Balao - class submarine The " Balao " - class was a successful design of United States Navy submarine used during World War II , and with 122 units built , 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 . " Tang " actually achieved a depth of during a test dive , and exceeded that test depth when taking on water in the forward torpedo room while evading a destroyer . Propulsion . The propulsion of the " Balao " - class submarines was generally similar to that of the preceding " Gato " - class . Like their predecessors , they were true diesel - electric submarines : their four diesel engines powered electrical generators , and electric motors drove the shafts . There was no direct connection between the main engines and the shafts . " Balao " - class submarines received main engines from one of two manufacturers . Fairbanks - Morse supplied Model 38D8⅛ opposed piston engines , and General Motors ' Cleveland Diesel division supplied Model 16 - 248 and 16 - 278A V16 engines . Earlier Fairbanks - Morse boats received a 9 - cylinder version of the Model 38D8⅛ , while boats from onward received 10 - cylinder engines . Earlier GM boats received Model 16 - 248 engines , but beginning with Model 16 - 278A engines were used . In each case , the newer engines had greater displacement than the old , but were rated at the same power ; they operated at lower mean effective pressure for greater reliability . Both the F - M and GM engines were two - stroke cycle types . Two submarines , and , were to receive Hooven - Owens - Rentschler ( H . O . R . ) diesels , but both boats were cancelled . Two manufacturers supplied electric motors for the " Balao " - class . Elliott Company motors were fitted primarily to boats with Fairbanks - Morse engines . General Electric motors were fitted primarily to boats with General Motors engines , but some Fairbanks - Morse boats received GE motors . Allis - Chalmers motors were to be used in SS - 530 through SS - 536 , but those seven boats were cancelled before even receiving names . Earlier submarines carried four high - speed electric motors ( two per shaft ) , which had to be fitted with reduction gears to slow their outputs down to an appropriate speed for the shafts . This reduction gearing was very noisy , and made the submarine easier to detect with hydrophone s . A handful of late " Balao " - class submarines received low - speed double armature motors which drove the shafts directly and were much quieter , but this improvement was not universally fitted until the succeeding " Tench " - class . As the diesel engines were not directly connected to the shafts , the electric motors had to drive the shafts all the time . The " Balao " - class was successful , and one of its class brought down what remains the largest warship sunk by a submarine , the Japanese aircraft carrier " Shinano " ( 59 , 000 tons ) . Operational submarines . As of 2007 , a " Balao " - class submarine , was one of the last two operational submarines in the world built during World War II . It was transferred to Taiwan in the early 1970s . Museums . Eight " Balao " - class submarines are open to public viewing . They primarily depend on revenue generated by visitors to keep them operational and up to U . S . Navy standards ; each boat gets a yearly inspection and a " report card " . Some boats , like " Batfish " and " Pampanito " , encourage youth functions and allow a group of volunteers to sleep overnight in the crew ' s quarters . The following is a complete list of " Balao " - class museum boats :