3A1. General. A modern submarine contains, in addition to the mechanisms required
to operate it on the surface, a multitude of operating machinery and tanks required to enable it to
dive, surface, and proceed submerged. This fact makes it one of the most compact vessels afloat.
Yet the submarine is designed and arranged along simple and logical lines, and in spite of the
seeming confusion of valves, lines, and apparatus, everything in the submarine is situated to insure
the maximum of speed and efficiency. (See FigureA-1.)
The modern fleet type submarine consists of a superstructure and a hull surrounded for the
most part by various fuel and water ballast tanks. The pressure hull, designed to withstand the sea
pressure, houses most of the ship's machinery and provides the living quarters for the officers and
the crew. It is divided into eight watertight compartments, separated by pressure bulkheads
provided with watertight pressure resistant doors. The ninth compartment, the conning tower, in
the shape of a cylinder placed on its side, is located above the control room and connects with the
control room through the access hatch.
The compartments, in turn, are divided by means of the platform deck into upper and lower
sections, which contain the spaces housing the various equipment and providing the necessary
facilities for the submarine's officers and crew.
3A2. Forward torpedo room. The foremost compartment in the submarine is the
forward torpedo room (See Figure 3-1.), located between frames 16 and 35. The forward
torpedo room contains six torpedo tubes in its forward bulkhead; torpedo racks on its port and
starboard sides, immediately adjacent to the torpedo tubes for carrying
spare torpedoes; torpedo loading hatch overhead; and torpedo handling equipment. Four of the
torpedo tubes, Nos. 1, 2, 3 and 4, are above the platform deck, while tubes Nos. 5 and 6 are
below the platform deck. The sonar gear, underwater log, and an access hatch to the escape
trunk are also located in the forward torpedo room.
The following is a list of the more important equipment located in the forward torpedo room:
Hydraulic pump and ram for bow plane tilting
Hydraulic motor for windlass and capstan and bow plane rigging
Impulse charging manifolds (port and starboard)
Torpedo tube blow and vent manifold
Torpedo tube drain manifold
Torpedo gyro regulators
Blow and vent manifold for normal fuel oil tanks No. 1 and No. 2
Blow and vent manifold for No. 1 sanitary tank
Blow and vent manifold for fresh water tanks No. 1 and No. 2
Bunks and lockers for crew (usually at least 10 men)
High and low external compartment air salvage valves
Compartment air salvage (internal)
Bow buoyancy vent operating gear
No. 1 main ballast tank vent operating gear
Figure 3-1. Forward torpedo room.
Figure 3-2. Forward battery compartment.
3A3. Forward battery compartment. (See Figure 3-2.) The forward torpedo room is
separated from the forward battery compartment by a watertight bulkhead and door. The lower
part of the forward battery compartment houses the 126 forward battery cells. The upper section
of the compartment contains the officers' quarters, the chief petty officers' quarters, and the
yeoman's office. The entire forward battery compartment is located between frames 35 and 47.
The officers' quarters provide wardroom and staterooms for the ship's officers, sleeping
accommodations for the chief petty officers, and officers' showers and pantry.
Also located in the forward battery compartment are:
Ventilation supply lines
Ventilation exhaust lines
Main ballast tanks No. 2A-2B vent operating gear
External salvage air connections (one high and one low)
Compartment internal salvage air connections
3A4. Control room. (See Figures 3-3, 3-4, and 3-5.) Going aft, the compartment
immediately adjoining the forward battery compartment is called the control room. It is
located between frames 47 and 58 and is the main control center of the submarine. The control
Starboard side forward-aft:
Electric circuits and switchboard (IC switchboard)
High-pressure air manifold
225-pound air manifold
600-pound main ballast tanks blowing manifold
10-pound main ballast tanks blowing manifold
Auxiliary power switchboard
Main ballast tanks Nos. 2A and 2C
Port side forward-aft:
Gun access batch
Oil supply tank
Hydraulic air-loading manifold
Negative tank inboard vent
Bow and stern plane diving station
Main ballast tanks Nos. 2B and 2D emergency vents
Pump room hatch
In the overhead:
High and low external compartment air salvage
Internal compartment air salvage
Ventilation supply and exhaust lines
In the pump room:
Hand and hydraulic operating gear for negative flood
High pressure air compressors
IC motor generators
Figure 3-3. Control room (starboard side) and radio room
Figure 3-4. Control Room
Figure 3-5. Pump Room
The after section of the control room is occupied by the radio room which houses the
transmitting and receiving radio apparatus, and radio direction finder. The engine induction and
ship's supply outboard valve operating gear is located in the radio room overhead.
