Tang - class submarine The " Tang " class submarines were a product of the Greater Underwater Propulsion Power Program ( GUPPY ) , which incorporated German U - boat technology into the United States Navy ' s submarine design . They comprised the state of the art in post - World War II conventionally powered submarine design ; a design that was incorporated into and replaced by the nuclear - powered submarines of the 1950s and beyond . Design . One of the first innovations incorporated into the " Tang " s was the General Motors 16 - 338 lightweight , compact , high - speed " pancake " engine . Very different from the classic diesel engines that nearly all preceding submarines used , which were laid out with a horizontal crankshaft and two bank s of eight cylinders each , this new engine had a vertical crankshaft , and the cylinders were arranged radially like an aircraft engine . Four of these 13½ - foot - tall ( 4 . 1 m ) , , eight - ton engines could be installed in a single engine room , thus deleting an entire compartment from the submarine ' s design . The torpedo tubes were also redesigned . The six forward tubes now used a slug of water behind the torpedo to push it out , rather than the pulse of air used in previous designs . Because this design is somewhat quieter and does not release an air bubble every time a torpedo is fired , it has been used in all subsequent submarine designs throughout the world . The four stern tubes of previous classes were reduced to two shorter , simpler tubes that could not accommodate the longer anti - ship torpedoes and had no capability to actively eject torpedoes . Rather , they were designed for the Mk 27 and planned Mk 37 swim - out weapons . In addition , " Tang " s would use the HY42 ( yield stress ) steel . ( The new HY75 would not appear until the middle 1950s . ) Her design planned for speed and closed cycle propulsion ( as would the contemporary " Porpoise " and " Narval " classes . Boats . In October 1946 , the first two boats were ordered . was built at Portsmouth Naval Shipyard ; at the Electric Boat yard in Groton , Connecticut . In 1947 , contracts were awarded to Portsmouth for and to Electric Boat for . Then in 1948 , a similar pair of contracts were awarded for and . Their names were based on six US submarines lost during the war , of which most of their commanding officers were killed in action while combatting Japanese surface vessels : , , , , and . Construction and delivery followed without significant difficulty , but when the boats went to sea in the early 1950s , the new engines did not work well . Their compact design made them difficult to maintain , and they tended to leak oil into their generators . In 1956 , the Navy decided to replace the " pancake " engines with ten - cylinder Fairbanks - Morse opposed - piston diesels . To accommodate the larger engines , the boats had to be lengthened some nine feet in the engine room , and even then , only three could be installed . Accordingly , in 1957 and 1958 , the first four " Tang " s were lengthened , while " Gudgeon " and " Harder " , still on the ways , were built to the new length , with the new engines . In 1967 , " Tang " , " Wahoo " , " Gudgeon " , and " Harder " received an additional 15 - or 18 - foot ( ) section added to receive the PUFFS passive sonar installation . Museum Ships . Two boats of this class , " Tang " and " Gudgeon " , are preserved as museum ships in Turkey .