Mackerel-class submarine

USS Mackerel (SS-204)
Class overview
Name	Mackerel class
Builders	Electric Boat Company Portsmouth Naval Shipyard
Operators	United States Navy
Preceded by	Tambor class
Succeeded by	Gato class
Built	1939–1941
In commission	1941–1945
Completed	2
Retired	2
General characteristics (Mackerel)
Type	Diesel and electric submarine[2]
Displacement	825 tons (838 t) surfaced[1] 1,190 tons (1,209 t) submerged[1]
Length	243 ft 1 in (74.09 m)[1]
Beam	22 ft 1 in (6.73 m)[1]
Draft	13 ft 0+1⁄4 in (3.969 m)[1]
Propulsion	2 × Electric Boat direct drive diesel engines[2] 2 × 60-cell Sargo batteries[1] 2 × Electro Dynamic electric motors[2] 2 shafts[2] 1,680 bhp (1,250 kW) surfaced[2] 1,500 bhp (1,100 kW) submerged[2]
Speed	16 knots (30 km/h) surfaced[2] 11 knots (20 km/h) submerged[2]
Range	6,500 nautical miles (12,000 km) at 10 knots (19 km/h) (service)[1]
Test depth	250 ft (76 m)[1]
Complement	4 officers, 33 enlisted[1]
Armament	6 × 21-inch (533 mm) torpedo tubes  (four forward, two aft)  12 torpedoes[1] 1 × 3-inch (76 mm)/50 caliber deck gun[1]
General characteristics (Marlin)
Type	Diesel-electric submarine[2]
Displacement	800 tons (813 t) standard, surfaced[1] 1165 tons (1184 t) submerged[1]
Length	238 ft 11 in (72.82 m)[1]
Beam	21 ft 7+1⁄4 in (6.585 m)[1]
Draft	13 ft 0+1⁄4 in (3.969 m)[1]
Propulsion	2 × ALCO diesel engines driving electrical generators[2] 2 × 60-cell Sargo batteries[1] 2 × General Electric electric motors[2] 2 shafts[2] 1,700 bhp (1,300 kW) surfaced[2] 1,500 bhp (1,100 kW) submerged[2]
Speed	14.5 knots (27 km/h) surfaced[1] 9 knots (17 km/h) submerged[1]
Range	7,400 nautical miles (13,700 km) at 10 knots (19 km/h)[1]
Test depth	250 ft (76 m)[1]
Complement	4 officers, 34 enlisted[1]
Armament	6 × 21-inch (533 mm) torpedo tubes  (four forward, two aft)  12 torpedoes[1] 1 × 3-inch (76 mm)/50 caliber deck gun[1]

The Mackerel-class submarines were a pair of experimental prototype submarines built just prior to World War II and launched in 1940 and 1941. The two submarines were similar in size and capability to the S-class submarines built at the end of World War I, and had been ordered to test the feasibility of using mass production techniques to build small submarines. Until at least 1940 it was thought that mass production of fleet submarines would be impractical, and in any case small submarines could provide area defense for submarine bases.^[3] Once it became apparent that there would be sufficient production of the more capable Gato-class submarines, interest in the design waned and no additional small submarines were ordered. Submarine production standardized during the war on the Gato class and its successors, the Balao and Tench-class submarines. In some references, the Mackerels are called the "M class".^[4]