Salmon class submarine
The United States Navy Salmon-class submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

s were an important developmental step in the design of the "Fleet Submarine" concept during the 1930's. An incremental improvement over the previous Porpoise
United States Porpoise class submarine
The Porpoise class were submarines built for the United States Navy in the late 1930s, and incorporated a number of modern features that would make them the basis for subsequent classes such as the Salmon, Tambor, Gato, Balao, and Tench classes...

-class, these rugged and dependable boats provided yeoman service during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, along with their immediate successors, the similar Sargo
Sargo class submarine
The Sargo-class submarines were the first US submarines to be sent into action after the Japanese attack on Pearl Harbor, starting war patrols the day after the attack...



Authorized under the Fiscal Year 1936 provision of the Vinson-Trammel Act, two distinct, but very similar, designs were developed, to be built by three different constructors. The Electric Boat
Electric boat
While a significant majority of water vessels are powered by diesel engines, with sail power and gasoline engines also remaining popular, boats powered by electricity have been used for over 120 years. Electric boats were very popular from the 1880s until the 1920s, when the internal combustion...

 Company of Groton
Groton, Connecticut
Groton is a town located on the Thames River in New London County, Connecticut, United States. The population was 39,907 at the 2000 census....

, Connecticut
Connecticut is a state in the New England region of the northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, and the state of New York to the west and the south .Connecticut is named for the Connecticut River, the major U.S. river that approximately...

 designed and built Salmon
USS Salmon (SS-182)
USS Salmon was the lead ship of her class of submarine. She was the second ship of the United States Navy to be named for the salmon, a soft-finned, gamy fish which inhabits the coasts of America and Europe in northern latitudes and ascends rivers for the purpose of spawning.Her keel was laid down...

, Seal
USS Seal (SS-183)
USS Seal , a Salmon-class submarine, was the second ship of the United States Navy to be named for the seal, a sea mammal valued for its skin and oil. Her keel was laid down on 25 May 1936 by the Electric Boat Company in Groton, Connecticut. She was launched on 25 April 1937 at the Naval Submarine...

, and Skipjack
USS Skipjack (SS-184)
USS Skipjack , a Salmon-class submarine, wasthe second ship of the United States Navy to be named after the fish. Her keel was laid down by the Electric Boat Company in Groton, Connecticut, on 22 July 1936...

 (SS-182 to 184). The Navy's lead submarine design entity, the Portsmouth Naval Shipyard
Portsmouth Naval Shipyard
The Portsmouth Naval Shipyard , often called the Portsmouth Navy Yard, is a United States Navy shipyard located in Kittery on the southern boundary of Maine near the city of Portsmouth, New Hampshire. It is used for remodeling and repairing the Navy's ships...

 of Kittery, Maine
Kittery, Maine
Kittery is a town in York County, Maine, United States. The population was 9,543 at the 2000 census. Home to the Portsmouth Naval Shipyard on Seavey's Island, Kittery includes Badger's Island, the seaside district of Kittery Point, and part of the Isles of Shoals...

 submitted a design for the Government group, which became Snapper
USS Snapper (SS-185)
USS Snapper , a Salmon-class submarine, was the third ship of the United States Navy of the name and the second to be named for the snapper, any of numerous carnivorous, bass-like fishes, esteemed as food and as game fishes. Her keel was laid down by the Portsmouth Navy Yard on 23 July 1936. She...

 and Stingray
USS Stingray (SS-186)
USS Stingray , a Salmon-class submarine, was the second ship of the United States Navy to be named for the stingray, which is a large ray with a whiplike tail and sharp spines capable of inflicting severe wounds. Her keel was laid down by the Portsmouth Navy Yard on 1 October 1936. She was launched...

 (SS-185 & 186). Using the Portsmouth plans and acting as a follow yard, the Mare Island Naval Shipyard
Mare Island Naval Shipyard
The Mare Island Naval Shipyard was the first United States Navy base established on the Pacific Ocean. It is located 25 miles northeast of San Francisco in Vallejo, California. The Napa River goes through the Mare Island Strait and separates the peninsula shipyard from the main portion of the...

 of Vallejo, California
Vallejo, California
Vallejo is the largest city in Solano County, California, United States. The population was 115,942 at the 2010 census. It is located in the San Francisco Bay Area on the northeastern shore of San Pablo Bay...

 built Sturgeon
USS Sturgeon (SS-187)
USS Sturgeon , a Salmon-class submarine, was the second ship of the United States Navy to be named for the sturgeon.Her keel was laid down on October 27, 1936 by the Mare Island Navy Yard. She was launched on March 15, 1938 sponsored by Mrs. Charles S. Freeman; and commissioned on June 25, 1938...

