The Tang class of submarines was 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.

One of the first innovations incorporated into the Tangs 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 rows 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, four-foot wide, 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 was shot, 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 antiship torpedoes and had no capability to actively eject torpedoes. Rather, they were designed for the Mk-27 and planned Mk-37 swim-out countermeasure weapons.

In October 1946, the first two boats were ordered. Tang (SS-563) was built at Portsmouth Naval Shipyard; Trigger (SS-564) at the Electric Boat yard in Groton, Connecticut. In 1947, contracts were awarded to Portsmouth for Wahoo (SS-565) and to Electric Boat for Trout (SS-566). Then in 1948, a similar pair of contracts were awarded for Gudgeon (SS-567) and Harder (SS-568). 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 Tangs were lengthened, while Gudgeon and Harder, still in the ways, were built to the new length, with the new engines.

In 1967, Tang (SS-563), Wahoo (SS-565), Gudgeon (SS-567), and Harder (SS-568) received an additional 15-or-18-foot section added to receive the PUFFS passive sonar installation.

General Characteristics

• Displacement: 1560-2050 tons surfaced, 2260-2700 tons submerged
• Dimensions: 268 feet, extended to 287 feet, then to 302 feet
• Beam: 27 feet
• Draft: 17 feet
• Armament: six 21-inch torpedo tubes forward, two aft
• Propulsion: twin shaft, electric motor, GM 16-338 "pancake" engines replaced by Fairbanks 38D8-1/8 opposed piston engines
• Speed: 15.5 knots surfaced, 18.3 knots submerged
• Endurance: one hour at 17.5 knots on battery; 10,000 nautical miles at 10 knots on snorkel
• Depth: 700 feet
• Complement: eight officers, 75 men

Submarines