Access to the radio room is from the control room, which is in turn is accessible from the
officers' quarters passageway forward, crew's mess hall aft, and the conning tower access hatch
3A5. Conning tower. The compartment immediately above the control room is the
conning tower. (See Figure 3-6.) It is the main navigation and firing control station for
the submarine. The conning tower contains the periscopes and the periscope hoist equipment, the
radio direction finder, the sonar equipment, the radar equipment, the torpedo data computer
(TDC), the gyro repeater, the conning tower steering stand, and the various pressure gages and
The conning tower connects with the control room through a watertight hatch. This is
designated as the lower conning tower hatch. The upper conning tower hatch provides
access to the bridge from the conning tower. The conning tower also has a ventilation exhaust
connection and its own air-conditioning coil. Since the conning tower is the commanding
officer's battle station, all communication lines include the conning tower in their circuits.
3A6. After battery compartment. The compartment aft of the control room is the
after battery compartment (See Figure 3-7.), located between frame 58 and frame 77. It houses
the after battery with its 126 cells below the platform deck. The battery cells are connected to the
exhaust system by ducts leading to the battery blowers. The forward end of the after battery
space, below decks, also contains the cool and the refrigerating
rooms and the ammunition magazine. Above the platform deck, the after battery compartment
contains the crew's galley, mess hall, and the crew's sleeping quarters.
The more important equipment in the after battery compartment consists of emergency vents
for safety tank, FBT No. 3 and No. 4; hand-operated flood valves for FBT No. 3 and No. 4; main
vent operating gear for safety tanks, MBT No. 2C and 2D, FBT No. 3A and 3B, FBT No. 4A and
4B, and FBT No. 5A and 5B; the hydrogen-detecting apparatus; the blow and vent manifold for
fuel ballast tanks No. 3A and 3B, 4A and 4B. The galley equipment, scuttlebutt, battery exhaust
blowers, and the radio receiver for the crew are also located in the after battery compartment.
The after part of the after battery compartment contains the crew's bunks (usually 36) with
individual lockers for each bunk and a medicine locker. Separated from it by a non-watertight
bulkhead and a door are the crew's head, showers, washing machine, and lavatories.
The after battery compartment is provided with an external high and low compartment
salvage air valve.
3A7. Forward engine room. The forward engine room (See Figure 3-8.) is located
between frames 77 and 88, and houses No. 1 and No. 2 main engines. The main engines extend
from below the platform deck into the engine room space, with No. 1 main engine on the
starboard side and No. 2 main engine on the port side. The main generators, No. 1 and No. 2, are
below decks aft of the main engines beneath the platform deck, and are directly connected to
The forward engine room houses the vapor compression distillers, fuel oil pump (standby),
lubricating oil pump (standby), engine air inboard induction hull valve, and various main engine
starting and stopping controls.
Figure 3-6. Conning tower
Figure 3-7. After battery compartment and crew's quarters.
Figure 3-8. Forward engine room
The forward engine room also contains the following:
High and low external compartment air salvage connection
Internal compartment air salvage connection
Hull ventilation supply valve
Fuel oil purifier
Lubricating oil purifier
3A8. After engine room. The after engine room (See Figure 3-9), located between
frames 88 and 99, is similar in many respects to the forward engine room. It houses the No. 3 and
No. 4 main engines and main generators.
In addition, the after engine room houses the auxiliary generator and the auxiliary diesel
engine, both of which are located entirely below the platform deck.
