure equipment
	a)	Blowing all main ballast tanks, main ballast and reserve fuel oil tanks, watertight bow and stern, fuel oil tanks
	b)	Blowing regulating and reserve fuel oil tanks and regulating tanks (safety valve 10 at)
	c)	Blowing negative tanks
	d)	Starting air flasks in the diesel engine room
	e)	Blowing mine compensating tanks 1-4

In case of damage the control room, the main ballast tanks and main ballast and reserve fuel oil tanks can be blown by means of separate emergency blowing manifolds.

U-Boat Type XB	A. Ship Information	Page 47

U-boat Information	III. Diving Installations	10

3)	Low-pressure equipment (branched direct from the low-pressure air distributor)
	a)	Torpedo launching installation in aft torpedo room, blowing torpedo compensating tank 1 and 2
		Aft head, forward head, air driven tool connection in aft torpedo room
	b)	Blowing out the cooling water hull valve in the E-motor room
		Main clutch air pressure valve
		Blowing out the 3 cooling water hull valves in the diesel engine room
		Tool connection in the diesel engine room
		Grinding mechanism for the exhaust valves
		Blowing out the heater lines of the steam generator system starboard and port
	c)	Forward diving plane clutch
		Aft diving plane clutch
	d)	Main ballast tanks and main ballast and reserve fuel oil vent valve operating gears
	e)	Marcks raft/buoy above the petty officers room
		Marcks raft/buoy above the ward room
	f)	Rod antenna raising gear
		Direction finding loop raising gear
		2 tyfone air whistles on the conning tower
		Antenna shaft
		Tool connection in the control room
		Trim system
		Blowing out the hull valve to sea

Pumps.

Regulating and reserve fuel oil tanks, regulating tanks and pressure-proof mine compensating tanks 1 - 4 can be blown by means of compressed air, but the regulating tanks and all mine compensating tanks (1 - 8) can also be drained by means of the main drain pump, both auxiliary drain pumps as well as by the auxiliary drain and trim pump.

Diving planes.

The boat is provided with a forward and aft pair of diving planes. The planes are driven by means of a hydraulic oil motor, powered from the hydraulic oil system in the control room. In case of failure of the hydraulic drive, the planes can switched from the control room by means of low pressure compressed air driven clutches to manual operating mode. Switching back to the hydraulic drive is done manually in the forward mine room or aft torpedo room respectively.

(For performance data see section B II 1 a)

Page 48	A. Ship Information	U-Boat Type XB

1	IV. Armament	U-boat Information

IV.	Armament.
1)	Mine installations.
	The boat can carry 66 SMA mines in 30 vertical, rounded shafts. 6 pressure-proof shafts are located one after another in the forward mine room, welded to the pressure hull, each holding 3 mines. The 6 shafts extend from the bottom edge of the keel up to about 50 cm over the upper deck. The upper parts of the shafts rising above the deck are covered by a common, streamlined casing.
	6 mine shafts are installed on each side of the boat, in the main ballast tanks (4, 5, 6, 7) starboard and port. Each shaft can carry two mines. The shafts extend from the bottom up to the top edge of the outer shell, which at this location is almost rectangular in the transverse section. All mine shafts are open at the bottom, while at the top end they are closed by a hinged, perforated cover. Laterally, on the outer side of the mine shafts, at the height of the anchor of each loaded mine, there are openings for the mine releasing and mine holding gear. The gear consists of horizontal locking plates, rotated by vertical shafts. The shafts are rotated hydraulically by means of a bevel wheeled gear from the inside of the boat. The parts of the locking plates which protrude inside the mine shaft lock the mines with their locking cleats. When the locking plate is rotated in such way, that it no longer protrudes inside the mine shaft, the mine falls out of the shaft or the mines can be loaded to the shaft from above. The locking plates in each mine shaft are so located, that the loading and launching of the mines is to be done in fixed sequence. In case of damage to the hydraulic oil drive for the releasing gear, it can be driven manually by means of a handle and auxiliary gear.
	The SMA mines weigh 1575 kg, displace 1100 liters of water, so have 475 kg of negative buoyancy.

U-Boat Type XB	A. Ship Information	Page 49

U-boat Information	IV. Armament	2

2)	Torpedo installations.
	a)	Torpedo tubes.
		The boat is provided with 2 underwater, standard caliber torpedo tubes. These are located side by side in the aft torpedo room and are supported by the aft end cap of the pressure hull and the torpedo bulkhead. Streamlined shutters are connected to the outer doors. When the horizontally pivoting torpedo tube outer doors are opened, the shutters are pushed up, into the outer shell. The tube end located inside the pressure hull is closed by the breech door with a locking ring. The interlock mechanism between the breech and outer door operating gears prevents simultaneous opening.

	b)	Stowage.
		Apart from torpedoes loaded into torpedo tubes I and II, there can be also 5 reserve torpedoes stored inside the pressure hull. Three of them are stored under the floor plates of the aft torpedo room, on the torpedo compensating tanks and trim tanks.
		2 more torpedoes can be stored on the floor plates in the same room.
		8 pressure-proof, upper deck containers installed outside the pressure hull, on both sides at the top covers of saddle tanks. These containers are made of aluminum and can store one torpedo each.
		These torpedoes are designated for transfer to other boats.

	c)	Torpedo loading equipment.
		The torpedo loading equipment is the same for the G7a or G7e torpedo. A portable crane, which is stored under the upper deck, can be mounted on the starboard or port side of the upper deck, just in front of the torpedo loading hatch and is used for loading from sea or other vessels.

Page 50	A. Ship Information	U-Boat Type XB

3	IV. Armament	U-boat Information

		The portable crane is mounted in pivot bearings installed at the upper deck. The torpedoes are slid down into the inside of the boat by means of a chute and boom with winch and corresponding support beams which assure proper motion of the torpedo.
		Transport splints with gear racks are installed in the boat. Each splint is hung by means of two hoists and 3 holding lugs. The splint is equipped with 2 trolleys. The torpedo is attached to these trolleys by means of steel bands. The torpedo is moved longitudinally by means of the aft trolley, which is equipped with gear rack and crank arm. Two transverse splints are provided for lateral movements.
		The torpedoes stored in the upper deck containers can be pulled out with twisted steel wire rope and taken from the deck by means of the portable crane. Pivot bearings installed for mounting the crane, at both sides of the deck, corresponding to each container.

	d)	Torpedo fire control system.
		The torpedo direction computing installation is intended to calculate the gyro angle based on estimated and measured values and to transmit it to torpedo tube electrically.
		The following equipment makes up the torpedo fire control installation:
		On the bridge:
		Surface sight with target bearing transmitter
		In the conning tower:
		1 Torpedo data computer
		Target bearing transmitter I
		Target bearing transmitter II
		1 Blue switch
		1 Switch box
		1 Fuse box
		In the control room:
		1 Main switch box
		1 Torpedo spread shot timer
		1 Fuse box

U-Boat Type XB	A. Ship Information	Page 51

U-boat Information	IV. Armament	4

		In the aft torpedo room:
		1 torpedo gyro angle receiver
		1 rotary amplifier for the gyro angle setting gear
		1 resistor box
		In the E-motor room:
		1 rotary converter with starter and regulator
		1 fuse box
		The torpedo firing installation enables mechanical launching at the torpedo tubes, and also electrical firing from the bridge and from the conning tower.
		The following equipment makes up the torpedo firing installation:
		On the bridge:
		1 pressure resistant firing switch
		In the conning tower:
		1 firing switch
		1 lamp board (Tube I and II)
		In control room:
		1 fuse box
		In aft torpedo room:
		1 tube distributor box
		1 lamp board
		1 resistor box

	e)	Weight compensation.
		To drain water from tubes and to compensate for the weight of launched torpedoes 2 torpedo compensating tanks are provided in the aft torpedo room.
		Torpedo compensating tank 1 Frame D 11 - 13-1/2 3.24 meters³
		Torpedo compensating tank 2 Frame D 11 - 13-1/2 3.92 meters³
		The tanks can be flooded from sea through the common hull valve on the port side and then through flood valves associated with each tank.
		The tanks are drained by the main drain pump, the auxiliary drain and trim pump, auxiliary drain pump 1 and auxiliary drain pump 2.
		Because the torpedo is heavier than the water it displaces, after the shot, a corresponding amount of water must be taken into the torpedo compensating tanks. For accurate measuring of this amount of water, a water meter is installed in each flooding line.

Page 52	A. Ship Information	U-Boat Type XB

5	IV. Armament	U-boat Information

Torpedo weight table.


	Deadweight (kg)	Volume to flood tube (liters)	Torpedo displacement (liters)	Negative or positive buoyancy (kg)

G 7a model empty	1245	370	1310.5	65
G 7a model combat weight	1540.5	370	1310.5	230
G 7e model combat weight	1573	370	1310.5	263
G 7a drill 60 at	1400	476	1254	150
G 7a drill 100 at	1438	426	1254	184
G 7a drill 200 at	1518	426	1254	264
G 7a combat 200 at	1528	426	1254	274
G 7e drill	1279	374	1306	27
G 7e combat	1603	374	1306	297

Charging and heating the electric torpedoes.

1 charging switch board and 2 main switch boards are installed in aft torpedo room for maintenance and charging electric torpedo batteries. For removing the oxyhydrogen gases and for cooling the batteries during charging a connection to the compartment ventilating system with cut off valves and vacuum gauges is installed.

(for further details see secret publication list under E Torpedoes)

U-Boat Type XB	A. Ship Information	Page 53

U-boat Information	IV. Armament	6

Gunnery.

Weapons.

The armament of the boat consists of:

1	10.5 cm cannon on the upper deck in front of the conning tower, bolted to a pyramid shaped case mount with stiffeners and welded to the pressure hull.
1	3.7 cm anti-aircraft gun on the upper deck behind the conning tower, bolted to a reinforced cylinder welded to the pressure hull.
1	2 cm anti-aircraft gun on the bridge.
1	MG C 34 (air cooled)

Ammunition.

In the non-floodable magazine (D frame - 55-1/2) below the deck in the control room the following ammunition is stored in cases:

227	rounds	10.5 cm ammunition in cans M/32
944	"	3.7 cm ammunition
1300	"	2.0 cm ammunition in cartridge boxes M 30/a
120	"	2.0 cm ammunition in a magazines
3000	"	0.8 cm ammunition for MG C 34
3000	"	0.8 cm ammunition with tracer
In the conning tower:
80	rounds	2.0 cm ammunition in 4 magazines
10	"	Signal munitions
In the upper deck (frame 82-1/2-86):
30	rounds	10.5 cm ammunition in pressure-proof cans M 32
In the conning tower casing: laterally between the cannon and conning tower under the upper deck:
2 x 32	rounds	3.7 cm in 2 pressure-proof containers in the conning tower casing in pouches of 16 rounds each
In the control room:
80	rounds	NES munitions and 180 rounds of signal munitions

Page 54	A. Ship Information	U-Boat Type XB

7	IV. Armament	U-boat Information

4)	Demolition equipment.
	In the forward mine room 2 cases each with 12 time fuses A [detonators]
	In the aft torpedo room 3 cases each with 4 scuttling charges [cartridge type] and 2 cases each with 12 demolition blocks [in containers]


5)	Small arms.
	1	MG C 34 in the petty officers room
	2	Sub machine guns in petty officers room
	3	Side arms in the munitions magazine in the control room
	6	Mauser pistols in lockers

U-Boat Type XB	A. Ship Information	Page 55

U-boat Information	V. Communications	1

V.	Communications.
1)	Visual and acoustic equipment.
	a)	Visual equipment:
		Searchlight (250 watt)
		Hand signal searchlight (each 100 watts)
		Aldis lamp
		Signal lanterns
		Signal and semaphore flags
		Star signal pistols
		Flares
		The searchlight (250 Watt) is powered by 24 V AC through the transformer from the TDC converter and is attached to a dedicated mounting in the bridge casing.
		Both hand signal searchlights (each 100 W) can be powered either by 24 V DC through the resistor from the boat light circuit or by 24 V AC through the transformer from the 1.5 kVA or 6 kVA radio rotary converter.
		These searchlights are stored in the conning tower.
		The following running lights are installed:
		Head lights
		Steaming lights
		Side lights starboard and port
		Stern lights 1 and 2
		All these lamps can be turned on by means of one common switch.
		Stern light 1 is on the bridge casing aft
		Stern light 2 is on the upper deck on the stern above main ballast tank 1.
		Either stern light 1 or stern light 2 can be turned on, they can not be turned on simultaneously.
		For firing star signals a double and a single barreled star pistol are provided in the conning tower.

Page 56	A. Ship Information	U-Boat Type XB

2	V. Communications	U-boat Information

Acoustic equipment.

Two tyfone air whistles are installed in the conning tower and they can be operated manually from the conning tower or from the bridge by means of a foot switch. The ship's bell can be mounted on the bridge.

Electronic communication equipment.

Radio installation:

The radio installation consists of long and short wave equipment.

1) Long wave:

For the longwave range a long wave transmitter with output power 150 Watt (500 - 1000 meters) is installed in the radio room. As receiver the direction finding receiver (300 - 4000 meters) is used, which is located in the radio room.

2) Short wave:

For the short wave range a short wave transmitter with output power 800 Watt (13 - 100 meters) and a short wave receiver (12 - 200 meters) are installed in the radio room. In the listening room a 40 W transmitter (18 - 60 meters) with all-wave receiver (15 - 20000 meters) is installed.

3) Longest wave:

For receiving the longest wave range, there is a direction finding receiver (12000 - 20000 meters) which uses the loop antenna. No transmitter is provided for this range.

It is possible to receive the longest waves when submerged.

UT [Underwater Telegraphy] installation.

The installation is used to send and receive waterborne sonic signals. The signal frequency is beyond the frequency of sound generated by the engines and propellers.

The UT installation consists of:

1.)	4 sound transmitters in 2 groups
	(2 each on the starboard and port side of the bow)
2.)	4 sound receivers in 2 groups
	(2 each on the starboard and port side of the bow)
3.)	Control unit, radio room
4.)	1 rotary converter, E-motor room

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U-boat Information	V. Communications	3

The transmitters and receiver groups on the starboard and port side of the bow are built in the aft part of the GHG receivers group. The connecting lines are gathered together and led through the cable socket into the pressure hull. By means of the selector switch in the control unit the transmitters or receivers on both sides of the vessel or from the one side only can be used. The control unit of the UT installation is located in the radio room. (see the classified document - Description and operation manual of the underwater sonic transmitting-receiving installation -).

The combined announcement and broadcast system.

The combined announcement and broadcast system is used to pass orders and radio broadcast transmissions.

It consists of:

Amplifier and broadcast radio receiver in radio room, 10 fixed mounted speakers, one each in:

1.	Aft torpedo room
2.	E-motor room
3.	Diesel engine room
4.	Petty officers room
5.	Control room
6.	Conning tower
7.	Radio room
8.	Officers room, Chief petty officers room
9.	Upper crew room
10.	Forward mine room

6 microphones located in

Conning tower 2 x

Aft torpedo room

E-motor room

Control room

Forward mine room

Each microphone can be connected with headphones.

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4	V. Communications	U-boat Information

Ultra short wave gear

The ultra short wave gear is a device with transmitting (with output power 10 W) and receiving capability, manufactured by Lorenz and installed in the radio room.

It enables:

toneless telegraphy

sounding telegraphy

telephony

broadcast receiving

By means of a connected telescoping antenna, it provides communication with other vessels cruising in formation. The additional ultra short wave portable transmitter and receiver, which can be found in land applications, there, with the rod aerial installed. (see the document - Ultra short wave portable transmitter and receiver -)

Direction finding and listening equipment.

Radio direction finder.

The radio direction finder is used to get own location by means of wireless signals. The direction finder is a rotatable loop antenna fitted in the front of the conning tower. The shaft of the antenna goes through the pressure hull into the control room and can be raised from there by means of compressed air. The direction finder has the property, that the wireless signal transmitter is heard the quietest (the minimum-method) when the plane of the antenna loop is aligned with its direction. To find own location, the 2 or more transmitters have to be located in such way, that the transmitted signals are quietest. The direction must be taken as a true bearing. The point of intersection of the bearings gives own location.

The radio direction finder installation consists of:

Loop antenna

Direction finder receiver

Dedicated power supply

Gyro compass repeater

The direction finder is also used as:

1) navigation device for determining the line of position

2) receiver for long and longest waves

3) device for observation of the enemy vessels movements based on their radio transmissions

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U-boat Information	V. Communications	5

		4) device for determining direction when directing to the other vessel or given position
		The control unit is located in the radio room.

	b)	K.D.B. equipment.
		The crystal rotating base gear is used to listening the noises generated by enemy vessels. It makes possible to determine the direction (range) and type of propulsion and consists of:
		1 emitter, located on the upper deck, above the forward mine room
		1 amplifier with dedicated power supply
		The control unit is located in the forward mine room.
		(see the classified document - K.D.B. Equipment- )

	c)	G.H.G. installation.
		The group listening apparatus have the same purpose as the K.D.B equipment. The installation consists of 48 receivers, 24 of which are installed on the port side and the other 24 on the starboard side of the bow. The receiver control unit is located in the listening room. (see classified document - G.H.G. Installation -)

	d)	Nah S installation. [active sonar to detect mines]
		This installation is used to detect and locate, that is, to determine the distance and direction of naval mines. It consists of a crystal oscillator fixed mounted on the bow of the boat and the case, in which all necessary auxiliary equipment is installed, and which operates the oscillator, amplifies the received signals which can be read on the scale.
		The case is located in the listening room when the boat is equipped with a radio location device [radar]. In case the boat without such device, the case is located in the control room, on the port side, near frame 60.
		For details see the description of the Nah S installation. (classified)

4)	Power supply for electronic communications equipment.
		The radio equipment is powered through the DC and AC switchboards located in the radio room. They are powered with 220 V from the auxiliary switchboard 2 installed in the E motor room.
		From the DC switchboard the following rotary converters and

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6	V. Communications	U-boat Information

		devices are powered:
		6 kVA - converter in the E-motor room
		1.5 kVA - converter in the E-motor room
		0.3 kVA - converter in the E-motor room
		UT converter in the E-motor room
		Echo sounding converter in the E-motor room
		Echo sounding device display in the control room and the conning tower.
		Transmitter switchboard in the radio room
		The 6 kVA, 1.5 kVA and 0.3 kVA (listening equipment converter) converters power the 220 V AC switchboard. To this board the following equipment is connected:
		Power supply for receivers
		Radio direction installation
		Combined announcement and broadcast system
		Coding machine (Schlüssel M) via a 6 volt transformer
		Vacuum tubes testing equipment
		40 watt transmitter
		K.D.B. equipment
		UT installation
		Depth sounding equipment
		G.H.G. installation
		Nah S installation
		Ultra short wave installation

5)	Aerials.
	The boat has the following aerials:
		Forward net deflector
		Starboard aft net deflector
		Port aft net deflector
		Extendable rod antenna
		Radio direction finding loop antenna
		Ultra short wave telescoping antenna

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U-boat Information	V. Communications	7

		All three jumping wires as well as the rod antenna can be used as transmitter and receiver aerials for short and long wave and broadcast radio equipment.
		The rod antenna is used for transmitting and receiving when the boat is at periscope depth. The direction finder loop antenna is used for direction finding and for receiving long wave transmissions.

