The first compartment houses breech pieces of 6 torpedo tubes, spare torpedoes, food-store, stowage, compensating and forward trim tanks. The compartment also has combined torpedo loading and access hatch, electric drives of the windlass and forward diving planes, as well as kit lockers and crew’s hammocks.
The second compartment houses the first group of 60 accumulators; over it is a radio station and a sonar room.
The third compartment is a place for two groups of accumulators; over it are the living quarters and the officers’ messing room. The ship’s electric blowers and a galley are also located here. On the sides and under the accumulators there are fuel tanks.
The fourth compartment is reserved for the conning tower. It houses a command and control centre, a regulator tank and a negative-buoyancy tank, as well as the main bilge pump and one of the main ballast blowing plants, for the case of lifting.
In the fifth compartment, there is a fourth group of accumulators, surrounded by oil tanks; above it are petty officers’ living quarters and the second blowing plant for surfacing.
The sixth compartment is a diesel one. Each of the two diesel engines could develop power up to 1,200 hp at 450 rpm within one hour. Their continued operation was guaranteed at the capacity of 1,100 hp and 425 rpm. The compartment also houses screw shafts disengaging clutches, lubricating oil tanks, some auxiliary mechanisms and a special hatchway for the engine crew.
The seventh compartment, stern room, contains the main electric motors and their control stations, breech housing of 2 sternmost engines, a combined hatch, trim tank, steering gear and other auxiliary mechanisms, as well as hammocks for the crew.