This compartment houses the Number One and Number Two main engines. There is a platform deck between them. About one-half of the engine and a generator for each is below this deck. Each of these 16-cylinder diesel engines produce 1,600 horsepower and directly drives its 1,100 kilowatt DC electrical generator. In the Diesel-Electric system used by the U.S. Navy the engines are not mechanically connected to the propellers but only produce electrical power. The submarine's propellers are driven by electric motors at all times. Electrical power for these motors can come from either the batteries (while submerged) or the diesel-driven generators when running on the surface. COD's engines were built in Cleveland, Ohio by the Cleveland Diesel Division of General Motors.
At the forward end of the room are the two fresh water distilling plants. Each of these can produce up to forty gallons of very pure water per hour. After they were lit off, it took an hour or longer to start making water, and no less than 600 gallons were used per day. They were in constant operation almost all the time the submarine was on the surface.
The water from the stills had to be tested every forty gallons. That was done to see if it was absolutely salt free. Salt free water went into the battery water tanks to be used to make up for water lost by the batteries through evaporation and electrolysis. Even a small amount of salt in this water would react with the acid in the batteries to form deadly chlorine gas.
The distilling plants on board U.S. submarines provided plenty of fresh water for the needs and comfort of the crew. The showers and clothes washing machine were in routine use, and the mess cooks never had to improvise for clean fresh water for cooking or washing dishes.