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1	VI. Steering system and anchor installations	U-boat Information

VI.	Steering system and anchor installations.
1)	Steering system.
	The steering system consists of:
		the forward diving planes
		the aft diving planes
		the two main rudder planes parallel to each other
		the plane drive
		the plane steering lines
		the steering stations.
		All steering planes are built as balanced rudders. They are made from watertight plating on both sides (displacement rudders), with stiffeners provided between the plates. The spaces between plates are filled with well preserved wood.

	a)	Main rudder installation.
		The main rudder is twin type and can be either electrically or manually driven.
		The area of each main rudder is 3.85 meters², the maximum deflection is 30° on each side. They are driven by means of a vertical intermediate shaft, which is located outside the pressure hull, between the axes of the main rudders. This shaft is driven by a rudder spindle, by means of a connecting rod. The connecting rod passes through the pressure hull aft ending cap above the torpedo tubes in the longitudinal direction. At the intermediate shaft are mounted two arms at 90°, from which one is connected with rudder spindle through the connecting rod. The other arm (which is in the longitudinal plane of the boat) transfers its movements to both rudder planes by means of two short connecting rods.
		The electric motor drives the rudder spindle by means of a worm gear, when manual drive is engaged - from the emergency steering station in the aft torpedo room by means of bevel gear wheels. Electric drive is limited by limit switches to 28°, plane deflection is limited to 30° by means of mechanical stops.
		For electric drive there are

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U-boat Information	VI. Steering system and anchor installations	2

		2 steering stations in the control room near the projector compass and near the gyro compass. One portable steering station can be moved to the bridge or the conning tower (the portable station for both locations is provided with portable cable). The emergency steering station for manual drive is located in the aft torpedo room.
		Protection of the main rudder.
		Two arms lead from the skeg located under the stern-post to both rudders and are attached to the rudder pins. These arms protect the main rudder from hitting the bottom. All faces of the planes are rounded and all linkages are made smooth to avoid entanglement with antisubmarine nets and naval mine wires. The outer edges of dive planes are protected against naval mine wires.
		All planes are protected against corrosion (galvanic current between bronze and steel in sea water) with zinc protection plates - also boats with steel propellers.
		Main rudder angle indicator system and rudder order telegraph.
		The steering system is also equipped with an electric rudder angle indicator system. It consists of the rudder position transmitter driven by the rudder spindle and of the rudder angle receivers.
		The receivers are located:
		on the emergency steering station in the aft torpedo room
		in the E-motor room
		in the diesel engine room
		in the control room
		in the conning tower
		on the bridge (pressure proof)
		in the listening room.
		Steering commands can be transmitted by means of the rudder order telegraph from the transmitter in the control room to the receiver at the emergency steering position in the aft torpedo room.
		In addition, a mechanical rudder angle indicator is also provided.

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3	VI. Steering system and anchor installations	U-boat Information

	b)	Diving plane installation.
		The forward and aft diving planes are adapted for power and manual drive and can only be operated from the control room. The forward diving planes pair has an area of the 2 x 4.50 meters² and a maximum deflection of 25° up and 35° down.
		The aft diving plane pair is mounted aft of the propellers and has an area of 2 x 4.00 meters² and a maximum deflection 35° up and down. One hydraulic motor is installed for each plane pair, in the aft torpedo room and forward mine room respectively. The planes are driven either by the hydraulic motor by means of the worm gear, or manually from the starboard side of the control room by means of bevel gear wheels and connecting shafts.
		The required operating mode is selected by a switching lever. Switching from power to manual drive is done by compressed air piston controlled from the control room. Switching back to power drive is only possible manually at the coupling gear. The end positions of both pairs of the planes are limited by means of mechanical stops. The electric limit switches limit the hydraulic power drive at 2° before achieving the maximum deflection.
		Diving plane angle indicator system.
		Both diving planes are provided with an electric angle indicator system. The transmitter of each divining planes pair is installed at the diving planes gear.
		The following receivers are available:
		1) one for each rudder pair at the diving plane control station to starboard in the control room.
		2) in a double needled receiver for both diving planes in the conning tower
		In addition, each diving plane pair has a mechanical angle indicator installed at the diving gear in forward mine room and aft torpedo room respectively.
		In the control room, when the manual drive is engaged, the plane position is shown by means of mechanical indicators located at the control station, which are driven from the connecting shafts. These indicators can also be used when power drive is used as an emergency indicators in case of damage to the electric angle indicator system.

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U-boat Information	VI. Steering system and anchor installations	4

		In this case, hand wheels in the control room are disengaged from the connecting shafts by means of the special coupling, and both connecting shafts in the bow and aft rooms are coupled with diving planes gear by means of a special lever. Then the power drive rotates both shafts and drives the mechanical indicators in the control room.

2)	Anchor installation.
	The boat is equipped with a 700 kg weight Hall stockless type anchor with a shortened shank, which is located in the hawsehole on the starboard side. The anchor chain is 150 meters long and consists of 6 parts each 25 meters long. It is made from 28 mm chain steel as studded-chain. In the anchor chain locker the chain is attached by means of slip hooks and can be released from the inside of the pressure hull. The chain locker is located in main ballast tank 10. To keep the anchor chain in any position and for releasing anchor windlass, a chain stopper is provided between the chain sprocket and the guide drum, located beneath the upper deck.
	The anchor windlass and capstan installation are installed in the forecastle. They are driven by a driving shaft rotated by the compressed-air engine of 33 hp at 500 rpm, installed in the forward mine room.
	The time needed for the winding the totally released chain is: time = 15 minutes.
	The aft capstan installation is installed on the stern and is driven by a compressed air engine of 7 hp at 1000 rpm. Both engines are reversible. Starting, stopping as well as reversing takes place by linkage, which can be operated from the inside of the pressure hull and from the upper deck. Both capstans have spoke wreaths at theirs heads and after disengaging the power drive, can be rotated manually by means of the spokes.

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1	VII. Equipment and installations for navigation	U-boat Information

VII.

Equipment and installations for navigation.

Ship control.

During

-cruise the bridge is used as ship control station. For this purpose the pressure-proof gyro-compass repeater, pressure-proof telescope bearing, and pressure-proof main rudder angle indicator are installed there. The portable main rudder steering station can be taken on the bridge from the conning tower.

During

-cruise the conning tower is used as ship control station. The portable main rudder steering station, main rudder angle indicator, fixed-mounted gyro-compass repeater, engine order telegraph starboard and port, alarm bell activating switch and fixed-eye periscope (aft) and night periscope (forward) are located there.

The auxiliary ship control station is located in the control room. For this purpose the control room periscope, engine order telegraph starboard and port, 2 control stations for the main rudder with movable steering console (one at the gyro-compass at port side and the other near the fix-mounted gyro-compass repeater and projector compass at the forward curved bulkhead) are located there. The control station for both diving planes is also located in the control room.

Periscopes.

The boat is equipped with three periscopes:

The aft conning tower periscope (attack fixed-eye-level periscope)

The forward conning tower periscope (night attack periscope)

The control room periscope (air search periscope)

The periscopes are used to:

Control the boat as the targeting instrument during attack

Observe the water surface during submerged cruise

Navigate as a bearing instrument.

All these periscopes are equipped with a tilt mechanism for the objective, which allow for the following tilt angles:


Name	Tilt angle
	upward	downward

Aft conning tower periscope	20°	10°
Forward conning tower periscope	90°	10°
Control room periscope	90°	10°

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U-boat Information	VII. Equipment and installations for navigation	2

	All periscopes are identical in length, have the same diameter at the cylindrical part and connections for a desiccator.

	a)	Attack periscope. (aft conning tower periscope)
		The aft conning tower periscope is used as the main attack periscope during day attack approaches, the upper part of the scope is thin to make spotting difficult. It is a fixed-eye-level type, is located in the aft part of the conning tower and can be rotated together with the observer seat by means of the driving motor (hydraulic motor). The observation depth is about 14.5 meters.

	b)	Night attack periscope. (forward conning tower periscope)
		The forward conning tower periscope is the night attack scope. It is located in the conning tower, in front of the aft conning tower periscope and used as a general purpose scope. Because it is used mainly for a submerged night attacks, its objective is relatively big (to allow greater light transmission) and the diameter of the upper part is large. It can be also used as an air search periscope.
		The observation depth is about 14.5 meters.

	c)	Control room periscope.
		The control room periscope is operated from the control room. It is the air search periscope, and can be also used as the auxiliary periscope for the control the boot during submerged cruise in case of damage the conning tower periscopes or damage to the whole conning tower. Its guide bushes are located in the pressure hull plating, in the top most point of the pressure hull, forward of the conning tower. A second guide bearing installed over these bushes. The control room periscope is covered by the conning tower casing.
		The observation depth is about 14.5 meters.

	d)	Periscope drive.
		All periscopes are raised and lowered by means of a periscope winch, driven by a hydraulic motor. Two electrically driven screw pumps, installed horizontally, in the aft part of the control room, on the starboard side,

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3	VII. Equipment and installations for navigation	U-boat Information

		(one of them used as a reserve pump) pressurize the hydraulic oil from the collecting tank into 4 steel flasks of capacity 300 liters each, connected in parallel.
		Each periscope is provided with a hoisting drum driven by the hydraulic motor for raising and lowering. The fixed-eye-level periscope is also provided with additional motor for rotating the scope with the observer. These motors operate under pressures between 48-80 kg/cm².
		In each flask, there is precisely measured air cushion over the surface of the oil. Each flask is connected to the high pressure air installation to create and manage these cushions. The hydraulic motor of each periscope is powered by hydraulic oil through the main control valve, which in turn is set in corresponding position by oil running from the raising and lowering control valve. The hydraulic motor drives the gear hoisting drum, which by wrapping or unwrapping the cable raises or lowers the periscope. Each periscope is provided with a limit switch, which shorts before achieving the end position cutting off the hydraulic oil flow and stopping movement of the periscope.
		Both electrically driven hydraulic oil pumps are automatically (or manually) switched on and off by means of an automatic float switch and remote starter at the limiting pressures (48-80 kg/cm²) respectively.

3)	Compass installation.
	The compass installation consists of:
	1.	The gyro compass (by Anschütz)
	2.	The magnetic projector compass (by Askania)
	a)	Gyro compass.
		The gyro compass is installed in the middle of the control room, on the port side. It can be powered by one of two rotary converters installed beneath the ceiling of the E-motor room.
		To the master compass are connected:
		1) a bridge steering repeater (pressure proof)
		2) a bridge bearing repeater (pressure proof)
		3) a conning tower steering repeater (removable)
		4) a control room steering repeater (removable)

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U-boat Information	VII. Equipment and installations for navigation	4

		5) a control room port wall repeater for the navigator table and sonar system (fixed)
		6) a repeater in the sound room (fixed)
		7) a bearing repeater in the radio room (fixed)
		8) a steering repeater in the stern room (removable)

	b)	Projector compass.
		The projector compass is the magnetic compass. It is installed in a pressure proof casing in the front of the conning tower and through a system of mirrors and ground glasses can be viewed from the control room. Non-magnetic materials are used in a radius of 900 mm from the middle of the compass in order to eliminate the influence of magnetic fields and the influence of electric current.
		The projector compass should be used as the auxiliary direction device in case of damage to the gyro compass.

4)	Signal equipment. (See also V. 1 a )
	The signal equipment consists of:
	a)	Running lights:
		Stern light 1 (conning tower)
		Stern light 2 (stern)
		Side lights starboard and port
		Steaming lights
		Head lights
	b)	Search light equipment.
		Searchlight 24 Volt AC (250 watts)
		2 hand signal searchlights 24 Volt DC or AC (each 100 watts)

5)	Depth sounding equipment.
	a)	Echolot.
		The boat is equipped with an all-purpose depth sounding device, which has 2 main measuring ranges:
		1. 0-125 meters and 0-1000 meters
		2. for all depths.

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5	VII. Equipment and installations for navigation	U-boat Information

		Range 1: One transmitter and one receiver are provided for each of these measuring ranges, which are installed above the keel, between pressure hull frames 54/55 and 55/56.
		Range 2: 3 transmitters and 3 receivers are provided for this measuring range. The 3 transmitters are installed between frames 47/48 and the 3 receivers are installed between frames 59/60 at the keel.
		The depth sounding device is powered from the switchboard in the listening room.
		For reading the measured depth there are 2 switchable depth indicators located as follows:
		1) Control room port side
		2) Conning tower starboard side.
		Both indicators are selectable from the control room.

	b)	Elektrolot. (explosive charge)
		In this method, an explosive charge is thrown into sea and a stopwatch is started when it breaks the water surface. When the device reaches the sea bottom (the sound of explosion returns) the timer is stopped (rate of sinking is 2 meters/second).

	c)	Handlot.
		The hand lead consists of sounding line and plummet. The line is 50 meters long and is provided with marks spaced at 2 meters for reading the depth.

6)	Log installation.
	Speed is obtained by measuring the pressure difference between dynamic pressure created by boat's movement and static pressure (respective to the depth). Dynamic pressure is obtained by two nozzles located on the port and starboard side of the bow, while the static pressure is obtained by two nozzles (single bores) located on the port and starboard side of the outer shell. Each nozzle is connected by means of pipes with the master unit installed in the control room. Speed can be read there or at the electrically operated repeater in the conning tower. Separate from this repeater, a distance counter is installed in the conning tower.

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U-boat Information	VII. Equipment and installations for navigation	6

		The installation consists of:
		tubing with control manifold
		master unit (transmitter)
		repeater (receiver)
		the distance counter
		The control manifold and master unit are installed in the control room. The height of the quicksilver column is transmitted by means of a magnetic clutch. The indicator axis is coupled by variable resistance to transmit the indicator position to the log repeater and to the integrator of the distance counter.
		The repeater is installed in conning tower. The coil of the indicator is powered by 24 V current, taken from the light circuit through the voltage divider.
		The rotating indicator shows the speed on a linear 270° arc scale.
		The distance counter is installed in the conning tower. The device has two mechanical counters, the upper one showing the traveled distance. The counter is resetable. The second counter can be set to a desired distance. The optical indicator signals when that distance is traveled. The device is powered with 220 V, which by means of a voltage divider is lowered to 24 V.

7)	Alarm installation.
	(See B IX 5, c) 6)

8)	Ordering and reporting installations.
		The ordering installations make it possible to quickly pass orders and reports to the corresponding stations. They are divided into:
		Ordering and reporting installation
		Ordering installation
		Reporting installation

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7	VII. Equipment and installations for navigation	U-boat Information

	a)	Ordering and reporting installation.
		1) Voice tube connections (see Sketchbook)
		2) Engine order telegraph system
		The transmitters with answering indicator are installed in the conning tower and control room, the receivers with answering transmitters are installed in diesel engine room and in the E-motor room, one each for the starboard and port side.
		3) Sound powered phone installation
		Sound powered telephones, as they are not connected to any power line, are used for passing orders when all other ordering systems are damaged.
		Terminals are located as follows:
		1. in aft torpedo room
		2. in E-motor room
		3. in diesel engine room
		4. in the control room
		5. in the conning tower
		6. in the forward mine room

	b)	Ordering installation.
		1) Ship's announcement system
		The system is used to pass orders from the control room, conning tower, E-motor room, forward mine room and aft torpedo room to all rooms of the boat. It is also used as a radio broadcast system and is provided with dedicated amplifier. Speakers are installed in all rooms.
		2) Rudder order telegraph installation (See B IX c 4)
		3) Alarm bell and flashing light system
		Alarm activation switches: in the conning tower and control room
		Alarm bells: one in each room.

	c)	Reporting installation.
		1) Compartment ready indicating system
		The system is used to report readiness for diving of the:
		Aft torpedo room,
		E-motor room,
		Diesel engine room,
		Petty officer room, (aft battery)
		Living space forward, ((forward battery)
		Forward mine room.

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U-boat Information	VII. Equipment and installations for navigation	8

		Readiness reports are passed to the control room. The readiness indicator box in the control room has 6 lamps labeled with "Aft torpedo room ready" and so on. Reporting takes place by turning the switch located in the reporting room, which in turn lights up the corresponding lamp in the readiness indicator box in the control room.

		2). Hull closure indicating system
		The system is built on simple switch on and off principle, which indicates diving readiness by lighting lamps.
		This system has also indicator box in the control room with the following lamps:
		Exhaust gas (flap) valve starboard inner
		Exhaust gas (flap) valve port inner
		Exhaust gas (flap) valve starboard outer
		Exhaust gas (flap) valve port outer
		Diesel engine air induction trunk head valve starboard
		Diesel engine air induction trunk head valve port
		Ventilation exhaust, head valve
		Ventilation supply, head valve
		Switches for the lamps are mechanically linked to the drive of the relevant hull closure and is turned on, when the closure is CLOSED. The system is implemented as bright and dim lighting system - the lamps are lighting bright when the hull closures are closed, and dim when the closures are opened.

		3) Vent valve indicating system
		The system indicates if the vent valves are closed or opened in the control room. Each state of the vent valves is shown, when the valves are operated from the control room by means of the compressed air.
		The indicating box of the vent valves indicating system in the control room has 6 lamps, 3 push buttons for 3 main vent valves groups "aft", "amidships", "forward" and the power switch.

