THE WORLD WAR II FLEET CLASS SUBMARINE
by: Jack Higgins and Paul Wittmer

World War II Submarines:
The United States had a variety of submarine classes used during WWII. The "S" Class boats saw much service as well as other older classes. The majority of U.S. Submarines used in WWII were the long-range fleet class boats. Until the advent of the nuclear submarines all U.S. submarines were really surface craft that had the ability to submerge for limited periods of time. Most of the operations were on the surface where the Diesels were used to produce propulsion at speeds approaching 22 knots, especially when someone was chasing you. At high speeds the fuel consumption was rapid. An efficient combination of using three engines was often utilized to get to your operating areas.

Diving:
Diving was done daily in order to adjust the trim of the boat and to determine the salinity of the water at different depths. A war time dive could be completed in 30 seconds. A submarine going into a dive causes a shifting of the center of gravity and the center of buoyancy. The metacenter is a point where the center of gravity of the boat coincides with the center of buoyancy; a very hazardous point which must be passed quickly. If the center of gravity and the center of buoyancy are coincident and if a wave were to hit the boat from the side, capsizing could occur. Those Hollywood movies where a submarine is shown with decks awash, making an approach on the surface is mostly fiction. That is about where the two centers become coincident and it doesn't take much to roll the boat over.

Cruising while submerged required all those air gulping machines, the Diesels to be stopped quickly and intake air and exhaust gas openings sealed within a matter of seconds. Cruising while submerged reduced the visibility range and the cruising speed was usually cut to 3 knots to conserve the batteries. The maximum speed submerged was about 9 knots, used only for very short periods and emergencies.

Submerged propulsion was by means of the four 1500 HP each, main electric motors coupled to two reduction gear sets, one for the Port and one for the Starboard shaft. Long submergence was limited to battery capacity and crew viability because of the consumption of oxygen. Usually the off watch crews would relax to conserve energy and oxygen. Except during a battle situation, which required all hands to be alert and prepared for any eventuality; and there were many!

Surfacing:
To surface a fleet type boat, the alarm would be sounded, high pressure air from the air flasks which is stored air at 3,000 pounds per square inch, would be fed into the ballast tanks. At the same time the planesmen would cause the bow and stern planes to permit the boat to rise. Upon surfacing, the conning tower hatch would be cracked to permit any excess air that built up in the boat during the dive to escape. This build up of a few inches of pressure was caused by venting certain tanks inboard during the last dive. After the main induction valves, which supply air to the engines, are opened, then engines would be started. The high speed, low pressure, blowers would be turned on, to remove as much water from the ballast tanks without wasting the precious high pressure air.

On the surface the two high-pressure four stage air compressors would be started to replenish the air banks; an operation know as jamming air.

The Diesels:
On the fleet type boats there were four main 1500 HP Diesels, each one coupled to an 1100 KW Generator. Each Diesel would turn it's own generator, producing electrical power which was routed to the control cubicle, operated by the electricians in the Maneuvering Room. They in turn would answer the signals from the bridge or conning tower for the ship's speed and what engines would be devoted to charging the batteries. Batteries had to be charged often, usually every night and before a battle situation.

There were two popular Diesels used on the fleet boats, the Fairbanks Morse opposed piston Diesel which had no valves for intake or exhaust and the 16 cylinder (Winton) or General Motors Diesels which had four valves in each cylinder head. Fleet boats also had a smaller auxiliary engine installed in the lower flats of the after engine room. This was often used for finishing a battery charge.

Older boats used different combinations of direct drives via clutches and reduction gears and they incorporated other types of Diesels.

Fuel Storage:
The fuel was stored outside the pressure hull in a series of tanks. No fuel tank was permitted to have air in the tank, else the tank would collapse if submerged. So the fuel, which was lighter than sea water was drawn off from the top of a fuel tank permitting sea water to compensate in order to keep the fuel tanks full of a liquid at all times. There was an exception when fuel was consumed from the fuel ballast tanks, these few tanks would be converted at sea to operate as additional main ballast tanks; thereby permitting the boat to ride higher and run at greater surface speeds.

Fresh Water:
How did we make fresh water?
There were two kinds of fresh water. There was the drinking water (potable) and then there was the condensate water. Let us describe each, one at a time so that a better understanding can be made.
1) The potable water is the most simple to describe.
In the forward engine room there were located two Kleinschmidt Vapor Compression Stills. These stills used an intake of seawater that was all about us. This water was heated to the boiling point. The vapors given off were then passed on to a set of cooling coils to condense and separate the vapors back into liquid water and brine. The two liquids were extracted. The brine was eventually pumped to sea after dumping into the bilge. The resulting "fresh" water is then distributed to the all areas requiring distilled water for use. The most abundant use is that required for cooking, and eating, coffee, dish washing, and the like. A smaller amount is double distilled and taken off in a highly pure form for use in maintaining the liquid level of the batteries. These stills were operated at night, while on the surface and it was a very hot job. If someone were caught wasting fresh water, he would get a turn at the stills. It is not unusual for the man who operates the stills to lose as much as 15 pounds during a patrol.
2) The condensate water:
The general temperature of the ocean water is a little cooler than the air temperature above the water. As one submerges and descends to lower depths the temperature decreases even further. This decline in the water temperature is not necessarily related to the depth. In fact it may follow an unusually radical nonlinear relationship as compared to the depth of the water. Since this relatively cool water surrounds the exterior of the submarine, this temperature is conducted to the interior, resulting in cold interior surface.

