Salmon-class submarine

USS Salmon on trials in 1938
Class overview
Builders:	Electric Boat Company, Portsmouth Naval Shipyard, Mare Island Naval Shipyard
Operators:	United States Navy
Preceded by:	Porpoise class
Succeeded by:	Sargo class
Built:	1936–1938
In commission:	1937–1946
Completed:	6
Retired:	6
General characteristics
Type:	Composite (direct and diesel-electric) drive fleet submarine
Displacement:	1,435 long tons (1,458 t) standard, surfaced 2,198 long tons (2,233 t) submerged
Length:	308 ft (94 m)
Beam:	26 ft 1.25 in (7.96 m)
Draft:	15 ft 8 in (4.78 m)
Propulsion:	4 × General Motors-Winton or Hooven-Owens-Rentschler (H.O.R.) diesel engines (two direct drive, two driving electrical generators), 1,535 hp (1,145 kW) each 2 × 120-cell batteries 4 × high-speed Elliott geared electric motors, 665 hp (496 kW) each 2 × auxiliary diesel generators, 330 kW (440 hp) each 2 shafts Net 5,500 hp (4,100 kW) surfaced 2,660 hp (1,980 kW) submerged
Speed:	21 knots (39 km/h) surfaced 9 knots (17 km/h) submerged
Range:	11,000 nautical miles (20,000 km) at 10 knots (19 km/h)
Endurance:	48 hours at 2 knots (3.7 km/h) submerged
Test depth:	250 ft (76 m)
Complement:	5 officers, 54 enlisted
Armament:	8 × 21 inch (533 mm) torpedo tubes  (four forward, four aft)  24 torpedoes 1 × 3 inch (76 mm)/50 caliber deck gun four machine guns

The United States Navy Salmon-class submarines were an important developmental step in the design of the "fleet submarine" concept during the 1930s. An incremental improvement over the previous Porpoise class, they were the first US submarine class to achieve 21 knots with a reliable propulsion plant, allowing them to operate with the Standard-type battleships of the surface fleet. Also, their 11,000 nautical miles (20,000 km) unrefueled range would allow them to operate in Japanese home waters. These rugged and dependable boats provided yeoman service during World War II, along with their immediate successors, the similar Sargo class. In some references, the Salmons and Sargos are called the "New S Class", 1st and 2nd Groups.

Authorized under the Fiscal Year 1936 provision of the Vinson-Trammell Act, two distinct, but very similar, designs were developed, to be built by three different constructors. The Electric Boat Company of Groton, Connecticut designed and built Salmon, Seal, and Skipjack (SS-182 to 184). The Navy's lead submarine design entity, the Portsmouth Naval Shipyard of Kittery, Maine submitted a design for the Government group, which became Snapper and Stingray (SS-185 & 186). Using the Portsmouth plans and acting as a follow yard, the Mare Island Naval Shipyard of Vallejo, California built Sturgeon (SS-187). The two designs differed in minor details such as the locations of the access hatches for the forward engine room and crew's quarters, the shape of the horizontal conning tower cylinder, and, most significantly, the closure of the main induction valve. This difference led to casualties in Snapper and Sturgeon, and to the loss of Squalus. Larger than the design of the Porpoise-class, the conning tower installed by Electric Boat had two concave spherical ends, The Portsmouth design had a concave end aft and a convex one forward. Portsmouth and Mare Island ran into production difficulties with their conning towers, discovering cracks that caused the cylinder to fail the required pressure test. The problem was successfully fixed, but the experience caused the government yards to adopt the double concave design for the next several years.