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9	VII. Equipment and installations for navigation	U-boat Information

		The lamps also work on the bright-dim principle, so when the vent valves are opened, the lamps light bright, when the valves are closed, they light dim. The indicator system monitors vent valves chambers for:
		1. Main ballast tank 1
		2. Main ballast and reserve fuel oil tanks 2 and 3
		3. Main ballast tanks 4 and 5
		4. Main ballast tanks 6 and 7
		5. Main ballast and reserve fuel oil tanks 8 and 9
		6. Main ballast tank 10.
		When operating the low pressure air control valve for the vent valves (i.e. for the amidships main ballast tanks), the applicable mechanically coupled vent valve indicator switch is turned on, enabling current flow for the red lamps. These lamps (i.e. for main ballast tanks 4, 5 and 6, 7) illuminate simultaneously at the vent valves indicating box in the control room and on the vent valves ordering box. This box is used when the compressed air vent valves operating pistons are damaged to order manual opening. When the compressed air driving system is not operable, the associated low pressure control valve indicator switch can be bridged with the push button at the indicating box.
		The opening of the vent valve (i.e. for main ballast tanks 4, 5 and 6, 7) causes the applicable vent valve one-pole switch to close the circuit for the white, bright lighting lamps. These lamps illuminate at the indicating box in the control room as well as at vent valves ordering box, which are connected serially. In case of damage to the associated one-pole switch, the circuit can be closed by means of a push button.

	d)	Bow and stern buoyancy tanks indicating system.
		The system is implemented with the bright-dim lamp principle, and the indicating lamps are grouped at the vent valve indicating box. The lamps illuminate brightly when the vent valves are opened.

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U-boat Information	VII. Equipment and installations for navigation	10

	e)	Rudder angle and shaft revolution indicator system.
		These systems allow for the continuous viewing of the position of the main rudder and diving planes as well as shaft revolutions in the conning tower, control room and a few more stations (listening room, diesel engine room). The main rudder angle indicator is located on the bridge (in a pressure-proof casing).

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1	VIII. Safety and rescue installations	U-boat Information

VIII.	Safety and rescue installations.
1)	Installations for submerged and surfaced boat.
	a)	Emergency lighting.
		There are 11 lamps in pressure-proof cases, automatically switched on when the light circuit is not operating, powered by 2-cell, small batteries.
		Distribution:
		1 lamp in aft torpedo room
		1 lamp in E-motor room
		2 lamps in diesel engine room
		1 lamp in the galley
		1 lamp in the officers room
		1 lamp in the control room
		2 lamps in the forward living space
		1 lamp in the forward mine room

	b)	Hand lamps.
		10 portable, battery powered hand lamps (4 V) are also provided as emergency lightning.

	c)	Fire extinguishers.
		7 extinguishers are provided on board for fire fighting (CO2 extinguishers).
		Aft torpedo room
		E-motor room
		Diesel engine room
		Petty officers room
		Control room
		Forward living space
		Forward mine room.
		In the case of a fire on the upper deck, the upper deck wash line can be used.
		In the case of a large fire, air access must be cut off by closing the compartment.

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U-boat Information	VIII. Safety and rescue installations	2

	d)	Flooding installation. (see B III 5)

	e)	Drainage installation.
		The drainage installation includes:
		1. Main drain pump in the control room
		2. Auxiliary drain and trim pump in the control room
		3. Auxiliary drain pump 1 in the aft torpedo room
		4. Auxiliary drain pump 2 in the forward mine room
		5. Emergency drain pump
		6. The electrically driven auxiliary cooling water pump in the diesel engine room (only to drain the diesel engine room).
		(for more drain installation B III 1, 2 and 3)

	f)	UT installation.
		This is used for underwater communication during submerged cruise.
		(for more see Communications A V 2b)

	g)	Emergency steering gear.
		The emergency steering station with the mechanical transmission to the main rudder is located in the aft torpedo room.

	h)	Emergency escape gear and diving suit.
		72 sets of emergency escape gear are provided on board. The escape gear is so located, that during submerged cruise, in case of emergency, there is a sufficient number of sets in each compartment for each crew member at their diving stations.
		Also, two full diving suits (one with and one without weights) are provided on board. Moreover there is 1 simple diving suit for usage with emergency escape gear. 74 breathing masks with carrying bags for the sodium hydroxide cartridges are provided.

	i)	Life rafts and mats.
		2 Life rafts with buoys are stored at the upper deck and can be released from the inside of the boat.

	k)	Damage control materials.
		(see IX 3c)

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3	VIII. Safety and rescue installations	U-boat Information

Installations for surfaced boat.

Battery ventilation.

The batteries are ventilated while charging by means of the battery blower, located in control room, on the starboard side. The intake and exhaust air fans installed in the diesel engine room can also be used for that purpose.

Emergency vent valves.

Each main ballast tank (except main ballast tank 1) and each main ballast and reserve fuel oil tank starboard and port, there is an emergency vent valve located at joint of the tank cover with vent trunk, which is operated from the inside of the boat.

These valves are located as follows :

Aft torpedo room	2 Emergency vent valves for main ballast and reserve fuel oil tank 2 starboard and port - at D frame 5
E-motor room	2 Emergency vent valves for main ballast and reserve fuel oil tank 3 starboard and port - at D frame 16
Diesel engine room	2 Emergency vent valves for main ballast tank 4 starboard and port - at D frame 28
	2 Emergency vent valves for main ballast tank 5 starboard and port - at D frame 35
Control room	2 Emergency vent valves for main ballast tank 6 starboard and port - at D frame 49
Forward living space	4 Emergency vent valves for main ballast tank 7 starboard and port and main ballast and reserve fuel oil tank 8 starboard and port - at D frame 56-1/2 and at D frame 67
Forward mine room	4 Emergency vent valves for main ballast tank and reserve fuel oil tank 9 starboard and port and main ballast tank 10 starboard and port - at D frame 73-1/2 and at D frame 86-1/2

Coaming.

The torpedo hatch in the aft torpedo room, access hatches in the aft torpedo room (on the starboard side), galley, forward living room and forward mine room are provided with protective coamings against entry of water. These are made from steel plates and extend from the pressure hull up to the bottom of the wood finish of the upper deck or upper edge of the mine shafts casing respectively. The coaming is provided with a drain gate valve. The coaming of the torpedo hatch is located in such way, that it does not prevent torpedo loading.

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U-boat Information	VIII. Safety and rescue installations	4

	d)	Life buoy and dinghy.
		Available aboard:
		1 Dingy with an outboard motor stowed in a pressure-proof container
		2 Marcks life rafts/buoys
		2 Life rings on the outside of the bridge.

	e)	Life jackets.
		35 standard life jackets and 20 pilot life jackets (inflated with the compressed air from the attached flask) are provided at all diving stations.

	f)	Railing and tethers.
		The railing is installed on the upper deck on both sides and leads from the bow to the stern. The railing pennants are mounted in railing supports by means of clamping bolts. Demounted railing can be stowed in the upper deck casing. At the 10.5 cm deck cannon, at both sides of the conning tower and at the 3.7 cm cannon the railing is fixed mounted.
		Tethers and safety belts provided for use by the bridge watch and the crew operating the deck gun while cruising in stormy seas.

	g)	Inflatable boat.
		The inflatable boat is 9.5 meters long and 2.4 meters wide.

3)	Installations for submerged boat.
	a)	Compartmentation.
		Four spherical, pressure and water proof bulkheads located at frames 13-1/2, 45-1/2, 55-1/2 and 70-1/2 divide the pressure hull into 5 pressure-proof compartments (I, II, III, IV, V). Compartment II is further divided by two water-tight bulkheads at frames 22 and 35-1/2 into 3 water-tight rooms, so the entire pressure hull has 7 water-tight rooms (Rooms 1, 2, 3, 4, 5, 6 and 7).

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5	VIII. Safety and rescue installations	U-boat Information

	b)	Air purification system.
		1. Oxygen system
		The oxygen system is used to enrich the air with the oxygen. 16 oxygen flasks with capacity 50 liters each and total capacity of 800 liters of oxygen under a pressure of 150 kg/cm² are located as follows:
		5 oxygen flasks in aft torpedo room
		5 oxygen flasks in the control room
		6 oxygen flasks in forward mine room
		The distribution installation consists of:
		Aft torpedo room:
		1 oxygen distributor
		1 oxygen supplementing regulating valve
		1 oxygen replenishment station for emergency escape gear
		Control room and forward mine room:
		As in the aft torpedo room.
		Conning tower:
		1 oxygen supplementing regulating valve
		The oxygen intake connection is located on the upper deck, at the starboard side of the conning tower.

		2. Air purification system
		The air intake and exhaust fans circulate air inside the boat. Doing so, the air is forced through the air purifiers, where the CO2 is absorbed. The purified air is then released into the rooms. During silent running, these two fans can be replaced by two noiseless, small blowers. These are located in the control room and in the E-motor room, installed on the rubber mountings.

		3. Sodium hydroxide cartridges
		590 sodium hydroxide cartridges are at hand. They chemically bind CO2 in exhaled air. These cartridges can be used for air purification by connecting them to the air exhaust ducts as follows:
		8 units in retaining racks in aft torpedo room
		8 units in retaining racks in control room
		8 units in retaining racks in forward mine room

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U-boat Information	VIII. Safety and rescue installations	6

The remaining cartridges are stored in dedicated holders and are evenly distributed over all rooms of the boat.

Compressed air and emergency blowing manifold.

1. Compressed air distribution:

	High pressure manifold	Control room amidships,
		Aft torpedo room
	Medium pressure manifold	Control room starboard
	Low pressure manifold	Control room starboard

2. Emergency blowing manifold

The regulating valves of the blowing distributors for the forward, midship and aft group are built as check-valves, so even when these valves are opened, blowing is possible from the end rooms. The cones of cone valves are closed by the air flowing from the emergency blowing manifolds located in the end rooms.

1 Emergency blowing manifold in aft torpedo room

1 Emergency blowing manifold in forward mine room

1 Diver emergency blowing manifold

In the front of the conning tower, at the upper deck, just forward of the magnetic compass casing there is a diver emergency blowing manifold with cut-off valves for main ballast tanks 1, 4, 5, 6, 7, 10 and main ballast and reserve fuel oil tanks 2, 3, 8, 9. Separate valves are provided for main ballast tank 10 and fuel oil tanks 1a port and 2a port and fuel oil tanks 1a starboard and 2a starboard. Named tanks can be blown from the outside by means of this installation, if necessary, with the help of a diver.

Emergency air supply system.

2 Hull valves for emergency air supply and emergency air exhaust in the aft torpedo room

2 Hull valves for emergency air supply and emergency air exhaust in the control room

2 Emergency air exhaust selector valves in the control room and conning tower

2 Hull valves for emergency air supply and emergency air exhaust in the forward mine room

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7	VIII. Safety and rescue installations	U-boat Information

Air trap.

Hatches in the aft torpedo room - access hatch (not the torpedo loading hatch), in the control room, in the forward living space and in the forward mine room are provided with coamings which extend downward, which in the case of escaping from the flooded compartment trap some of the air.

The distances between the bottom edge of the coaming and the deck plating:

Aft torpedo room	1570 mm
Galley (air trap extended)	1850 mm (otherwise 1970)
Control room	1650 mm
Forward living space	1780 mm
Forward mine room	1650 mm

All of these coamings (except the one in the galley) are not extendable downward.

Net deflector.

The forward net deflector is made of stranded wire, which is extended from the bow to the conning tower, while the aft deflector consists of two stranded wires extended from the stern to the conning tower.

Net cutter.

At the upper part of the bow and at the bottom part of the stem post two net cutters are installed. The cutters are not protected by any cover.

Compartment ready indicating system.

The lamp box indicating the readiness for dive of each compartment is located in the forward part of the control room, at the starboard side. When the compartment reports readiness, the corresponding lamp lights up.

Hull closure indicating system.

The lamp box of the large hull closure indicating system is located in the forward part of the control room, at the starboard side. When the closure is closed, the corresponding lamp lights "bright".

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U-boat Information	VIII. Safety and rescue installations	8

		They are associated with:
		2 diesel air intake head valves
		2 inboard exhaust gas valves starboard and port
		2 outboard exhaust gas valves starboard and port
		1 ventilation air supply valve
		1 ventilation air exhaust valve.

	k)	Vent valve indicating system.
		The lamp box of this system is also located in the forward part of the control room, at the starboard side, at the curved bulkhead. When the vent valves of the main ballast and main ballast and reserve fuel oil tanks are "open", the lamps light "bright". When the vents are closed, they glow powered with lower voltage. When the vents are opening, the lamps are off.

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1	IX. Damage Control	U-boat Information

IX.

Damage Control.

General.

Damage control parties.

To increase the safety of the boat, hull, electrical and machinery parties are formed. These parties have following tasks:

Removing leaks due to enemy action; removing damage to machinery and electrical installations due to enemy action;

Passing orders through the boat;

Reducing noise during approach and evasion and thereby improving depth keeping, which is especially demanding in the presence of the enemy;

Damage control parties are formed from off duty crew members.

Balancing the boat.

The boat is so designed, that when

in trim condition A with standard load (main ballast and reserve fuel oil tanks filled with water) and empty regulating and reserve fuel oil tanks, regulating tanks and negative tanks (mine compensating tanks 1-4 are filled with ~30 m³ of water),

at sea water of density = 1.003 it has 0 tons of buoyancy.

The excess buoyancy which - when

with trim condition B - is 29.98 tons. It is compensated by loading on board additional supplies:

7.28 tons	Lubricating oil (0.91)
2.00 tons	Fresh and wash water
5.30 tons	Provisions
15.40 tons	Water in regulating tanks

Note: The average density of seawater at the ocean surface is 1.025 grams/ml. Seawater is denser than both fresh water and pure water (density 1.0 grams/ml at 4 °C (39 °F)) because dissolved salts add mass without contributing significantly to volume. Sea water density varies with salinity and temperature from about 1.020 - 1.030 grams/ml.

The water density 1.003 cited above (at which the boat would have 0 buoyancy) is very low and would never be encountered by the boat while it was operating in sea water.

The density of sea water in the Baltic is significantly lower (as low as 1.005 at salinity 7.5%) due to fresh water from rivers than in the North sea (1.025 at salinity 35%).

U-Boat Type XB
A. Ship Information
Page 85

U-boat Information
IX. Damage Control
           2

The following loading proportions are established:

Supply

Trim Condition A

Trim Condition B

Fuel oil (density = 0.87) (including fuel oil in the gravity tank)
121.200 tons

356.483 tons

Lubricating oil
9.130 tons

16.410 tons

Provisions
6.200 tons

11.500 tons

Fresh and wash water
4.530 tons

19.330 tons

When combat ready, the larger load (trim condition B) is used.

c) Reserve buoyancy.

Reserve buoyancy is created by removing water from the boat structure. When submerged, it is destroyed by flooding the main ballast tanks and main ballast and reserve fuel oil tanks.

The reserve buoyancy in:

Trim Condition A (main ballast and reserve fuel oil tanks empty) is 652.6 meters³

Trim Condition B (main ballast and reserve fuel oil tanks filled with fuel oil) is 414.6 meters³

2) Weights and trim adjustment with water flooding.

a) Leakage into external tanks with the boat surfaced.

Leaks into external tanks are not dangerous for the boat. The reserve buoyancy in each case gives enough displacement, which also is not affected by trim change except when accidentally all main ballast and reserve fuel oil tanks and main ballast tanks are so damaged that they are completely flooded. In such case, the boat is floatable only with empty regulating and reserve fuel oil tanks, regulating tanks and negative buoyancy tanks.

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3	IX. Damage Control	U-boat Information

Buoyancy amounts with flooded individual external tanks:


Leak	Capacity meters³	Remaining buoyancy in meters³
Leak	Capacity meters³	Trim Condition A	Trim Condition B

Main ballast tank 1	44.30	608.30	370.30
Main ballast and reserve fuel oil tank 2	43.25	609.35	371.35
Main ballast and reserve fuel oil tank 3	58.20	594.40	356.40
Main ballast tank 4	78.40	574.20	336.20
Main ballast tank 5	88.95	563.65	325.65
Main ballast tank 6	88.20	564.40	326.40
Main ballast tank 7	75.75	576.85	338.85
Main ballast and reserve fuel oil tank 8	69.05	583.55	345.55
Main ballast and reserve fuel oil tank 9	67.55	585.05	347.05
Main ballast tank 10	39.00	613.60	375.60

To avoid a large decrease in seaworthiness when leakage into external tanks occurs, to remove the inconvenient trim and heel of the boat, counter ballasting which does not threaten the buoyancy of the boat is to be used.

In cases where to relieve the boat fuel oil is blown from the fuel oil tanks, the values given in the following table are applicable.

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U-boat Information	IX. Damage Control	4

Weight and trim changes with leaks in external tanks.


		Water			Fuel oil density = 0.87

Tank	Arm + meters	Weight tons	Moment + meter tons	TU cm	Weight tons	Moment + meter tons	TU cm

Main ballast tank 1	-34.75	44.3	-1540	67
Main ballast and reserve fuel oil tank 2	-26.92	43.25	-1160	50	37.5	-1010	44
Main ballast and reserve fuel oil tank 3	-20.27	58.2	-1180	51	50.5	-1030	45
Fuel oil tank 1a	-15.40	83.2	-1280	56	72.3	-1110	48
Main ballast tank 4	-10.43	78.4	-818	35
Main ballast tank 5	-4.87	99.95	-433	19
Regulating and reserve fuel oil tank 1	-0.60	29.32	-17
Mine tank 1+2	-1.24	15.0	-19
Regulating tank 2	+2.11	26.6	+56	2
Mine tank 3+4	+0.54	15.0	+8
Main ballast tank 6	+6.04	88.2	+532	23
Main ballast tank 7	+11.52	75.75	+875	38
Fuel oil tank 2a	+15.86	54.9	+870	38	47.7	+760	33
Main ballast and reserve fuel oil tank 8	+19.72	69.05	+1360	59	60.0	+1180	51
Main ballast and reserve fuel oil tank 9	+26.76	67.55	+1810	79	58.6	+1570	68
Main ballast tank 10	+30.36	39.00	+1180	51

TU = depth difference [tauchunterschied]

Leakage into pressure hull with the boat surfaced.

