SS-418 USS Thornback

Namesake. The Thornback, a slender member of the shark family
Builder. Portsmouth Naval Shipyard, Kittery, ME
Laid down. 5 Apr 1944
Launched. 7 Jul 1944
Commissioned. 13 Oct 1944
Decommissioned. 6 Apr 1946
Recommissioned. 2 Oct 1953
Decommissioned. 1 Jul 1971
Stricken. 1 Aug 1973
Fate. Transferred to Turkey, 1 Jul 1971, sold to Turkey 1 Aug 1973
Class and type. Tench-class diesel-electric submarine
Displacement:
1,570 tons (1,595 t) surfaced
2,416 tons (2,455 t) submerged
Length. 311 ft 8 in (95.00 m)
Beam. 27 ft 4 in (8.33 m)
Draft. 17 ft (5.2 m) maximum
Propulsion
4 × Fairbanks-Morse Model 38D8-⅛ 10-cylinder opposed piston diesel engines driving electrical generators
2 × 126-cell Sargo batteries
2 × low-speed direct-drive General Electric electric motors
two propellers
5,400 shp (4.0 MW) surfaced
2,740 shp (2.0 MW) submerged
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
6 forward, 4 aft)
28 torpedoes
1 × 5-inch (127 mm) / 25 caliber deck gun
Bofors 40 mm and Oerlikon 20 mm cannon

General characteristics (Guppy IIA)
Displacement:
1,848 tons (1,878 t) surfaced
2,440 tons (2,479 t) submerged
Length. 307 ft (93.6 m)
Beam. 27 ft 4 in (8.3 m)
Draft. 17 ft (5.2 m)
Propulsion:
Snorkel added
One diesel engine and generator removed
Batteries upgraded to Sargo II
Speed. 17.0 knots (31.5 km/h) maximum, 13.5 knots (25.0 km/h) cruising (Surfaced); 14.1 knots (26.1 km/h) for ½ hour, 8.0 knots (14.8 km/h) snorkeling, 3.0 knots (5.6 km/h) cruising (Submerged)
Armament:
10 × 21 inch (533 mm) torpedo tubes
(six forward, four aft)
all guns removed