As all of the days efforts are performed such as cooking, physical activities, and the ever present seeping of water around gaskets and seals; water vapor permeates the atmosphere. The increasing humidity is counterbalanced by being deposited on the cool interior surfaces of the submarine. These dew like deposits condense to form droplets of water which in turn drop from the overhead or simply run down the bulkheads (sidewalls) to the bilge. This again was not the making for a comfortable environment for the crew.

Several methods to solve this problem were used such as applying a layer of insulation on the interior, but the most successful was accomplished by the use of a air conditioning condenser or dehumidifier to remove the moisture from the air. This piece of equipment was located in the forward engine room and assisted in the circulation of air throughout the entire boat (submarine).

Since a great deal of moisture is now gathered in one area the question arises as to what to do with this quantity of water. If it was dumped back to the bilge it would only serve to provide a surface for more vapor to escape to the air. Not really solving the problem at hand but only recirculating the vapors.

By putting this water into a separate holding tank eliminates the evaporation problem and provides another much needed supply of water. This water is used for bucket baths, laundry, and other non-consumption requirements. An older and usually wiser submariner would draw off the best condensate water into a bucket for his laundry or bucket bath only after the boat had been on the surface for awhile. The new man on board would soon learn, not to draw stinky condensate water after the boat had been submerged all day; when the condensate water contained all the sweat of the crew, cooking odors as well as whatever else was circulating in the air during an all day dive.

The Batteries:
How many and how big were the batteries?
The source of power for the motors while submerged cannot be supplied by the diesel engines, which would deplete the oxygen content of the air. However power can be stored in batteries while on the surface by the use of the Diesels and generators. These rechargeable batteries are just like the batteries used in the family automobile with one very big difference. Size.

Each battery is nearly 18 inches square and stands 4 and 1/2 feet in height and can deliver as much as 6000 amperes to the motors.

With only two (2) volts available at the terminals of such a battery it required at least 125 cells connected in series to supply the 250 volts necessary to run the electric motors of the boat. So much energy is required that the boats have two such battery banks. The first set is located below the deck of the officers quarters just forward of the control room and aft of the forward torpedo room. This compartment is known as the Forward Battery Compartment. The second set is located below the deck of the crews quarters which is located aft of the control room. This compartment known as the After Battery is divided into two basic sections. The forward section is devoted to the galley and crews mess. Below deck in this area in located the magazine (ammunition) and freezer compartments for the storage of food necessary for extended range operation.

The second section is a bit further aft and is the location of the crews sleeping quarters. Below the deck are the second set of batteries. A total complement of 250 individual cells make up the two banks of batteries each of which can supply 250 volts and 4000 amperes of current.

Inasmuch as the submarine is so dependent on the batteries it should be self evident that extreme care and attention is devoted to the batteries. During each watch it is the duty of electrician on watch to go below deck in each of the battery compartments to sample the gravity levels of the batteries. This is particularly of prime importance during a battery charge.

During a battery charge, pure hydrogen gas is emitted from each battery. Ventilation tubes cover each of the batteries and the gas is drawn off and vented overboard so that no explosive atmosphere is permitted to exist in the interior of the boat. All during a battery charge the "no smoking" light is out.

Armaments:
The primary purpose of a submarine was to sink enemy ships and the submarine's primary weapons was the torpedo. Launched by means of torpedo tubes, located both forward and aft. There were some topside guns used for fighting while on the surface. Usually one large caliber deck gun which could be any size from a 3" to the 5" which was installed on most fleet boats at the end of the war. Mounted on the level of the bridge, there may be 40mm deck guns or 20mm guns or some combination. Fifty caliber machine guns and other weapons were stowed below decks and brought topside during a battle surface operation.

The Crew's Watches:
A ship at sea requires a crew of men to man all stations at all times. There are no holidays, weekends, or Saturday nights, as we have known them.

The total crew is divided into three sections, which permits one section to man all stations, while two sections can rest, eat, study their qualification requirements or play cards or games. Any one section can dive or surface the boat or fire torpedoes if a very quick setup requires it.

The watches are set at four hours on duty with eight hours off duty for most normal cruising operations. There are exceptions. Every five days, there is a field day to clean up the boat and it is on this day, we get a chance to take a shower. Field days are held more often when preparing to enter port. The shower is limited to two minutes per man and nothing more. Another exception is the signal to go to battle stations, which requires all hands to man their respective station. This could be a call for "Battle Stations Submerged" or "Battle Stations Surface."

The War Patrol:
When all the shakedown and training trials are completed and the boat leaves for a war patrol; all the hatches except one, are secured with either chain falls or by the use of the double hatch device which was installed late in the war. We would not want a hatch to be pulled open by the suction created during a close depth charge attack. The only hatch that remains accessible daily is the conning tower hatch.

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