Small leaks (see paragraph 3 d) can be removed by means of the hand drain pump. Large leaks which lead to flooding the room are restricted by the watertight bulkheads. With one fully flooded room (not compartment) the trim is held within tolerable limits (the largest depth difference between stem post and stern post is 1.48 meters with fully flooded forward mine room).

When the leakage occurs, counter ballasting must be taken immediately. This step is necessary to avoid the appearance of large trim changes. Thereto in case of leak, counter ballasting must be adjusted adequately to the situation. When large trim changes appear, main ballast tanks 1 and 10 can not be flooded, because the flood slits are above the water surface. The flooding of main ballast tanks 1 and 10 is appropriate as counter ballasting only when the boat has greater immersion (see the table).

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5	IX. Damage Control	U-boat Information

Weight and trim changes with leaks in internal rooms.


Room	Weight tons	Arm + meters	Moment + meter tons	TU cm

Aft torpedo room	75	-28.80	-2160	94
E-motor room	95	-20.75	-1970	86
Diesel engine room	153	12.00	-1840	80
Galley and petty officer room	99	-2.70	-267	11.5
Control room	100	+4.95	+495	22
Forward living space	175	+14.50	+2540	111
Forward mine room	115	+26.40	+3040	148

Measures for leaks in internal rooms.


		MBT	MB/RFOT		FOT	MBT				FOT	MB/RFOT
Leak	Trim Cond.	1	2	3	1a	4	5	6	7	2a	8	9	10	RB + tons	TM + tons	TU cm

Aft torpedo room	A													649	-1050	-44

	B													427	-120	-5

E motor room	A													629	-860	-37

	B													414	+70	+3


Diesel engine room	A													571	-730	-32

	B													349	+200	+9

Galley, PO room,	A	No immediate measures necessary												553	-267	-11

Battery	B													315	-267	-12

Control room	A	No immediate measures necessary												552	+495	+21

	B													314	+495	+22

Forward living room	A

	B

Forward mine room	A

	B

	Flood
	Blow
	Fuel tank filled with oil

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U-boat Information	IX. Damage Control	6

		It should be noted, that as the pressure inside the boat increases, the depth meter no longer shows the true diving depth. It shows less depth, according to the pressure difference between the water pressure and the pressure inside the hull. Depth must also be controlled by the Bourdon pressure gauge, periscope or the conning tower air supply valve.

	c)	Leakage into external tanks and into pressure hull with the boat surfaced.
		The narrow compartmentation of the boat provides great safety in case of leakage. In the following tables is given, that always both sides are equally flooded. In case of one-side damage, the other side has to be flooded to remove the list.
		In case of small list counter ballasting is not necessary - the boat keeps the better trim and buoyancy relationships.
		The depth difference between the stem post and stern post has similar values as occurs during immersion and trim changes under normal conditions. When the upper edge of the tanks due to large trim angle and immersion come under the water surface, new, reduced stability values related with the large trim angles must be computed. In the tables values are computed assuming all tanks are fully filled. When the tanks are filled partially, the weight and moments must be estimated.

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7	IX. Damage Control	U-boat Information

		Weight and trim changes with leaks in internal and external spaces.

Aft.


Space	Trim Condition	Weight tons	Arm + meters	Moment + meter tons	Trim condition without countermeasures

Aft torpedo room	A	75	-28.8	-2160	Condition B: not floatable
MBT 1	B	44	-34.8	-1540
		119		-3700

Aft torpedo room	A	75	-28.8	-2160	not floatable
MBT 1		44	-34.8	-1540
MBT/RFOT 2		43	-26.9	-1160
MBT/RFOT 3		58	-20.3	-1180
		220		-6040

	B	133		-6040

E-motor room	A	95	-20.75	-1970
MB/RFOT 3		58	-20.3	-1180
		153		-3150

	B	103		2120

E-motor room	A	95	-20.75	-1970	not floatable
MB/RFOT 2		43	-26.9	-1160
MB/RFOT 3		58	-20.3	-1180
		196		-4310

	B	109		2270

Diesel engine room	A	153	-12.0	-1840	Condition B: not floatable
FOT 1a	B	11	-15.40	-170
		164		-2010

Diesel engine room	A	153	-12.0	-1840	Condition B: not floatable
FOT 1a		11	-15.4	-170
MBT 4	B	78	-10.4	-811
		242		-2821

Diesel engine room	A	153	-12.0	-1840	not floatable
MBT 4	B	78	-10.4	-818
MBT 5		89	-4.9	-436
		320		-3094

Petty Officers room	A	99	-2.70	-267	not floatable
MBT 5	B	89	-4.9	-436
		188		-703

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U-boat Information	IX. Damage Control	8

		Weight and trim changes with leaks in internal and external spaces.

Forward.


Space	Trim Condition	Weight tons	Arm + meters	Moment + meter tons	Trim condition without countermeasures

Control room	A	100	+4.95	+495
MBT 6	B	88	+6.04	+532
		188		+1027

Forward living space	A	175	+14.50	+2540	Condition B: not floatable
MBT 7	B	76	+11.52	+875
FOT 2a		7	+15.86	+111
		258		+3526

Forward living space	A	175	+14.50	+2540
MBT 7		76	+11.52	+875
FOT 2a		7	+15.86	+111
MB/RFOT 8		69	+19.72	+1360
		327		+4886

	B	267		+3700

Forward mine room	A	115	+26.40	+3036
MB/RFOT 9		68	+26.76	+1820
		183		+4856

	B	124		+3280

Forward mine room	A	115	+26.40	+3036
MB/RFOT 9		68	+26.76	+1820
MB/RFOT 8		69	+19.72	+1360
		252		+6216

	B	133		+3460

Forward mine room	A	115	+26.40	+3036
MBT 10		39	+36.36	+1418
MB/RFOT 9		68	+26.76	+1820
		222		+6274

	B	163		+4460

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9	IX. Damage Control	U-boat Information

Measures for leaks in internal rooms with adjoining external tanks.


		MBT	MB/RFOT		FOT	MBT				FOT	MB/FOT
Leak/ Room	Trim Cond.	1	2	3	1a	4	5	6	7	2a	8	9	10	RB + tons	TM + tons	TU cm	Rmks.

Aft torp.	A													538	-765	-32	able to

	B													455	-550	-24	float

Aft torp.	A													426	-580	-25	"

	B

Aft torp.	A													328	-327	-15	"

	B													238	-615	-28

E-motor	A													503	-230	-10	"

	B													421	0	0

E-motor	A													391	-30	-1	"

	B													338	+240	+11

Diesel	A													420	-200	-9	"

engine	B													338	+30	+1

Diesel	A													303	+417	+18	"

engine	B													184	+80	+4

Diesel	A													336	-170	-7	"

engine	B													254	+60	+3

Petty Off.	A													464	-700	-30	"

	B													264	+410	+18

Control	A													421	-130	-5	"

	B													286	-150	-7

F. Living	A													248	-335	-16	"

	B													217	-40	-2

F. Living	A													104	+185	+8	"

	B													83	-230	-10

F. mine	A													371	+210	+9	"

	B													353	-200	-9

F. mine	A													224	+750	+33	"

	B													207	+340	+15

F. mine	A													254	+825	+38	blow WT bow

	B													237	+400	+18	blow WT bow

	Leaking external space
	Fuel tank filled with oil
	Flood
	Blow

U-Boat Type XB	A. Ship Information	Page 93

U-boat Information	IX. Damage Control	10

Additional measures for weight reduction and trim adjustment.


Name	Location	Volume meters³	Arm + meters	Moment water + meter tons	Moment oil meter tons	Trim change in cm TU

Trim tank 1	starboard	3.94	-27.52	-108.5		5
Trim tank 2	port	3.94	-27.52	-108.5		5
Torpedo compensating tank 1	starboard	3.240	-25.04	-81.1		3.5
Torpedo compensating tank 1	port	3.920	-24.90	-97.6		4
Waste water tank 1	starboard	0.760	-24.33	-18.5		1
Water distillate tank 1	centerline	0.195	-20.06	-3.9
Water distillate tank 2	centerline	0.580	-19.49	-11.3
Water distillate tank 3	port	0.215	+33.15	+7.13
Fuel oil gravity feed tank	centerline	2 x 0.600	-13.33		13.9
Dirty lubricating oil tank	centerline	1.360	-15.09		18.7
Lubricating oil collecting tank	starboard	1.360	-11.89		14.7
Lubricating oil collecting tank	port	1.360	-13.49		16.7
Fuel oil collecting tank	centerline	0.680	-10.69		6.6
Waste water tank 2	centerline	0.625	-7.30		0.5
Fresh water tank 1	centerline	0.780	-6.47
Wash water daily supply tank		0.060	-5.69
Lubricating oil supply tank 1	starboard	4.000	-4.34		15.1
Lubricating oil supply tank 2	port	4.000	-4.34		15.1
Lubricating oil supply tank 3	starboard	4.000	-0.43		1.6
Lubricating oil supply tank 4	port	4.000	-0.43		1.6

Stern buoyancy tank		8.4	-40.42

TU = depth difference [tauchunterschied]

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13	IX. Damage Control	U-boat Information

on an even keel so that no dangerous trim moments are caused by the free water surfaces. In addition to the main ballast tanks and main ballast and reserve fuel oil tanks, the fuel oil tanks, regulating and reserve fuel oil tanks, regulating tanks, negative tanks, bow and stern buoyancy tanks can be also be blown.

Sealing the compartments.

All pressure and watertight bulkheads are to be shut.

Shut isolating valves on voice tube connections:

In aft torpedo room:	Voice tube to control and conning tower plus their whistling tubes;
In E motor room:	Voice tube to the control room
In diesel engine room:	Voice tube to the control room
In control room:	Voice tube to the diesel engine room
	Voice tube to the E-motor room
	Voice tube to the aft torpedo room
	Whistling tube to the aft torpedo room
	Whistling tube to the forward mine room
	Voice tube to the forward mine room
	Voice tube to the radio and listening rooms
	Voice tube to the forward living room
In conning tower:	Voice tube to the radio and sound rooms
	Voice tube to the Commander's room
	Voice tube to the bridge
	Whistling tubes 2
In forward living room:	In the Commander's room to the conning tower
	In the radio room and listening room to the conning tower
	In the radio room and listening room to the control room
In forward mine room:	Voice tube to the control room, conning tower
	Whistling tube to the control room, conning tower

Sealing leaks.

7 leak sealing kits are available, 1 in each watertight compartment.

Their contents are:

	1	Hammer
	1	Pincher pliers

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U-boat Information	IX. Damage Control	14

	1	Chisel
	1	Pry bar
	1	Flat chisel
	1	Cross-cut chisel
	2	Clamps
	1	Adjustable wrench
	2	Tapered punches
	1	Hatchet
	1	Crosscut saw with guard
	30	Nails (3" to 5")
	20	Leak plugs (spruce, various sizes)
	20	Wedges (beech, flat, various sizes)

Also at hand in the following rooms are:

In the aft torpedo room:

2 timbers 10 x 10 x 400 cm

2 boards 75 x 30 x 4 cm

In the diesel engine room:

4 timbers 10 x 10 x 400 cm

2 boards 75 x 30 x 4 cm

In the forward mine room:

4 timbers 10 x 10 x 300 cm

2 boards 75 x 30 x 4 cm

Leakage with the boat lying on the bottom.

The same measures as in paragraph IX 2 d are to be conducted. The tables can be used as a basis for estimation of the boat's buoyancy - as long as the pressure-proof compartmentation is stated (aft torpedo room, control room, forward living space, forward mine room). Additionally it must be noted, that if the boat is lying on a sand-type sea bottom in such way that the keel is not washed out by the water. The boat is sucked down and with the corresponding force the keel of area 90 meters² presses on the bottom. Weight relief (blowing) is effective only when the boat is trimmed or heeled or the additional weight (water from the leaks) is removed.

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15	IX. Damage Control	U-boat Information

Pumping.

The performance of main drain pump is 160 meters³/hour at a pressure head of 10 meters H₂O in the operation mode II (one stage) and 58 meters³/hour at a pressure head of 105 meters H₂O in the operation mode I (three stage) without pipelines flow resistance influence. Due to flow resistance the highest performance is only 75 meters³/hour at a pressure head of 10 meters H₂O in the control room, 60 meters³/hour in forward mine room and 55 meters³/hour in the aft torpedo room.

Its performance allows for pumping the leaks through the holes of the following cross sections:


Water depth in meters	Pump operating mode	Leak cross section in cm²
Water depth in meters	Pump operating mode	in aft torpedo room	in the control room	in the forward mine room

5	II	24.0	32.0	26.7
10	II	12.2	17.5	14.0
15	II	4.8	7.7	4.8
25	I	8.9	8.9	8.9
50	I	6.0	6.3	6.0
100	I	4.0	4.5	4.1

Weight relief.

(See paragraph IX 2 c) (Additional measures for weight reduction and trim adjustment)

Escape from a sunken boat.

Escape procedures.

As soon as it becomes clear, that the boat is not able to surface, immediately, without waiting for any help, the crew prepares for escape. Pressure equalization takes place by intentional flooding of the pressurized compartment or the entire boat. For closures which should be opened see paragraph 4 d. Escape from the control room takes place via the conning tower, from the after ship through the torpedo loading hatch, and from the fore ship through officers' room hatch and forward mine room hatch. All hatches except the torpedo loading hatch are provided with air traps. After beginning flooding, the cover of the escape hatch is unscrewed and the hand bar with the catch is

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U-boat Information	IX. Damage Control	16

		fixed, so that when the pressure is equalized, the cover can be raised and flooding process up to the air trap will be accelerated. The crew is to gather near the hatch, because after flooding orientation becomes difficult. The crew should stay high.
		During preparations to escape and final awaiting all available measures should be taken to prevent the increasing of the carbon dioxide level in the remaining air, as the air purification system is not operable Each crew member must breathe through the sodium hydroxide cartridges, must not make unnecessary movements, the unemployed must lie down.

	b)	The flooding of the boat and effects on the crew.
		All available means must be used to flood the boat as quickly as possible. Staying in a flooded boat at sea pressure is limited by influence of chlorine gas and hazard of the bends, so it should be as short as possible. For flooding options see paragraph 4 d.
		During flooding up to the actual escape the crew stay in the air bubble - ready with the emergency escape gears - and breathe the compressed air. To save the oxygen and minimize the harmful influence of pressurized oxygen, the emergency escape gear must be used for the first time just before actual escape, or in case of increasing carbon dioxide level or in presence of the chlorine gas.
		The pure water pressure or increased air pressure is meaningless for the men staying under over-pressure. Slow accustoming is not required. At fast pressure increase, ear ache can appear. However this condition does not lead to ear damage and hearing ability will soon come back. So these symptoms may not be taken into account while flooding.

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17	IX. Damage Control	U-boat Information

Chlorine gas is created when the batteries are flooded with sea water. It can reach poisonous levels in the air remaining in the room. This gas is immediately noticeable because of its strong, piercing smell and irritating effect on the airways (cough) and forces the use of the emergency escape gear as well as putting on goggles.

While flooding, together with the pressure inside the boat, the partial pressure of the carbonic acid in the air remaining in the room, also increases (the partial pressure of the gas it is the % content in the air times absolute pressure). The influence on the organs is caused by the partial pressure of the gas - not its concentration. When increased partial pressure of the carbonic acid due to flooding is noticeable by difficulty breathing, the emergency escape gear must be used. 2% CO₂ under the pressure of 5 at (corresponding pressure at the 40 m) corresponds i.e. 10% CO₂ under atmospheric pressure.

Under the over-pressure, an increased amount of nitrogen is entering to the body from the breathing air. When it is in sufficient amounts in the blood and in the tissues of the body, then, when the pressure rapidly drops, as during the surfacing with the emergency escape gear, it is released in the organs and causes the bends. The appearance of the bends depends on: 1) depth, from which escaping, 2) time of staying under the pressure corresponding to the depth, 3) the speed of surfacing. The following staying times under the pressure corresponding to water depth and breathing the air remaining in the room

Water depth	Staying Time

30 meters	37 minutes
45 meters	18 minutes
51 meters	17 minutes
56 meters	14 minutes
62 meters	13 minutes

do not cause the symptoms of the bends, when emergency surfacing speed is not greater than 15 meters/minute, i.e. normal, medium surfacing speed.

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U-boat Information	IX. Damage Control	18

The hazard of the bends necessitates flooding the boat as fast as possible and leaving the boat immediately after pressure equalization.

When escaping from a sunken boat from a depth greater than 20 meters, oxygen can be used only when diluted with air. The following rules apply:

	1.	Before flooding:
		Put on the escape gear when ordered.
		Breath out the boat's air into the breathing bag, till the bag is half full.
		Close the mouthpiece.
		Add the oxygen, until the bag is three-quaters full.
		(pure oxygen without air only at depths down to 20 meters)
	2.	Before escaping and when chlorine gas present:
		Put the mouthpiece into the mouth.
		Put on the nose-clamp.
		(the over-pressure valve must be loosened)
	3.	While escaping:
		Breathe out the air through the corner of the mouth.
	4.	After surfacing:
		Secure the over-pressure valve.

Escaping from the boat.

Immediately after pressure equalization, the boat must be left in sequence order.

The emergency escape gear is put on according to instructions, i.e. after emptying the breathing bag and while breathing out. The securing cap of the over-pressure valve must be detached.

Escaping is possible with and without escape gear. The air in the lungs and airways is under pressure corresponding to the depth. Thus, the lungs always contain a sufficient amount of oxygen for escape, so that no difficulties in breathing occur.

While ascending, the air in the respiratory organs extends due to pressure reduction. This excess air must be expelled; if this is not performed, by forced breath holding, over-pressure in lungs arises, which leads to fainting and thwarts rescue.

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19	IX. Damage Control	U-boat Information

Surfacing, due to hazard of the bends, should be performed as slowly as possible. Therefore, to decrease the buoyancy, the breathing bag must be filled with only a small amount of gas and excess air has to be breathed out through the corner of the mouth. Surfacing can be slowed by limb movements and in any case must not be sped up by swimming gestures.