The upper space of the after engine room houses the after engine air inboard induction hull
valve, the high and low external compartment air salvage connection, the internal compartment air
salvage valve, the lubricating oil and the fuel oil purifiers and the pumps. The compartment also
Standby fuel oil pump
Standby lubricating oil pump
Hull supply lines (ventilation)
3A9. Maneuvering room. (See Figures 3-10
and 3-11.) The upper section of the maneuvering room, frames 99 to 107), contains the
maneuvering control stand, indicators, gages, lathe, crew's head, auxiliary switchboard, remote
control for engine shutdown, oxygen flask, high and low external compartment air salvage,
internal compartment air salvage, maneuvering room induction hull valve, hull supply lines, and
The lower part of the maneuvering room is called the motor room and has the Nos. 1, 2, 3,
and 4 main motors. The four main motors are directly connected with the two reduction gears.
The main motors Nos. 1 and 3 are directly connected with the reduction gear No. 1, and the main
motors Nos. 2 and 4 are directly connected with reduction gear No. 2. The reduction gears in
turn are connected with the propeller shafts.
The circulating water pumps and the lubricating oil pumps are also located in the motor
3A10. After torpedo room. The aftermost compartment on the submarine is the after
torpedo room (See Figure 3-12), located between frame 107 and 125. Unlike the forward
torpedo room, it contains only four torpedo tubes in its after bulkhead. However, it also has the
torpedo racks, torpedo handling equipment, and spare torpedoes.
The after torpedo room has one impulse charging manifold, torpedo tube blow and vent
manifold, torpedo gyro regulators, and the torpedo tube firing indicator and controls. It also
contains the escape and rescue hatch, the torpedo loading hatch overhead, the hydraulic steering
rams and pump, the stern place tilting mechanism, the torpedo tube drain manifold, the crew's
bunks and lockers, the ventilation supply line, the bulkhead flappers, the oxygen flasks, the
emergency air connection for escape hatch, the high and low external air salvage connections, the
internal compartment air salvage, and a sound-powered telephone.
Figure 3-9. After engine room
Figure 3-10. Maneuvering room above platform deck
Figure 3-11. Motor room
Figure 3-12. Maneuvering room above platform deck
B. EXTERIOR INSTALLATIONS
3B1. General.The exterior view of the submarine presents a very low silhouette.
This is due primarily to the fact that the submarine is designed to have a low center of gravity for
stability and is normally two-thirds submerged as she rides on the surface.
The exterior hull of the submarine has a cylindrical shape, which gradually tapers forward of
frame 35 and aft of frame 107, becoming the bow of the superstructure and the rounded stern.
The superstructure deck, called the main deck, extends virtually from the tip of the
bow to frame 124 near the stern. The deck is generally level. Beginning about the midship section
it rises gradually in the direction of the bow, to a height of approximately 12 feet above the water
line. The freeboard of the after end of the main deck is about 4 feet.
The main deck is attached to the exterior hull by means of the framing and rounded sides.
Limber holes in the sides allow sea water to enter all the hollow spaces in the superstructure and
the deck when diving, and drain off when the submarine is surfacing.
The midship section of the main deck is occupied by the conning tower, which is surmounted
by the bridge deck, with periscope shears, periscopes, radio compass loop, and radar antenna.
The after section of the bridge deck contains the ship's pelorus, one 20-mm anti-aircraft
gun and after ammunition ready locker, while the forward section of the bridge may have
either a 20-mm or a 40-mm anti-aircraft gun, depending upon the particular ship. Two
ammunition ready lockers are located in the lower part of the conning tower superstructure, one
forward and one aft. The gun access trunk is located forward and one aft. The gun access trunk
is located forward of the conning tower and is provided with a hatch opening onto the main deck.
The forward section of the deck contains the 5"/25 wet type gun, galley access hatch, after
engine room access hatch, after torpedo loading hatch, after rescue and escape hatch, marker
buoy, and capstan.
The bow is equipped with six torpedo tube shutters, three on the port and three on the
starboard side, and the bow diving planes.
The underside of the hull contains ballast tank flooding ports and underwater sound heads.
The after end of the ship, on the underside, is equipped with the four stern torpedo tubes,
two on the port and two on the starboard side, port and starboard propeller struts, propellers,
stern diving planes, and the rudder.