The Balao class was a design of United States Navy submarine used during World War II, and with 120 boats completed, the largest class of submarines in the United States Navy. An improvement on the earlier Gato class, the boats had slight internal differences. The most significant improvement was the use of thicker, higher yield strength steel in the pressure hull skins and frames, which increased their test depth to 400 feet (120 m). Tang actually achieved a depth of 612 ft (187 m) during a test dive,
and exceeded that test depth when taking on water in the forward torpedo room while evading a destroyer.
USS Balao in 1944
Scheme of USS Pampanito (SS-383)
General Motors Cleveland Model 16-248 diesel engine
Fairbanks-Morse Model 38D8⅛ diesel engine
A submarine is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely operated vehicles and robots, as well as medium-sized or smaller vessels, such as the midget submarine and the wet sub. Submarines are referred to as boats rather than ships irrespective of their size.
US Virginia-class submarine underway in Groton, Connecticut, July 2004
Russian Akula-class submarine of the Northern Fleet, in 2008
An early submersible craft, built by Cornelis Drebbel, propelled by oars
1806 illustration by Robert Fulton showing a "plunging boat"