After-treatment for rapidly decompressed crews is always required. They must stay in the pressurized chamber or U-boat rooms at 0.9-0.3 at over-pressure, breathing pure oxygen (emergency escape gear) for 10 min while performing physical activity.

Flooding options.

Considering previously discussed influences of pressurized nitrogen and oxygen, on type XB U-boats the following openings can be used for rapid flooding:

1.	Flooding the aft torpedo room.		Narrowest Flood Opening
			mm ø	cm²
	a)	Auxiliary drain pump 1, remove discharge to sea hull valve and auxiliary to sea drain valve, open hull valve	100	78.5
	b)	Remove WC check valve, open exterior cock group, open inner valve group	70	38.5
	c)	Outer door torpedo tubes 1 and 2 open, remove torpedo compensating tanks 1 and 2 man holes, open flooding and drain lines tube 1	70	38.5
		Open flooding and drain lines torpedo tube 2, hull valve for flooding torpedo compensating tanks	70	38.5
				194 cm²


Water depth in meters	10	20	30	40	50	60	70	80	90

Flooding time in minutes	10	8.3	7.4	6.5	5.7	5.2	4.8	4.5	4.3

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U-boat Information	IX. Damage Control	20

2.	Flooding the diesel, E-motor and petty officer rooms.		Narrowest Flood Opening
			mm ø	cm²
	a)	Open hull halve intake for cooling water pump starboard and port,		176.7
		Remove sea water filter	2 x 150	176.7
	b)	Open hull valve intake for cooling water pump for air compressor 3 and 4, remove sea water filter	40	12.5
	c)	Open hull valve for sea water intake for E-motor room cooling pump starboard, remove sea water filter	110	95.0
	d)	Open discharge to sea hull valve for E-motor room port	100	78.5
				539.4 cm²


Water depth in meters	10	20	30	40	50	60	70	80	90

Flooding time in minutes	21	17.7	15.8	15	14.2	11	10.3	9.6	9.2

These flooding times are longer than the longest, permissible staying time given in the previous chapter. As soon as the decreasing pressure difference allows, the diesel engine air induction trunk foot and head valve must be opened.

3.	Flooding the control room.		Narrowest Flood Opening
			mm ø	cm²
		Remove the filter of the auxiliary drain and trim pump	80	50.3
		Open intake from sea for the drain pump and for flooding regulating tanks
		Remove the filter of the main drain pump
		Open hull valve sea water intake for the drain pump and for flooding regulating tank
		Open drain pressure connection for main ballast tank 6 port	140	153.9
				204.2 cm²

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21	IX. Damage Control	U-boat Information


Water depth in meters	10	20	30	40	50	60	70	80	90

Flooding time in minutes	15.2	13.2	11.6	10	8.9	8.1	7.6	7.0	6.8

4.	Flooding the living room.
	The living room has no pressure hull openings. For escaping the boat move to the adjacent rooms or, in case they are fully flooded, flood the living room by opening the hatches in the pressure-proof bulkheads.

5.	Flooding the forward mine room.		Narrowest Flood Opening
			mm ø	cm²
		Open discharge to sea hull valve for auxiliary drain pump 2 and the sea water intake for flooding mine compensating tanks 5-8	100	78.5
		Remove WC check valve, open exterior cock group, open inner valve group	70	38.5
				117 cm²


Water depth in meters	10	20	30	40	50	60	70	80	90

Flooding time in minutes	32.5	27.5	24.7	21.2	19	17.2	16	14.8	14.3

6.	Flooding the conning tower.		Narrowest Flood Opening
			mm ø	cm²
		Conning tower flood valve (Conning tower air head valve)	100	78.5


Water depth in meters	10	20	30	40	50	60	70	80	90

Flooding time in minutes	2.9	2.4	2.1	1.9	1.7	1.5	1.4	1.3	1.3

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U-boat Information	IX. Damage Control	22

		7. Computation of flooding time.
		The time needed for flooding the pressurized compartment until pressure equalization at escaping hatch, is calculated from the following formula:

		L = air volume in the compartment about to flood in meters²
		F = cross-section of the flood opening in cm²
		= valve flow coefficient depending on the line type
		At depths below 4 meters it is equal to:
		for lines without valves = 0.6
		for lines with one valve only = 0.5
		for 2 lines connected by valves = 0.3
		= coefficient depending on the water pressure according to the diagram:

		It should be noted that at shallow depths, pressure is equalized before the water level reaches the lower edge of the air trap coaming. From that moment, special attention should be paid until the excess air leaks through the hatch and the water level rises up to the air trap coaming. The additional flooding time (after opening the hatch cover) is not included in the calculation. When the additional openings are opened (torpedo tubes, manholes), the boat can be abandoned in 1 minute or less.

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23	IX. Damage Control	U-boat Information

5)	Gas hazard.
		In the war zone the appearance of offensive warfare, explosive, combustion gases as well as smoke screens is to be expected. When gases enter the boat, the escape gear is to be used and the vessel is to be quickly rigged for dive except that the diesel engine air induction trunk is to be opened.
		After passing through the danger zone, all compartments are to be ventilated with air blowers and all corners and pockets are to be blown out with compressed air.

6)	Fire hazard.
		Fire sources inside the boat can be fought with portable fire extinguishers, at the upper deck also with the fire hose and nozzle from the deck wash line.
		The oxygen flasks, diesel engine starting air flasks and high pressure air banks are to be emptied in certain circumstances in case of large fire: oxygen flasks through the intake lines outboard, starting flasks through the diesel engines, high pressure air banks into the ballast tanks. Dry fire extinguishers are used to fight fires in the electric installation.
		Endangered main and auxiliary switchboards are shut down (disconnected by means of automatic battery circuit breakers). Endangered munitions magazines are to be flooded immediately.
		When the fire cannot be fought with available extinguishing equipment, the endangered compartment is to be abandoned and segregated (escape gear is to be taken).

7)	Fire extinguishing equipment and flooding installation.
	Fire extinguishing equipment see paragraph A VIII 1c
	Flooding installation see paragraph B III 5

8)	Drainage and compressed air systems.
	Drainage installation see paragraph A VIII 1e
	Compressed air systems see paragraph A III 4

U-Boat Type XB	B. Machinery Installations	Page 107

U-boat Information	I. Propulsion plant	1

B. Machinery Installations.

==================

Propulsion plant.

GW diesel engine installation.

General and performance figures.

Two diesel engines manufactured by GW are installed in the diesel engine room, they are single-acting, reversible, with solid (airless) injection, 9-cylinder, 4-stroke engines with direct injection and supercharging. Typical performance, revolution speed and fuel oil consumption for each engine are as follows:

1.)	Full load (safe endurance stress)
	~ 2100 HP with 470 RPM, ~ 188 grams/HP/hour
2.)	Overload (~ 3 hours)
	~ 2300 HP with 485 RPM, ~ 189 grams/HP/hour
3.)	Peak load (~ 30 minutes)
	over 240 HP with 492 RPM, ~ 190 grams/HP/hour

Construction of the propulsion plant.

Each shaft line is driven by one GW diesel engine. For further data about construction see section a) and c) and the propulsion plant operation manual.

Auxiliary machinery.

Supercharger.

Each engine can be supercharged by a positive displacement type charger, coupled by means of the step-up gear, driven by the engine. By this means, a greater amount of air ia achieved per cylinder and therefore a greater amount of fuel oil can be burned, which in turns leads to increased performance. The positive displacement charger built from 2 rotors (Roots type charger) rotates with a speed of over 2000 RPM at crankshaft rotation speed 470 RPM and is driven by means of the friction clutch manufactured by Bamag. Up to the 380 RPM the diesel engines run without, above – with supercharging.

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2	I. Propulsion plant	U-boat Information

	2.	Pumps.
		Each engine's fuel oil feed pump is installed on the control station side of the engine. It is a reversible, gear pump which feeds fuel under pressure to the fuel oil injection pumps of each cylinder.
		The cooling water for cooling the cylinder barrels and heads, for lubricating oil cooler and cooling the exhaust manifolds is fed by the coupled with each engine, reversible, rotary type, cooling water pump. It is installed at the front (control station) side and is driven by means of the step-up gear from the crankshaft of the engine. It feeds a sufficient amount of cooling water at engine revolution speeds over 120 RPM.
		The coupled lubricating oil pump of each engine is reversible, gear type pump, installed at the bottom, front (control station) side. It cools and lubricates all required engine parts. Lubricating oil pressure is controlled by the adjustable pressure-valve.

	3.	Governor. Receives lubricating oil from the diesel engine lubricating installation. For the GW diesel engine propulsion plant a dedicated pump is not provided.
		(further see B II 2)

	2)	Battery.
	a)	General and performance data.
		The battery consists of 248 cells manufactured primarily by the Akkumulatorenfabrik AFA in Hagen (type 33 MAL 800 W). Of the total number of 248, each 124 cells are gathered in the battery rooms 1 and 2. Individual cells in each battery room are connected in series, and so make up battery 1 and battery 2. Each battery output voltage is ~220 V. This is the primary voltage for the light and power circuits on the type XB boats. Another connection - so called "ground" - at the 62nd cell of each battery provides 110 V.
		Each battery is connected to the main switchboards by a 3-pole, automatic circuit breaker, which disconnects endangered battery when a short circuit or

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U-boat Information	I. Propulsion plant	3

		an impermissible current overload occurs. The 3rd pole of this breaker is triggered by small currents and secures the above mentioned "ground connection" when drawing current at half battery voltage.

	b)	Construction and maintenance.
		Each battery consists of cells enclosed in ebonite boxes, supported by porcelain insulators. In each box there are 33 positive and 34 negative plates. Plates of the same polarity are connected among each other by means of soldered terminal strips and thus create one plate set. For current collection, each strip has 5 terminals, which are passed through the box cover. Buses connecting the cells (leaded copper rails) are screwed onto the terminals. The lid of the cells is double-walled and has 3 openings:
		Extraction opening,
		Air entrance opening,
		Operation opening.
		The air entrance opening is designed in such a way that during a boat’s inclination up to 35° in any direction no acid is spilled from the cell.
		A grid of rubber tubes is installed over the cell boxes, from which connecting pipes lead to individual cells. The tube system is connected to the battery ventilating system and enables extraction of oxyhydrogen gas while charging the battery. The set of the vacuum-meters above the battery room show the under-pressure in the gas extraction system at 7 different points of the piping.
		Maintenance.
		Maintenance includes thorough cleaning the batteries from all metallic foreign bodies, oil, sea water and so on. The latter contains chlorine, which destroys the positive plates and leads to poisoning with chlorine gas. Inadequate battery ventilation can cause battery explosion (oxyhydrogen gas).
		The surface of the diluted sulphuric acid which fills the cells must cover the upper edges of the plates. Refilling can be done only with chemically clean water (distilled water).

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4	I. Propulsion plant	U-boat Information

Each month a battery check is to be performed. It includes checking acid density, acid level, temperature and voltage. Bilge water under the battery is examined (for the presence of the acid) from time to time to avoid the pitting of the pressure hull and battery mounts. Both battery bilges can be rinsed with the slaked lime and drained with the draining system. A dedicated measuring system for examining acid level during depth charge detonations is in development.

Capacity, discharging, final voltage.

A single cell 33 MAL 800 W at a temperature 30 degrees C has following performance values:


Discharge current	Duration	In so doing total extracted	Final Voltage in V
in Amps	in Hours	Amp Hours	Each cell	Each battery

3630	1-1/2	5450	1.63	202.12
2960	2	5920	1.67	207.00
2200	3	6600	1.71	212.04
1480	5	7400	1.75	217.00
838	10	8380	1.78	220.72
458	20	9160	1.80	223.20
196	50	9800	1.80	223.20

These values apply while discharging with so called constant current without interruptions up to the so called final voltage. Each battery partially regenerates during breaks in discharging, so in such cases total capacity is greater.

Charging.

Type 33 MAL 800 W charge begins with 1650 A (1st charging phase) until output voltage rises to 2.4 V per cell, 298 V per battery. Then current is reduced gradually at a constant voltage of 290 V to 415 A (3rd charging phase).

Further charging is performed with a constant current of 415 A up to the end of charging process. Charging with low current is also allowed, in such case

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U-boat Information	I. Propulsion plant	5

		the temperature can not exceed 45 degrees C.
		In special cases "fast charging” is done by doubling the current from the 1st charging phase, the charging time is shortened by about 1/3. Batteries must be adequately ventilated during charging and 30 minutes after by means of the battery ventilation fan.

	3)	Main switchboards (AEG rotary switchboards).
		Two – installed in the E motor room over the E motors, at starboard and port sides – main switchboards starboard and port are connected with each battery by means of the respective battery automatic circuit breaker.
		The main switchboards are identical and each consists of the "E motor – in series – or parallel – switch", 2 “Battery dividing switches” (for supplying 110 V) and one "drive direction switch". A "battery – in parallel – or series – switch" is not provided.
		The switchboard provides 3 basic switching configurations for the associated E motor:
		1. one half of the battery or 2 parallel connected halves of the batteries (110 V)
		both armatures of the E motor in series
		(low revolutions: dead slow)
		2. one battery or both batteries connected in parallel (220 V)
		Both armatures of the E motor in parallel
		(medium range of the revolutions: slow, half speed, 2x half speed)
		3. one battery or both battery connected in parallel (220 V)
		both armatures of the E motor in parallel
		(highest revolutions: 3/4 speed, emergency speed)

	4)	E-motor installation.
	a)	General and performance data.
		Both GU 720/8 – 287 type E motors are manufactured and provided by the AEG Berlin company.
		They are enclosed, fan cooled, direct current, shunt, with auxiliary series winding and commutating poles.
		The 8-pole motors are reversible.

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6	I. Propulsion plant	U-boat Information

		Cooling of each motor takes place by 2 blowers, installed behind the motor. Their driving motors are connected to the armature terminals so the load of the E motors develops the respective rotation speed of the blower. Cooling air is drawn from the E motor room and after leaving the E motors is cooled down in water-cooled air coolers.
		Each E motor develops the one-hour power of 550 HP (406 kW) at 300 RPM, 220 V, 2040 A, starting from the cold state. Continuous power is: 477 HP (344 kW) at 1720 A. Continuous output power of the generator is 610 kW at 350 V and 470 RPM.

	b)	Motor construction and connections.
		Each motor has the following main parts:
		1. Welded casing and bearing shields
		2. Magnet frame with poles and winding
		3. Shaft with 2 armatures, winding and commutator
		4. Brush supports and brush holders
		5. 2 bearings
		6. Terminals and connectors
		7. Shaft cooling installation.
		For step-by-step regulation of revolution speed, both armatures of the E motors can be connected either parallel or in series by means of the "E motor – in series – or parallel – switch". Revolution speed within the range between two steps (or the output voltage while operating in generator mode) can be achieved by means of weakening or strengthening the field.
		"Drive direction switch" enables switching the E motors "forward" and "backward".

	c)	Auxiliary machinery.
		The following auxiliary machinery is provided for operating the E motors:
		1. 2 electric fan blowers for each motor
		2. 2 x 2 air coolers (sea water cooled)
		3. Cooling water for the air cooler and E-motor bearings.

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U-boat Information	I. Propulsion plant	7

For 1.: The blowers are attached to the pressure hull, behind the main switchboards. They are connected with main switchboards.

For 2.: The E motor air cooler is located between E motors, under floor plating. In an emergency, the cooling water can be provided by the following pumps:

1. E motor room cooling pump

2. One of the cooling water pumps attached to the diesel engines

3. Auxiliary cooling water pump in the diesel engine room

4. Hand cooling water pump.

For 3.: Cooling of the E motor bearings usually takes place by means of the diesel engine cooling installation or by the cooling water pump in the E motor room.

The lubricating oil of the forward E motors bearings can be pumped through the small oil cooler for the further cooling by two small, electrically driven lubricating oil pumps starboard and port.

Shaft lines.

Propellers.

The 3-bladed propellers are made from bronze and in forward drive they turn top to outboard, that is, away from the boat. They are made from a single piece.

The propeller's dimens'ions:

Diameter	1750 mm
Pitch	1565 mm
Total area	1.35 meters²
Projected area	1.2 meters²
Material	Special casting brass grade B

Drive shafts, bearings and shaft brakes.

Both shaft lines consist of a propeller shaft and a thrust shaft. The latter connects with the E motor shaft and then with the diesel engine shaft.

The hollow shafts are made from Siemens' Martin-Stahl and rest in the forward and aft main thrust bearings, stern tube bearings and shaft strut bearings.

Outside the pressure hull, the shafts are coated with rubber and rapped with wire rope.

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8	I. Propulsion plant	U-boat Information

		Bronze bushings attached to the shafts as running surfaces. The shaft lines in the aft torpedo room are led through the pressure hull and are embedded in the stern tubes, foe which stuffing boxes are installed in bottom part of the spherical bulkhead at frame 13 ½. Shaft sleeves are installed as a pressure-proof cover enclosing shaft lines in the aft torpedo room, welded to the pressure hull, inside the torpedo compensating tanks and trimming tanks, up to the spherical bulkhead at frame 13 ½. The stern tubes are lined with the lignum vitae wood, as are the bearings of the shaft struts, in which the end of the shaft lines are supported, shortly before joining with the propellers. In the E motor room, near the flange couplings joining the propeller and thrust shafts, break drums with band breaks operated by means of jackscrews are installed on each line.

	c)	Main thrust bearing.
		The main thrust bearings are plate type and are located in the E motor room. They transfer the axial thrust of the propeller on to the pressure hull and are also used as support bearings. The thrust bearings have auto-lubrication and a built-in cooling installation.

	d)	Clutches.
		Between the diesel engines and E motors, as well as between the E motors and main thrust bearings, each shaft line is provided with double-cone, friction clutches, manufactured by the Bamag Company in Dessau.
		All 4 clutches are operated manually and by means of the compressed air.
		The nominal torque of the "main clutch" (between thrust bearing and E motor) is ~3200 mkg, the maximum operating torque (sliding torque) is ~7250 kgm +10%. The latter value for the "diesel engine clutch" is equal to 10500 mkg + 25%. This clutch is therefore larger than the main clutch.

