|Builders:||Portsmouth Naval Shipyard, Electric Boat Company, Boston Navy Yard|
|Operators:|| United States Navy
Republic of China Navy
Royal Canadian Navy
|Preceded by:||Balao class|
|Succeeded by:||Barracuda class|
|Displacement:||1,570 tons (1,595 t) surfaced
2,416–2,429 tons (2,455–2468 t) submerged
|Length:||311 ft 8 in – 311 ft 9 in (95.0 m)|
|Beam:||27 ft 3 in – 27 ft 4 in (8.3 m)|
|Draft:||17 ft (5.2 m) maximum|
4 × diesel engines driving electrical generators (Fairbanks-Morse or General Motors)
|Speed:||20.25 knots (38 km/h) surfaced
8.75 knots (16 km/h) submerged
|Range:||11,000 nautical miles (20,000 km) surfaced at 10 knots (19 km/h)|
|Endurance:||48 hours at 2 knots (3.7 km/h) submerged
75 days on patrol
|Test depth:||400 ft (120 m)|
|Complement:||10 officers, 71 enlisted|
|Armament:||10 × 21-inch (533 mm) torpedo tubes
(six forward, four aft)
1 × 5-inch (127 mm) / 25 caliber deck gun
Bofors 40 mm and Oerlikon 20 mm cannon
two .3 or .5 in (7.62 or 12.70 mm) machineguns
Tench-class submarines were a type of submarine built for the United States Navy (USN) between 1944 and 1951. They were an evolutionary improvement over the Gato and Balao classes, only about 35 to 40 tons larger, but more strongly built and with a slightly improved internal layout. Further improvements were made beginning with SS-435, which are sometimes referred to as Corsair class.
Initial plans called for 146 to be built, but 115 were cancelled in 1944 and 1945 when it became apparent that they would not be needed to defeat Japan. The remaining 31 were commissioned between October 1944 (Tench) and February 1951 (Grenadier).
The as-built diesel-electric propulsion layout was the same as the last few Balao class, with four Fairbanks-Morse or General Motors two-stroke diesel engines supplying two low-speed double-armature electric motors to drive two shafts. The direct-drive electric motors were much quieter than the reduction gear arrangement of previous classes. Two 126-cell Sargo-type lead-acid batteries provided submerged power to the electric motors.
Many targets in the Pacific War were sampans or otherwise not worth a torpedo, so the deck gun was an important weapon. Due to war experience, most Tench class were armed with a 5 inch (127 mm)/25 caliber gun, and some boats had two of these. Additional anti-aircraft guns included single 40mm Bofors and twin 20mm Oerlikon mounts, usually one of each.
The Tench class submarine ex-Cutlass was transferred along with the Balao-class ex-Tusk to the Republic of China Navy as Hai Shih and Hai Pao in 1973. Two Tench-class boats went to Italy as the Gianfranco Gazzana-Priaroggia class. USS Argonaut (SS-475) was sold to the Royal Canadian Navy in 1968, renamed HMCS Rainbow, and decommissioned in 1974. SS-479 "Diablo" was leased to the Pakistani Navy in 1963 and then as PNS Ghazi participated in two further wars, finally sinking in action most likely due to a mine-laying accident with the loss of all 92 hands. Diablo thus was the last Tench-class submarine to see action in history.
Some of the class were updated through the GUPPY (The Greater Underwater Propulsion Power Program), primarily by increasing the battery capacity and streamlining the submarine's exterior. The difference is noticeable by the level foredeck and the rounded bow.
Three Tench Class submarines are on display for the general public.
- USS Requin (SS-481) at the Carnegie Science Center in Pittsburgh, PA.
- USS Torsk (SS-423), moored at Pier Three, Baltimore's Inner Harbor, (alongside the National Aquarium in Baltimore) in Maryland.
- USS Thornback (SS-418), on display at Rahmi M. Koç Museum, Golden Horn in Istanbul.
- Bauer, K. Jack; Roberts, Stephen S. (1991). Register of Ships of the U.S. Navy, 1775-1990: Major Combatants. Westport, Connecticut: Greenwood Press. pp. 280–282. ISBN 0-313-26202-0.
- Friedman, Norman (1995). U.S. Submarines Through 1945: An Illustrated Design History. Annapolis, Maryland: United States Naval Institute. pp. 285–304. ISBN 1-55750-263-3.
- U.S. Submarines Through 1945 pp. 305-311
- Lenton, H. T. American Submarines (Doubleday, 1973), p.101.
- Fleet Type Submarine Training Manual San Francisco Maritime Museum
- GUPPY and other diesel boat conversions page
Media related to Tench class submarines at Wikimedia Commons