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U-boat Information	I. Propulsion plant	9

	6)	Interaction of the engines and motors.
	a)	General.
		The propulsion plant on the U-Boat is divided into a surfaced cruise part (diesel engines) and a submerged cruise part (E motors). The E motors can be also used while cruising surfaced, i.e. while mooring, umooring, passing locks, and in all other situations, when the direction and revolution speed of the shafts must be change often and quickly.

	b)	Diesel engine only drive.
		In case of diesel engine only drive, the diesel engine clutch and main clutch of the shaft line must be engaged. Thus, there is power transmission from the diesel engine up to the propellers, and the rotors of the E motors are turning too. The armatures of the E motors are unpowered, they are running idle.

	c)	E motors only.
		In case of E motor only drive, the main clutches must be engaged, while the diesel engines clutches must be disengaged. The diesel engines are stopped, the E motors are running, powered from the batteries.

	d)	Support and buffer mode.
		Support mode is intended for special cases. The running configuration is the same as for the diesel engine only drive, but in addition the E motors are powered from the batteries. This configuration makes possible achieving greater speed during pursuits etc., omitting the matter of the material stresses.
		Buffer mode, while cruising with diesels on rough seas, prevents overspeeding the engines because of the propellers breaking above the surface. The configuration is the same as for the diesel only dive, with the addition of powered E motors. The voltage powering the motors is adjusted so that when the propellers are below the surface, the motors don't draw current or generate. When the propellers run over the surface, the increasing reduction of the load which causes increasing of the diesel engine

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10	I. Propulsion plant	U-boat Information

		RPM, is absorbed by E motor working as a generator. When the buffer mode is used, the battery must be ventilated.

	e)	Charging operation.
		The battery can be charged:
		in battery charging only mode,
		while cruising.
		In battery charging only mode the main clutches must be disengaged, the diesel engine clutches must be engaged and the diesel engines drive the E motors, which generate current charging the batteries. When charging while cruising, cruise speed can only be set in the range favorable for charging. Charging while cruising i.e."both diesel engines emergency speed forward" is not possible. When charging while cruising, the diesel engines drive the propellers and must deliver additional power for charging.

	f)	Diesel-electric drive.
		This mode is used in case of the damage or overhaul of one of the two diesel engines.
		Configuration: The driving side is set for diesel engine drive and current generation. The other shaft line is driven only by its E motor. The necessary power is generated by the E motor of the shaft line driven by diesel engine.
		War experience shows that, diesel-electric drive is by no means – though is still often taken as - economical driving mode, that is which makes possible setting a wide speed range. Instead, this is achieved by driving with only one shaft line in the diesel engine only configuration, while the other propeller is turning idle in the flowing water.

U-Boat Type XB	B. Machinery Installations	Page 117

U-boat Information	II. Auxiliary machinery for propulsion	1

II.

Auxiliary machinery for propulsion.

Ship's auxiliary machinery.

Main rudder and diving planes.

1. Main rudder.

Installation site	Stern torpedo room, deck
Quantity and type	1 E motor
Manufacturer	BBC


Voltage	220 V

Time	60 minutes	1 minute
Current draw	41.5 amps	61 amps
Demand	7.4 kW	10.6 kW
Rotational speed	770 RPM	680 RPM
Torque	9.35 mkg	15.2 mkg
Efficiency	81%	78.5%

2. Diving planes.

Installation site	Stern torpedo room, Bow room
Quantity and type	2 Imo-pressure oil motors
Manufacturer	Fried. Krupp GW, Kiel
Demand	Rotational moment at the drive shaft of 40 kg/cm² 1 hour rotational speed = 145 RPM = 28 mkg

Anchor and warping capstan installation.

1. Bow capstan.

Installation site	Forward mine room deck forward
Quantity and type	1 reversible compressed air motor with claw coupling
Power, Rotational speed	33 HP with 500 RPM
Working pressure	3.5 kg/cm²

2. Stern capstan.

Installation site	Upper deck, after ship, motor in stern room
Quantity and type	1 reversible compressed air motor with claw coupling
Power, Rotational speed	7 HP with 1000 RPM
Working pressure	3.5 kg/cm²

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2	II. Auxiliary machinery for propulsion	U-boat Information

Air compressor.

1. E compressor.

Installation site	E motor room
Quantity	2
Construction	Encapsulated, four-stage two cylinder piston compressor with pressure oiling, sea water cooling, oil pump, cooling pump, and compressed air cooling
Drive motor	Direct current shunt wound motor with commutating poles
Rated power Compressor 1:	At 220/340 V 32 HP, 128 Amp 550/650 RPM, 6.1 - 6.6 liters/minute, 205 kg/cm² high pressure
Compressor 2:	At 220/340 V 76 HP, 305 Amp 535/635 RPM, 14 liters/minute, 205 kg/cm² high pressure
Connections	High pressure distributor control room and high pressure air bank 1 and 2

2. Diesel air compressor.

Installation site	Diesel engine room forward
Quantity and type	2, crankless Junkers free piston compressor. Four-stage with pressure oiling, cooling pump and compressed air cooler.
Drive motor	Two-stroke diesel motor crankless with 2 opposed pistons (Junkers) with fuel oil pump
Performance	About 10 liters/minute at 205 kg/cm²
Piston oscillations	At 150 kg/cm² 810 strokes/minute
	At 205 kg/cm² 860 strokes/minute
Connections to high pressure installation
Exhaust piping	Both go to the diesel exhaust manifolds between the muffler and spark arrestor

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U-boat Information	II. Auxiliary machinery for propulsion	3

Auxiliary drain and trim pump.

Installation site	Control room aft
Quantity and type	1, electric via a worm gear drive two-cylinder double acting piston pump
Pumping performance	About 300 liters/minute against 105 meters
E motor rated power	13.2/15.5 kW = 15/19.5 HP at 220/340 V
Number of RPM (motor shaft)	1600/1920 RPM at 220/340 V
Power transmission	1 level worm gear drive
Connections	Drains from main and auxiliary drain line. Trim to forward and aft, discharge through the hull valve, to main ballast tank 6 port, to fire extinguishing installation and upper deck wash line and regulating tanks

Main drain and trim pump.

Installation site	Control room port aft
Quantity and type	1, electrically driven centrifugal pump with 1 impeller for low pressure and large cross section and 2 additional impellers connected in series for high pressure and small cross section
Switching I.)	Impeller 1, 2 and 3 in series
options II.)	Impeller 1 alone
	Impeller 2 and 3 idling
Pumping I.)	60 m³/hour at 104 meters WS
performance	40 m³/hour at 111 meters WS
	20 m³/hour at 116 meters WS
II.)	170 m³/hour at 8.8 meters WS
	125 m³/hour at 13.0 meters WS
	50 m³/hour at 16.3 meters WS
E motor rated power	At 220/340 V about 31/46 kW
Number of RPM (motor shaft)	2000/2300 RPM
Connections	Drains from main and auxiliary drain line, regulating tanks, mine compensating tanks 1-4, discharge to regulating tanks, mine compensating tanks, main ballast tank 6 and overboard.

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4	II. Auxiliary machinery for propulsion	U-boat Information

Auxiliary drain pump 1 and 2.

Installation site	Aft torpedo room port forward, forward mine room starboard aft
Quantity and type	2, electrically driven centrifugal pumps with 1 impeller (level 1) with large cross section for large outputs at low pressure and 3 additional impellers connected in series for low output at high pressure
Switching I.)	Impeller 1, 2, 3, and 4 in series
options II.)	Impeller 1 alone, impellers 2 and 3 and 4 idling. (output minimum volume of water, to avoid overheating)
Pumping I.)	35 m³/hour at 88 meters WS
performance	25 m³/hour at 108 meters WS
	14 m³/hour at 118 meters WS
	5 m³/hour at 123 meters WS
II.)	70 m³/hour at 8.3 meters WS
	50 m³/hour at 13.5 meters WS
	30 m³/hour at 15.5 meters WS
	10 m³/hour at 17.0 meters WS
E motor rated power	At 220/340 V - 17/26 kW
Number of RPM (motor shaft)	2600/3000 RPM
Connections	Main and auxiliary drain line

Intake and exhaust air fan.

Installation site	Forward side, diesel engine room deck
Quantity and type	2, centrifugal fan blowers
Ventilation performance	6000-6900 meters³/hour at ~ 30 mm WS, pressure head 340-450 mm WS
E motor rated power	At 220-340 V - 11.8/18 kW
Number of RPM (motor shaft)	2600/3000 RPM

Battery ventilation fan.

Installation site	Control room, starboard aft
Quantity and type	1, centrifugal ventilators
Ventilation performance	33 meters³/minute, pressure head 300 mm WS
E motor rated power	At 220-340 V ~ 5 HP
Number of RPM (motor shaft)	2600/3000 RPM

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U-boat Information	II. Auxiliary machinery for propulsion	5

Pressure oil pump.

Installation site	Control room starboard, middle to aft
Quantity and type	2 electrically driven pressure oil screw type pumps
Pertinent auxiliary equipment	4 pressure oil flasks each 300 liters capacity, 1 pressure oil collecting tank
Pressure range	45-80 kg/cm²
Capacity	each E-motor 48/70 kW at 220/340 Volts
Number of RPM	1600/2000 RPM

Periscope drive. (see also A VII, 2)

Installation site	Conning tower, or Control room for Control room periscope
Quantity and type	3 pressure oil motors to extend and retract and 1 Imo motor to rotate the fixed eye-level periscope.
Capacity	Conning tower periscope aft: ) each 6, 0/14, 0 PS at
	Conning tower periscope forward: ) 1500 RPM at
	Control room periscope: ) 48-80 kg/cm²
	Rotating motor for
	Control room periscope: 2.55 PS at 1700 RPM
Consumption	~ 47 liters/minute (extending motor)
	~ 35 liters/minute (rotating motor)

Refrigeration and deep freezing installation. (BBC Mannheim)

Refrigeration plants are installed to port in the galley, and to starboard in the forward part of the forward mine room. Additionally, deep freezing equipment is installed on the starboard side of the provisions locker (in the forward part of the living room) with a capacity of about 4 meters³.

The function of the refrigeration plant is to remove the heat which penetrates the cooling space and is absorbed by the refrigerated cargo.

The main parts are: cooling space, cooling installation, evaporator and automatic switching and control devices (for further details see description in volume 23, section 2).

Freon is used as the cooling agent.

Capacity = 650 changes per hour (at +40° C cooling air and at -10° C vaporization temperature)

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6	II. Auxiliary machinery for propulsion	U-boat Information

The electric motor is constructed for an operating voltage of 220/340 V.


Voltage	RPM	Rated power

220 V	1300	1.2 kW
340 V	1675	1.8 kW

Revolutions of the compressor at 220 V = 445 RPM

Revolutions of the compressor at 340 V = 579 RPM

Capacity of the cooling space = 1.05 meters³

The refrigeration plant stowage available in the forward mine room is removed from boats on which the deep freezing installation is provided.

Freon is used as the cooling agent.

Capacity = 3480 Kcal/day (at about +35° C cooling air and at about -20° C vaporization temperature)

The electric motor is constructed for an operating voltage of 220/340 V.


Voltage	RPM	Rated power

220 V	1400	1.3 kW
340 V	1850	2.1 kW

The capacity of the cooling space is about 3 meters³. Total weight 490 kg.

Air conditioning installation.

An additional cooling installation provided in the forward part of the diesel engine room, for which an evaporator is installed as a heat exchanger in the boat ventilation system. This so called ventilation air cooling installation cools down about 1/5th of the volume of air flowing through the room air fan. Simultaneously the cooled air has low humidity; that is, the air is dried.

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U-boat Information	II. Auxiliary machinery for propulsion	7

The heat exchanger is an aluminum air cooler (transverse fin evaporator with multiple coils) suspended from the ceiling of the diesel engine room and air can flow through for room ventilation and air circulation.

Type	Electrically driven two-cylinder compressor
Capacity	E-motor at 220/340 V 4.25 kW
	Evaporator: 1400 BTU at 30° C cooling air
Number of RPM	Motor 2380 RPM Compressor 580 RPM
Cooling agent	Freon (C Cl₂F₂)
Auxiliary machinery cooling pump

Distilling unit.

Installation site	E motor room, aft beneath the floor
Quantity and type	2, Siemens' and Halske Yype SP 2 gs III
Auxiliary equipment	Condenser, brine pump, vacuum pump, cooler, E heating element, filter, salt concentration meter, steam heating installation
Output performance	8.5 liters/hour freshwater each unit

The distilling unit can be heated electrically as well as by steam created by the steam generating installation located in diesel engine room.

Hand pumps.

1. Hand drain pump.

1 movable, double-piston, hand drain pump, with drain and discharge connections for hoses. Its performance is 6.25 meters³/hour at 80 strokes/minute against a small pressure-head.

2. Hand fresh water pump.

Type: hand vane pump. Performance: 30 liters/minute against 20 meter pressure-head and 104 strokes/minute, drain height: 7 meters.

3. Hand wash water pumps.

2 hand, vane pumps of performance 20 liters/minute by 104 strokes/minute and against a 20 meter pressure head each are located in the forward and aft WC. They are connected to all wash water tanks.

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8	II. Auxiliary machinery for propulsion	U-boat Information

4. Hand distilled water pump.

Quantity, type 1, vane pump

Performance 20 liters/minute at 104 strokes/minute

5. A hand distilled water pump for the heat condenser of the steam generating installation located in diesel engine room. Its performance is about 47 liters/minute, this is a vane type pump.

6. A hand sea water pump is located in the conning tower casing and is used for flushing the upper deck WC.

W.C. installation.

W.C.s with W.C. pumps are located in forward part of the aft torpedo room to starboard and in the aft part of the forward mine room to port. The 3rd W.C. is installed in the conning tower casing, at the upper deck. It is accessible through the trapdoor on the bridge.

Gyro compass installation. (see A VIII 3)

Circulating fan for air purification system.

For air circulation at silent speed (see A VIII 3b)

Auxiliary machinery for the diesel engine installation.

Auxiliary lubricating oil pumps port and starboard.

Installation site	Diesel engine room starboard and port forward
Quantity and type	2, screw type pumps with electric drive
Pumping capacity	60 meters³/hour at 55 meter pressure head
E motor rated power	at 220/340 V ~ 9.05 kW
Number of RPM	1680 RPM
Connections	Engine lubricating oil installation, suction also from lubricating oil supply tank

Hand lubricating oil pump.

A hand lubricating oil pump is installed in the diesel engine room forward to starboard. Its performance is 4.2 meters³/hour at 90 strokes/minute. It is connected to the starboard and port auxiliary lubricating oil pumps and discharges to the small lubricating oil consumption tank located to starboard at the forward diesel engine room bulkhead.

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U-boat Information	II. Auxiliary machinery for propulsion	9

Fuel oil feed pump.

The electrically driven fuel oil feed pump is located in the diesel engine room, forward to port. This screw-type pump is used for fuel oil intake and transfer. It is powered by 220-340 V, and at number of revolutions n = 1803/2130 RPM has a performance of 45/55 meters³/hour against a pressure head of 35 meters.

Hand dirty lubricating oil pump.

The hand dirty lubricating oil pump is installed in diesel engine room, at the bulkhead adjacent to the E motor room, to port. Its performance at 82 strokes/min is ~2.8 meters³/hour and it connects with the dirty lubricating oil tank and lubricating oil supply tanks port and starboard.

Auxiliary cooling water pump.

Installation site	Diesel engine room starboard and port forward
Quantity and type	1, electrically driven centrifugal pump
E motor rated power	at 220/340 V 8.1/12 kW
Pumping capacity	75/86 meters³/hour at 30/38 meter pressure head
Number of RPM	2900/3300 RPM
Connections	to the diesel engines, diesel air compressor and E motor room

Hand cooling water pump.

Installation site	Diesel engine room starboard forward over the hand lubricating oil pump
Quantity and type	1, piston hand pump

Lubricating oil purifier.

Installation site	Diesel engine room starboard forward
Quantity and type	1, oil centrifuge Type Mo C 515
Manufacturer	Rahmeschl and Schmidt A.G. Ölde in Westfalia
Number of RPM	Drive shaft 1420/1740 RPM
	Cylinder 9500/11600 RPM
Performance	0.5 meters³/hour

Auxiliary machinery for the E motors.

E motor fan blower.

Installation site	E motor room starboard and port behind the E motors
Quantity and type	4, shunt-wound motor with centrifugal fan

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10	II. Auxiliary machinery for propulsion	U-boat Information

Performance	each 4.06 kW, 55 meters³/hour
Number of RPM	2600/3000 RPM

E motor room cooling pump.

Installation site	E motor room starboard aft
Quantity and type	1, electrically driven, pressure resistant centrifugal pump
Pumping performance	50/72 meters³/hour at 20 meters pressure head
E motor rated power	at 220/340 V ~ 11.8 kW
Number of RPM	1200/1430 RPM

Bearing lubricating oil cooling installation for the E motors.

The small, electrically driven, bearing lubricating oil pump forces the oil lubricating the forward bearings of the E motor port and starboard through the oil cooler.

U-Boat Type XB	B. Machinery Installations	Page 127

U-boat Information	III. Draining and flooding	1

III.	Draining and flooding.
	The following are provided for draining bilges and tanks:
	1	Main drain pump
	2	Auxiliary drain pumps
	1	Auxiliary drain and trim pump
	1	Emergency drain pump
	and an auxiliary cooling water pump for draining the diesel engine bilge only.

	1)	Main drainage installation.
		The main drain pump, located in the control room, aft to port, drains from the main drainage line and therefore from the following rooms:
		Aft torpedo room
		E motor room
		Diesel engine room
		Battery room 1
		Control room
		Battery room 2
		Forward mine room
		Regulating tanks
		Moreover, the main drain pump can drain all auxiliary drainage lines.

	2)	Auxiliary drainage installation.
		Auxiliary drain pumps 1 and 2, located in the aft torpedo room and forward mine room drain from the main drainage line as in paragraph 1) main draining installation. Auxiliary drain pump 1 in the aft torpedo room drains from the auxiliary drainage line from the following rooms, tanks etc:
		Aft torpedo room
		Torpedo compensating tanks 1 and 2
		Emergency drain connection aft
		Waste water tank 1
		Brine tank
		E motor room
		Diesel engine room aft
		Emergency drain connection in the diesel engine room
		Waste water tank 2
		Battery room 1

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2	III. Draining and flooding	U-boat Information

		Auxiliary drain pump 2 in the forward mine room drains through the auxiliary drainage line from the following rooms, tanks etc:
		Waste water tank 3
		Battery room 2
		Living space aft
		Waste water tank 4
		Forward mine room
		Mine compensation tanks 5-8
		Emergency drain connection forward
		The auxiliary drain and trim pump drains through the main drainage line as in the paragraph 1) Main draining installation and from the auxiliary drainage line from the following rooms, tanks etc:
		Emergency drain connection in petty officers room
		Mine compensation tanks 1-4
		Control room
		Munitions magazine
		Listening room
		Conning tower periscope shaft
		Provisions storage
		Emergency drain connection control room

	3)	Hand drainage installation.
		Each boat is provided with an emergency drain pump. It has drain and discharge connections and can drain from all bilges.

	4)	Artificial flooding installation.
		Not available.

	5)	Natural flooding installation.
		The following tanks can be naturally flooded:
		1. Torpedo compensating tank 1 and 2
		2. Regulating tanks 1 and 2 starboard and port
		3. Mine compensating tanks 1-4
		4. Negative buoyancy tanks
		5. Mine compensating tanks 5-8
		The munitions magazine cannot be flooded.

U-Boat Type XB	B. Machinery Installations	Page 129

U-boat Information	III. Draining and flooding	3

		For 1: The torpedo compensating tanks are located in the aft torpedo room. They are flooded through the hull valve on the port side and intermediate valve related to each tank. Draining takes place by means of any drain pump.

		For 2: The regulating tanks are located at both sides of the control room, outside the pressure hull. They are flooded:
		1. Through the hull valve of the main drain pump
		2. Through fine flooding valve via the water flow meter
		Draining takes place by means of compressed air or any drain pump.

		For 3: Mine compensating tanks 1-4 are located outside the pressure hull, at the level of the control room. They are flooded through the hull valve of the main drain pump and the water flow meter. They are drained by means of compressed air, auxiliary drain and trim pump and flooding line of the main drain pump.

		For 4: The negative tanks are located outside the pressure hull at the level of the control room. They are flooded through their own hull valve in the control room. They are drained by means of compressed air.

		For 5: Mine compensating tanks 5-8 are located in the forward mine room. They are flooded through their own hull valve on the starboard side of the room. They are drained by means of any drain pump.

Page 130	B. Machinery Installations	U-Boat Type XB

1	IV. Sea, wash, and fresh water installations	U-boat Information

IV.

Sea, wash, and fresh water installations.

Sea water installation.

The warm sea wash water installation is part of the sea water installation. The line branches from the cooling water head tank and leads through the hull valve to the wash basins and galley wash sink. One more line leads through the valve to the shower head on the upper deck. The shower head is connected with the deck wash line by means of a three-way cock. Both W.C.s are flushed by means of the hand-operated flush pump located in each W.C.

The sea water extinguishing installation is located in the control room. It branches from the valve box of the auxiliary drain and trim pump discharge line. At the upper deck the line extends between frames 35 – 72 on the starboard side and between frames 72 – 118 on the port side. The line is provided with three hose connections (at frame 35 starboard, at frame 70 port, at frame 118 in the conning tower casing).

Wash water installation.

2 tanks and 1 wash water daily supply tank are provided.

Wash water tank 1 in forward living space to port	- 850 liters
Wash water tank 2 in the forward mine room port	- 610 liters
Wash water daily supply tank in the petty officers room	- 60 liters
	1520 liters

Additionally, torpedo compensating tanks 1 and 2 in aft torpedo room with a total capacity of 7.160 meters³ can be used as wash water tanks.

The hand wash water pump, located in the aft torpedo room, drains from the torpedo compensating tanks. The hand fresh water pump located in the petty officers room, can drain from wash water tank 1 and 2 and discharge to the wash water daily supply tank. The hand wash water pump in the forward mine room also drains from both wash water tanks and discharges to the washbasins. Filling of wash water tanks 1 and 2 takes place from the upper deck through the fresh water line.

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U-boat Information	IV. Sea, wash, and fresh water installations	2

Filling of the torpedo compensating tanks is done by connecting hoses to the sounding lines.

Fresh water installation.

Four tanks are provided, whose contents can also be used as wash water.

Fresh water tank 1 petty officers room	- 780 liters
Fresh water tank 2 control room	- 230 liters
Fresh water tank 3 forward living space starboard	- 2000 liters
Fresh water tank 4 forward living space port	- 2000 liters
	5010 liters

One hand fresh water pump is installed in the galley as the part of the fresh water installation. It drains from any of 4 tanks and can discharge water to the galley sink and washbasins. The pump can also be used for water intake.

Waste water installation.

4 waste water tanks are provided.

Waste water tank 1, in the aft torpedo room, collects waste water from the washbasin in the aft W.C.

Waste water tank 2, in the petty officers room, collects waste water from the petty officers room washbasin and galley sink.

Waste water tank 3, in the living room forward, collects waste water from the commanding officer's and chief petty officers' wash basins.

Waste water tank 4, in the forward mine room, collects waste water from the wash basin in the forward W.C.

All waste water tanks can be drained by means of the auxiliary drainage lines.

Page 132	B. Machinery Installations	U-Boat Type XB

1	V. Ventilating installations	U-boat Information

Ventilating systems.

Boat ventilation.

The boat is provided with intake and exhaust air fans. The intake duct is located on the starboard side, the exhaust duct is on the port side of the boat. Both fans are installed in the diesel engine room. From each fan an air trunk runs outboard, up to the aft part of the conning tower casing. The air trunks are closed by means of a head and a foot valve.

The air intake duct has the following connections:

Aft torpedo room	1 x intake
E motor room	2 x intake air
Diesel engine room	1 x intake air
Petty officers room	2 x intake air
Control room	2 x intake air
Conning tower	1 x intake air
Living space forward
Radio room	1 x intake air
Provisions room	1 x intake air
Listening room	1 x intake air
Officers room	1 x intake air
Chief petty officers room	1 x intake air
Mens room	1 x intake air
Lower mens' room	1 x supply air
Forward mine room	1 x intake air

The air exhaust duct has the following connections:

Aft torpedo room	2 x exhaust air
WC aft	1 x exhaust air
Charging locker for hand lamps	1 x exhaust air
Charging case for Eto test gear	1 x exhaust air
Eto vacuum gauge	1 x exhaust air
E motor room	3 x exhaust air
Diesel engine room	3 x exhaust air
Petty officers room
Wash and drying room	1 x exhaust air
Galley	1 x exhaust air
Provisions locker	1 x exhaust air
Battery automatic switch room 1	1 x exhaust air

U-Boat Type XB	B. Machinery Installations	Page 133

U-boat Information	V. Ventilating installation	2

Petty officers room	1 x exhaust air
Control room	2 x exhaust air
Conning tower periscope shaft	1 x exhaust air
Munitions magazine	1 x exhaust air
Active sonar room	1 x exhaust air
Control room	2 x exhaust air
Living space forward
Radio room	1 x exhaust air
Battery automatic switch room 2	1 x exhaust air
Provisions room	1 x exhaust air
Listening room	1 x exhaust air
Commanders room	1 x exhaust air
Officers room	1 x exhaust air
Chief petty officers room	1 x exhaust air
Mens room upper	1 x exhaust air
Mens room lower	1 x exhaust air
Forward mine room
WC forward	1 x exhaust air
Forward mine room	2 x exhaust air

The ventilating system can be used with or without air the conditioning installation in 12 configurations (see operation plan 20 and 21).

Battery ventilation.

To remove oxyhydrogen gas a battery ventilation fan is provided in the control room. Both batteries have one common exhaust duct, which can be connected with the battery ventilation fan and with the exhaust air fan.

The battery exhaust duct can be isolated from each battery by a flap and a valve. Below the valves the ducts run to each battery and go beneath the deck plating of the rooms located above. They are used as natural ventilation when battery ventilation is stopped.

Page 134	B. Machinery Installations	U-Boat Type XB

3	V. Ventilating instillation	U-boat Information

		The vacuum resulting from battery ventilation is shown by the under-pressure gauges and for the cell 33 MAL 800 W is 16 mm of pressure head.
		The vacuum gauge for battery 1 is located in the petty officers room
		The vacuum gauge for battery 2 is located in the living room forward
		The battery ventilation system can be used in 3 configurations (see operation plan 22).

	3).	Additional ventilation for air purification while running at silent speed.
		See A VIII 3 b.

U-Boat Type XB	B. Machinery Installations	Page 135

U-boat Information	VI. Heating installation	1

VI.

Heating installation.

A steam and electric heating installation is provided.

Steam heating.

The steam heating system has connections for flexible hoses on the upper deck, over the diesel engine room, on the starboard and port sides for steam intake and exhaust.

The steam lines run throughout the boat from the forward mine room to the aft torpedo room and are connected to radiators located as follows:


Room	Number	Location

Aft torpedo room	5	1 and 2 starboard and port aft
		3 WC aft
		4 port forward
		5 centerline forward
E motor room	4	1 and 2 starboard and port amidships
		3 and 4 starboard and port forward
Diesel engine room	4	1 and 2 starboard and port amidships
		3 and 4 starboard and port center
Petty officers room	3	1 wash and drying room
		2 and 3 centerline forward
Control room	4	1 centerline aft
		2 conning tower
		3 centerline center
		4 centerline forward
Living space	7	1 centerline aft
		1 radio room 2 port aft
		3 officers room centerline
		4 and 5 chief petty officers room centerline
		6 mens' room upper
		7 mens' room lower
Forward mine room	7	1 centerline aft
		2 WC forward
		3 and 4 starboard center
		5 centerline center
		6 and 7 starboard and port forward

Page 136	B. Machinery Installations	U-Boat Type XB

2	VI. Heating installation	U-boat Information

Electric heating.

Each boat is equipped with 11 portable electric heaters. Each heater is provided with a long connecting cable with a plug and can be connected to the electric power installation in the following compartments by means of sockets:


Room	Number	Location

Aft torpedo room	2	1 starboard aft, 2 port forward
E motor room	1	starboard forward
Diesel engine room	2	1 and 2 port forward
Petty officers room	3	1 and 2 port forward, 3 port aft
Control room	2	1 starboard center, 2 conning tower
Living space forward	7	1 mens' room upper, 1 mens' wardroom lower, 1 chief petty officers room, 1 officers room, 1 commanders room, 1 sound room, 1 radio room
Forward mine room	2	starboard forward, 2 port aft

Steam generating installation.

The boat is equipped with a steam generating installation.

Principle of operation:

The diesel engine exhaust gas lines are surrounded by a coil heater. The circulating pump forces fresh water through the coil under a pressure of 3 kg/cm². The water reaches a temperature of about 130 degrees C. Then the water is forced through the orifice plate on reaching the steam generator.

After passing the orifice plate the water loses pressure. The thermal capacity is too large for the new, lower pressure and part of water evaporates. The steam generator separates the water and steam. The water is drained by the circulating pump, the steam is led to the common steam heating line and then flows to the heaters. Condensed steam is forced through the condensate cooler and gives up a considerable amount of heat to the cooling water. From the condensate cooler the condensed steam flows to the condensate steam collecting tank. From tank the feed pump forces it through the regulating valve to the evaporator and so completes the heating cycle.

U-Boat Type XB	B. Machinery Installations	Page 137

U-boat Information	VII. Lubricating oil installation	1

VII.

Lubricating oil installation.

The lubricating oil installation lubricates all running and sliding parts of the diesel engines and cools the needles of the fuel oil valves.

The amount of lubricating oil stored on the board is 20080 liters.

It is stored as follows:

Lubricating oil collecting tank starboard (diesel engine room)	1360 liters
Lubricating oil collecting tank port (diesel engine room)	1360 liters
Lubricating oil supply tank 1 (petty officers room starboard aft)	4000 liters
Lubricating oil supply tank 2 (petty officers room port aft)	4000 liters
Lubricating oil supply tank 3 (petty officers room starboard forward)	4000 liters
Lubricating oil supply tank 4 (petty officers room starboard forward)	4000 liters
Dirty lubricating oil tank (diesel engine room)	_1360 liters
	20080 liters

Each diesel engine in normal operating conditions has its own close-cycled lubricating oil installation. That means that the gear pump coupled with each engine drains the oil from the associated collecting tank and forces it through the oil cooler to all lubricating and cooling points. Then, the oil collects in the diesel engine's crankcase and flows back to the lubricating oil collecting tank.

At the highest rotation speed of diesel engine the coupled lubricating oil pump achieves a performance 500 liters/minute. The close-cycled installation of each engine can be connected together after the oil coolers.

The auxiliary lubricating oil pumps make it possible to lubricate the engines before running them, as well as cooling them after stopping. They can substitute for the main pumps and can also be used for lubricating oil intake and discharge. The auxiliary lubricating oil pumps are electrically driven, screw type pumps and each has a performance of 700 liters/minute. In addition there is also hand lubricating oil pump.

The lubricating oil in supply tanks 1-4 can be moved to the collecting tanks by means of the auxiliary lubricating pumps.

The lubricating oil intake takes place through the intake connection on the upper deck, port, either by means of the auxiliary lubricating oil pump or by filling from barrels through two valve boxes located in the diesel engine room, forward, to the lubricating oil supply or collecting tanks.

Page 138	B. Machinery Installations	U-Boat Type XB

2	VII. Lubricating oil installation	U-boat Information

	2)	Lubricating oil purification installation.
		The lubricating oil purification installation purifies the dirty lubricating oil of foreign bodies.
		Dirty oil is pumped by the dirty lubricating oil pump from the collecting or dirty oil tanks through the electric or steam pre-heater. In the drum-type purifier the lubricating oil is separated into pure oil, water, mud and solid contaminants. The purified oil is pumped back by the purified oil pump to the respective tank. The waste water discharges to the bilge.

U-Boat Type XB	B. Machinery Installations	Page 139

U-boat Information	VIII. Fuel oil installation	1

VIII.

Fuel oil installation.

1).

Fuel oil installation.

Fuel oil is stored in two fuel oil tanks located outside, on both sides of the pressure hull. Additionally, 4 main ballast and reserve fuel oil tanks located on the starboard and port sides can be used as fuel oil tanks.

They are located as follows:

Main ballast and reserve fuel oil tank 2 at the level of the aft torpedo room	(A frame 8-24)	43.25 m³
Main ballast and reserve fuel oil tank 3 at the level of the E motor room	(A frame 24-34)	58.20 m³
Main ballast and reserve fuel oil tank 8 at the level of the living space, forward mine room	(A frame 99-109)	69.05 m³
Main ballast and reserve fuel oil tank 9 at the level of the forward mine room	(A frame 109-128)	67.55 m³
Fuel oil tank 1a at the level of the diesel engine room	(A frame 34-43	83.30 m³
Fuel oil tank 2a at the level of the forward living space	(A frame 93-99)	54.90 m³

The main ballast and reserve fuel oil tanks are accessible from the upper deck through man holes, which are located as follows.

Main ballast and reserve fuel oil tank 2 between A frame 19 and 20 on port side and between A frame 21 and 22 on the starboard side

Main ballast and reserve fuel oil tank 3 between A frame 33 and 34 on both sides

Main ballast and reserve fuel oil tank 8 between A frame 99 and 100 on both sides

Main ballast and reserve fuel oil tank 9 between A frame 111 and 112 on both sides.

In the main ballast and reserve fuel oil tanks oil floats above the water. Inside the tanks there are connecting lines to the fuel oil delivery lines and, at the upper deck, connecting lines to the fuel oil compensating line. Moreover, each side of the main ballast and reserve fuel oil tanks have a vent line to the inside of the pressure hull and test lines at the upper deck.

Fuel oil tanks are equipped exactly the same as the main ballast and reserve fuel oil tanks. Their man holes are located on the upper deck, on both sides, between the outer shell frames:

Fuel oil tank 1a 42 and 43,

Fuel oil tank 2a 93 and 94.

Each side of the fuel oil tank has a test line on the upper deck and combined sounding, vent and drain lines led to the inside of the pressure hull.

Page 140	B. Machinery Installations	U-Boat Type XB

2	VIII. Fuel oil installation	U-boat Information

		Fuel oil is fed under static pressure in the fuel oil compensating line through the fuel oil delivery valve group, control valve boxes and filter to the fuel oil gravity tank. From there, fuel oil flows to the fuel oil feed pumps and to both diesel compressors.

	2)	Fuel oil transfer installation.
		Fuel oil transfer and delivery takes place by means of the fuel oil transfer pump through the aft intake connection. Fuel oil transfer through the forward intake connection takes place by means of outside fuel oil transfer pump. The fuel oil flows under pressure through the forward intake connection, fuel oil meter to the fuel oil transfer line through the following installation parts:
		a) Forward fuel oil transfer hull valve
		b) Selector valve, fuel oil transfer meter forward
		c) Discharge fuel oil transfer meter.
		When filling the tanks, the respective vent valves must be opened.

U-Boat Type XB	B. Machinery Installations	Page 141

U-boat Information	IX. E installation	1

IX.	E installation.
	1)	E Motors.
		See B I 4.

	2)	Batteries.
		See B I 2.

	3)	Main switchboards.
		See B I 3.

	4)	Auxiliary switchboards and power distribution.
		The following auxiliary switchboards are in the boat:
		a) Auxiliary switchboard 1 (aft torpedo room starboard)
		b) Auxiliary switchboard 2 (E motor room starboard)
		c) Auxiliary switchboard 2a (E motor room port)
		d) Auxiliary switchboard 3 (control room starboard)

		For a) Auxiliary switchboard 1, in addition to powering light group 7, supplies the power for the Eto charging units as well as the charging locker for hand lamp batteries. Contrary to the other switchboards, auxiliary switchboard 1 is powered by half of the battery voltage: 110 – 170 V.

		For b) Auxiliary switchboard 2, as for the other switchboards, provides the electricity for the boat's main power and light installations. It is located above the main switchboard starboard. Voltage for the regulated and unregulated parts of installations is taken through the voltage switch from the main switchboard port and battery 1. The auxiliary switchboard is powered by full battery voltage: 220 – 340 V.

		For c) Auxiliary switchboard 2a powers the radio switchboard located in the listening room. The automatic voltage regulator is set at 220 V. The switchboard is embedded into main switchboard port. It is powered through the voltage switch from the auxiliary switchboard 2 power section and auxiliary switchboard 3 power section.

		For d) Auxiliary switchboard 3 (light section) is located in the control room. It is used for powering the light circuits, the TDC, torpedo fire control and gyro compass installations. The voltage regulator is set at the 220 +/- 6 V. The auxiliary switchboard 3 (power section) is located in the control room near the auxiliary switchboard 3 (light section) and supplies electricity for the power installation.

Page 142	B. Machinery Installations	U-Boat Type XB

2	IX. E installation	U-boat Information

Unregulated voltage in the range 220 – 340 V is branched and delivered without any further adjustments.

Electric equipment

E drive motors and their current draw.

1.	Pumps (see B II 1-2)
	Main rudder motor
	Number	1
	Installation site	Aft torpedo room
	Manufacturer	B.B.C. Mannheim
	Construction	GS 11b direct current, compound motor
	Rated power	7.4 kW for 60 minutes, 10.6 kW for 1 minutes
	Voltage	220 V
	Number of RPM	770 RPM for 1 minute
		680 RPM for 60 minutes

Rotary converters and associated equipment.

Gyro compass converter.

Powers the gyro compass at the necessary voltages and current rates.

It produces:

12 V 3 phase alternating current for powering the gyroscope motor in the gyro compass installation,

55 V 1 phase alternating current for powering the transmitter (passing the heading to the repeaters)

220 V direct current for the amplifier.

Medium frequency generator:

	Construction	A 220 T
	Rated power	0.5 kVA
	Voltage	120 V
	Current	2.4 A
	Phase shift	cos φ = 0.7
	Number of RPM	3330 RPM
	Frequency	333 Hz

Single phase current generator:

	Construction	A 220 T
	Rated power	0.86 kVA
	Voltage	50 V

U-Boat Type XB	B. Machinery Installations	Page 143

U-boat Information	IX. E installation	3

	Phase shift	cos φ = 0.5
	Number of RPM	3330 RPM
	Frequency	55.5 Hz

Direct current driving motor:

	Construction	A 220 T
	Voltage	220 V
	Current	9.5 A
	Number of RPM	3330 RPM

Communications equipment converter.

The alternating current required by the electronic communication equipment is provided by 4 converters with output power of 6; 1.5; 0.3; and 1.2 kVA. The 6; 1.5 and 0.3 kVA converters can be used interchangeably, while the 1.2 kVA converter is necessary for the transmitters (high frequency). All converters are installed in the E motor room.

a)	6 kVA converter:
	Construction	GW 13/200 +EGW 13/200
	Rated power	6 kVA
	Voltage	110 V
	Current	27.2 A
	Phase shift	cos φ = 0.8
	Number of RPM	1500 RPM
	Frequency	50

b)	1.5 kVA converter
	Construction	ENG 34/4 T
	Rated power	1.5 kVA
	Voltage	225 V
	Current	6.7 A
	Phase shift	cos φ = 0.8
	Number of RPM	1500 RPM
	Frequency	50

Page 144	B. Machinery Installations	U-Boat Type XB

4	IX. E installation	U-boat Information

c)	0.3 kVA converter:
	Construction	GW 7/125 +EGW 7/125
	Rated power	0.3 kVA
	Voltage	110 V
	Current	5 A
	Phase shift	cos φ = 0.8
	Number of RPM	1500 RPM
	Frequency	50

d)	1.5 kVA converter
	Construction	FGH 25T
	Rated power	0.12/0.45 kVA
	Voltage	400/1500 and 280 V
	Current	0.3/0.3 A
	Phase shift	cos φ = 0.9
	Number of RPM	2500 RPM
	Frequency	1500

UT converter.

The UT converter, which generates the required AC voltage for the underwater telegraphy installation, is located in the E motor room.

	Construction	EHG 0/15 B
	Rated power	2 x 200 Watts
	Voltage	60 V
	Current	4.2 A
	Phase shift	cos φ = 0.9
	Number of RPM	5150 RPM
	Frequency	2060

Depth sounding converter.

Provides the necessary voltage for the depth sounding device and is located in the E motor room.

	Construction	EHG 25T
	Rated power	0.7 kVA
	Voltage	100 V
	Phase shift	cos φ = 0.9
	Number of RPM	2500 RPM
	Frequency	1500

U-Boat Type XB	B. Machinery Installations	Page 145

U-boat Information	IX. E installation	5

Torpedo converter.

a)	Eto charging converter.
	The generator:
	Construction	V G 46a 6-4
	Current	KB 35 A; D B 20 A
	Voltage	+ 30 V/ - 40 V/ - 10 V
	Number of RPM	1500/2600 RPM
	Frequency	2060

	Driving motor:
	Construction	V G 37a
	Current	5 A
	Voltage	110-150 V D B; 170 VKB
	Number of RPM	1500/2600 RPM

b)	Rotary amplifier for the gyro angle setting gear
	Generator:
	Construction	VG 5.5; 4a 5
	Voltage	130 V
	Current	3 A
	Rated power	0.93 kW
	Number of RPM	2000 RPM

	Driving motor:
	Construction	VG 5.5; 4a 5
	Voltage	220 V
	Current	3.2 A
	Rated power	0.5 kW
	Number of RPM	2000 RPM

	Generator:
	Construction	VC 3
	Voltage	55 V
	Current	3 A
	Number of RPM	2000 RPM

Page 146	B. Machinery Installations	U-Boat Type XB

6	IX. E installation	U-boat Information

Ordering and reporting installations.

General information and power supply.

Ordering and reporting group 1b in the control room powers the following installations:

Engine order telegraph port and starboard

Rudder order telegraph and rudder angle indicator system

Alarm bell and flashing light system

Log installation.

Ordering and reporting group 1a in the control room powers the following installations:

Compartment ready indicating system

Hull closure indicating system

Vent valve indicating system

Shaft mine launching reporting installation.

Engine order telegraph system.

The whole installation consists of the port and starboard system.

Each system is built from:

1.	Transmitter and receiver in conning tower (control room repeater)
2.	Transmitter and receiver in control room
3.	Transmitter and receiver in E motor room with indicating lamp and bell
4.	Transmitter and receiver in diesel engine room with flashing lamp and bell

Additionally, there are switching boxes in the conning tower and in the control room, a powering box in the control room and a flashing lamp control box in the diesel engine room.

The installation is powered by 220 V DC from ordering and reporting group 1b in the control room.

The power lines of the port and starboard systems are fused in the powering box.

Receivers in the following rooms can be connected by means of switching boxes associated with the respective transmitters in the control room and conning tower:

In switch position I: diesel engine room

In switch position II: diesel engine room and E motor room

In switch position III: E motor room

U-Boat Type XB	B. Machinery Installations	Page 147

U-boat Information	IX. E installation	7

		During silent running, only the receivers in the E motor room are connected. In this case the acoustic indicators (horns and bells) are disconnected by means of the control switch in the powering box and the indicating lamp is connected.

	3.	Shaft revolution indicator system.
		The system makes possible reading and watching the revolution speed of the main shafts at stations remote from the machine sites. Each shaft has an associated indicating system, which consists of the transmitter in the E motor room and the receivers in the following rooms:
		1. E motor room
		2. Diesel engine room
		3. Control room
		4. Listening room
		5. Conning tower.
		Additionally, for the port and starboard system individual distribution boxes in the control room are provided, at which each receiver can be independently disconnected. Illumination of the conning tower receiver takes place through the dedicated circuit powered from light group 5a.

	4.	Rudder order telegraph and rudder angle indicator system.
		Rudder order telegraph is used to pass rudder orders between the control room and the aft torpedo room.
		The rudder angle indicator system is used to indicate the present rudder position at the command stations and in the diesel engine and E motor rooms.
		It consists of:
		1 Rudder order telegraph receiver with built in rudder angle receiver in aft torpedo room
		1 Rudder angle transmitter in aft torpedo room
		1 Rudder angle receiver in E motor room
		1 Rudder angle receiver in diesel engine room
		1 Rudder angle receiver in listening room
		1 Rudder angle receiver with interior lighting in conning tower

Page 148	B. Machinery Installations	U-Boat Type XB

8	IX. E installation	U-boat Information

		1 Rudder angle receiver with interior lighting for the bridge.
		Operating voltage 220 V is supplied from ordering and reporting group 1b in the control room.
		When the installation is in operation, the red "out of service" marks at all receivers should be not visible.

	5.	Diving planes angle indicator system.
		The diving planes angle indicator system is used to show the present position of the diving planes in the control room and in the conning tower.
		It consists of:
		1 Rudder angle transmitter on the aft dive plane
		1 Rudder angle transmitter on the forward dive plane
		1 double receiver for forward and aft dive planes in the conning tower
		1 Rudder angle receiver for the forward dive plane in the control room
		1 Rudder angle receiver for the aft dive plane in the control room.
		The system is powered by 220 V through the 2-pole switch from ordering and reporting group 1b in the control room.
		"Out of service" marks are used in the same manner as in the rudder order telegraph and rudder angle indicator system.

	6.	Alarm bell and flashing light system.
		The system is used for giving alarm signals. It is powered by 220 V DC from ordering and reporting group 1b in the control room.
		Transmitters (AC) are located in the conning tower and in the control room.
		They are connected with the alarm bells located in:
		Aft torpedo room,
		E motor room,
		Diesel engine room,
		Petty Officers room,
		Control room,
		Living room forward,
		Forward mine room.

U-Boat Type XB	B. Machinery Installations	Page 149

U-boat Information	IX. E installation	9

		In the noisy environment of the diesel engine room part of the room lamps are flashed.

	7.	Compartment ready indicating system.
		The compartment ready indicating system makes possible fast reporting of the readiness of each room to the control room. It is powered through the power switch in the switch and fuse box of ordering and reporting group 1a. Ready reporting switches are installed in the following rooms so that readiness can be reported to the control room:
		Aft torpedo room
		E motor room
		Diesel engine room
		Petty Officers room
		Living room forward
		Forward mine room.
		Readiness reporting takes place by switching the ready reporting switch of the relevant room. In the control room the corresponding lamp in the indicator box starboard lights up. The lamp lights under the white view glass with the word "ready" on it. The names of the rooms are above the view glass.

	8.	Hull closure indicating system.
		The hull closure indicating system indicates the state of closure of the most important hull openings while diving by means of a dedicated indicator box in the control room starboard. The reporting system is powered from the switch and fuse box of the signal circuit. The reporting switches are mechanically coupled with the 8 most important hull closures and the closed state of the hull opening switches the indicating lamp on.
		The indicating lamps lights "bright" in the closed state and remains bright during the dive.
		When the hull closures are opened, the relevant lamps light "dim".

Page 150	B. Machinery Installations	U-Boat Type XB

10	IX. E installation	U-boat Information

		The following hull closures are coupled with the system:
		1. Inner exhaust gas valve starboard
		2. Inner exhaust gas valve port
		3. Diesel air intake head valve starboard
		4. Diesel air intake head valve port
		5. Ventilation air intake head valve
		6. Ventilation air exhaust head valve
		7. Outer exhaust gas valve starboard
		8. Outer exhaust gas valve port
		9. Water tight stern.
		While for the closures 1 – 8 the indicating lamps light "bright" when the closure is closed, the indicating lamp for the watertight stern lights "bright", when the closure is opened.

	9.	Vent valve indicating system.
		The vent valve indicating system shows in the control room, if the vent valves are opened and when compressed air is supplied to the vent valve operating pistons.
		In the control room an indicating box with 12 lamps and 3 push buttons is provided.
		When the vent valves are opened, the indicating lamp lights "bright".
		When the vent valves are closed, the indicating lamp lights "dim".
		The following vent valve chambers are coupled with the vent valve indicating system.
		1. Main ballast tank 1
		2. Main ballast and reserve fuel oil tank 2 and 3
		3. Main ballast tank 4 and main ballast tank 5
		4. Main ballast tank 6 and 7
		5. Main ballast and reserve fuel oil tank 8 and 9
		6. Main ballast tank 10.
		The vent valve indicating system is powered through the switch and fuse box from the signal circuit, which in turn is connected to ordering and reporting group 1a, and which has its own main switch there.

U-Boat Type XB	B. Machinery Installations	Page 151

U-boat Information	IX. E installation	11

		When the low pressure air control cocks are out of order, there is no compressed air or any other reason occurs, the corresponding station can be commanded "open" by means of the push button. The command "open" is shown by means of a red indicating lamp.

	10.	Torpedo fire control and orders indicator system.
		The torpedo fire control system is used to pass all necessary commands and shooting values to the stations at the torpedo tubes during the torpedo attack. Torpedo commands are passed by means of the speaker system.
		The main power supply for the torpedo fire control system are: 55 V AC taken from the torpedo fire control converter, which is located in the E motor room, under the ceiling, and 220 V DC taken through the switch and fuse boxes of the command circuit in the control room. The converter is powered from auxiliary switchboard 3 (light – regulated part).
		The torpedo launching system is powered by 220 V DC taken through the switch and fuse boxes from the signal circuit in the control room.
		The torpedo orders indicating system is used to pass commands from the conning tower to the aft torpedo room. It consists of the transmitter and receiver with indicator unit located in the conning tower and the receiver indicator with answering transmitter located in the aft torpedo room. The system is powered from ordering and reporting group 1.

	11.	Shaft mine launching reporting installation.
		The current state of the mine shafts is shown by means of the shaft mine reporting installation. The installation shows the state of the mine launching gears by means of the dedicated indicator boxes.
		Indicator box I (launching gears 1 – 18) located in the forward mine room and II located in control room are connected in parallel. Boxes III and IV (gears 19 – 65 starboard) and V and VI (gears 20 – 66 port) are located in the control room on the respective side.
		The installation consists of contactors coupled with the locking plates of the launching gears and the indicator boxes at the mine launching stations. At the indicator boxes there are labeled indicator glasses,

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12	IX. E installation	U-boat Information

i.e. for the mine shaft 1:

1st. Mine	2nd Mine	3rd Mine
loaded	empty	empty
fixed	loaded	empty

and so on.

So at any time the loading state of the shafts can be viewed. The installation is powered through the main switch from ordering and reporting group 1a through auxiliary switchboard 1 and 3.

Signal equipment.

1.	General information and power supply.
	The running lights installation is powered through the main switch of the command and signal circuit in the control room from auxiliary switchboard 2 or 3 (light – regulated part).
	The main switch for the running lights is located in the conning tower port, forward, at the main rudder steering station and enables quick switching on and off of all lights.
	The hand search light used for signaling can be powered from two locations. First – from ordering and reporting group 1a through the voltage divider (220/24 V) and second – from the 6 kVA and 1.5 kVA converter, the main switch and transformer (220/24 V).
	Additionally, a 30 cm – diameter bulb search lamp is provided. This is powered from the torpedo fire control system through the transformer (50/24 V ~).

2.	Running lights installation.
	At the switch, fuse and lamp box of the running lights circuit in the conning tower, the line branches through switches and resistors to the following lights:
	1. Stern lights
	2. Side light port
	3. Side light starboard
	4. Steaming light
	5. All-round light.

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U-boat Information	IX. E installation	13

	For 1. The lights are located at the upper deck, aft and at the aft edge of the conning tower casing. Both stern lights have associated dimmer resistors with control lamps, selector switches and dimmer switches, all located in the conning tower.
	1. Selector switch: light at the conning tower; light at the upper deck, aft
	2. Dimmer switch: dark, bright

	For 2. The line for the side light port passes through the port side of the pressure hull and leads to the pressure-proof side light.

	For 3. The line for the side light starboard passes through the starboard side of the pressure hull and leads to the pressure-proof side light.

	For 4. The steaming light when used, is attached to the forward conning tower periscope and connected into pressure-proof socket at the bridge (middle, forward). The main switch for the steaming light is located in the conning tower, as well as the second socket for the connecting the light.

	For 5. Over the steaming light, at the conning tower periscope, an all-round light is attached. The cable is led through the conning tower hatch and plugged in the conning tower, at starboard side. It is provided with a Morse-keying switch.

3.	Searchlight equipment.
	Each boat is equipped with a hand searchlight and a bulb searchlight, powered by 24 V AC. The searchlight can also be powered from ordering and reporting group 1a. The corresponding sockets are located in the conning tower (port) and at the bridge (port).
	The bridge socket for the searchlight is of pressure-proof construction. The socket for the bulb searchlight is in the conning tower.

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14	IX. E installation	U-boat Information

	Both searchlights are powered from the torpedo fire control converter. Converter output voltage (50 V) is transformed to 24 V. The line powering the transformer branches from the main switch box of the torpedo fire control system in the control room.
	The bulb searchlight is connected in the conning tower and its cable is led through the conning tower hatch.

Electric welding equipment.

The port E motor can also be used as a high current generator for arc welding.

U-Boat Type XB	B. Machinery Installations	Page 155

U-boat Information	Enclosures 1 - 5	1

C. Appendix.

= = = = = = = = =

1.	Boat silhouette
2.	Installations plan (Horizontal section)
3.	Installations plan (Length section)
4.	Tanks arrangement and trim table
5.	Blowing, emergency blowing and ventilation piping (2 enclosures)

	Click on the thumbnails below to view a full sized diagram and key
	Appendix 1	Boat silhouette
	Appendix 2	Installations plan (Horizontal section)
Missing	Appendix 3	Installations plan (Length section)
	Appendix 4 & 5	Tanks arrangement and trim table
	Appendix 6 Plate 17	Ballast tank flooding and venting installation, exhaust gas blowing and diver emergency blowing equipment
	Appendix 7 Plate 18	Blowing and emergency blowing equipment, piping for pressurizing regulating tanks
	Appendix 8 Plate 19	Compartment and battery ventilating systems

Anordung der Entlüftungsleitungen - Layout of the Vent trunks
druckfest ausgefürt	Pressure-proof construction
Entlüftungsanschluß	Gate valve
Entlüftungsventil	Vent valve
hinten	Aft
Notverschlußklappe	Emergency vent (flap) valve
Tauchz.	Main ballast tank
Traverse	Cross-connection
Treibölb.	Fuel oil tank
vorn	Forward