 (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
Conning tower
A conning tower is a raised platform on a ship or submarine, often armored, from which an officer can con the vessel; i.e., give directions to the helmsman. It is usually located as high on the ship as practical, to give the conning team good visibility....

 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
USS Sailfish (SS-192)
USS Sailfish , a , was originally named Squalus.Her keel was laid on 18 October 1937 by the Portsmouth Naval Shipyard in Kittery, Maine, as Squalus, the only ship of the United States Navy named for the squalus. She was launched on 14 September 1938 sponsored by Mrs. Thomas C...

. 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.

Externally, there were minor differences in the shape of the upper edge of the aft end of the conning tower fairwater. The Electric Boat design had a gradual downward taper to this bulwark, the Government design was slightly higher and straighter. Also, as built the Electric Boat trio had two 34 foot periscopes
A periscope is an instrument for observation from a concealed position. In its simplest form it consists of a tube with mirrors at each end set parallel to each other at a 45-degree angle....

. This resulted in a fairly small periscope shear support structure above the fairwater. The three Government boats had one 34 foot and one 40 foot periscope and this necessitated a taller shear and support stanchion
A stanchion is an upright bar or post, often providing support for some other object.* An architectural term applied to the upright iron bars in windows that pass through the eyes of the saddle bars or horizontal irons to steady the leadlight. A stanchion is an upright bar or post, often...


The Electric Boat-built Porpoises had been built to an all-welded
Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, with pressure sometimes...

 design. Conservative engineers and shipfitters at the Government yards stuck with tried and true riveting. Electric Boat's method proved superior, providing a stronger and tighter boat, as well as preventing leakage of fuel oil tanks after depth charge
Depth charge
A depth charge is an anti-submarine warfare weapon intended to destroy or cripple a target submarine by the shock of exploding near it. Most use explosives and a fuze set to go off at a preselected depth in the ocean. Depth charges can be dropped by either surface ships, patrol aircraft, or from...

 attacks. Finally convinced of the efficacy of Electric Boat's innovation, Government yards finally converted wholesale to welding for their three Salmons and the Navy was entirely happy with the results.

The six boats of this class were straight forward derivations of the later boats of the preceding Porpoise class. Although considered to be successful in most respects, valuable lessons had been learned from the Porpoises and operating experience showed the need to expand the operating envelope. The Salmons were longer, heavier, and faster versions with a better internal arrangement and a heavier armament. Two additional torpedo tube
Torpedo tube
A torpedo tube is a device for launching torpedoes. There are two main types of torpedo tube: underwater tubes fitted to submarines and some surface ships, and deck-mounted units installed aboard surface vessels...

s were added to the aft torpedo room, for a total of four forward and four aft. Some submariners wanted six tubes forward, but design philosophy and tactics of the day did not yet support this. However, in an effort to increase the number of torpedoes carried, four non-firing torpedo stowage tubes were installed in the superstructure below the main deck, stacked vertically, two each on either side of the conning tower. In order to access the weapons in these tubes, the boat had to surface and remove a portion of the decking on either side of the deck gun. Small boats stowed there for running sailors ashore for liberty were removed and set in the water. The weapons were extracted from the tubes one by one and winched up to the main deck. They were then placed on a raised loading skid and carefully lowered on an angle through a hatch into the forward torpedo room. This whole process took several hours to complete. The impracticality of spending several hours on the surface in enemy waters moving torpedoes below was lost on the designers. War experience led to the removal of these tubes during the boats' first wartime overhauls.

Two different main (diesel
Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...

) engine types were installed in these boats during construction. The Government boats received a new model GM-Winton 16-248 V16. Steady development work by GM-Winton had largely corrected earlier problems and this engine proved to be fairly reliable and rugged. The three Electric Boat units received a nine-cylinder version of the Hooven-Owens-Rentschler
The firm of Hooven, Owens, Rentschler, and Company manufactured steam and diesel engines in Hamilton, Ohio. Because the firm was frequently known by its initials, H.O.R., the Hooven is sometimes incorrectly rendered as Hoover, and the Owens may be mistaken for Owen.The firm was the successor to the...

 (HOR) double acting engine. This was based on a successful steam engine design. Having a power stroke in both directions of the piston, this engine promised nearly twice the horsepower in a size similar to a conventional in-line or V-type engine. Unfortunately, HOR encountered severe design and manufacturing difficulties converting the concept to internal combustion. They vibrated excessively due to imbalances in the combustion chambers. This broke engine mounts and caused difficulties in the drive train. Improper manufacturing of the gearing resulted in broken gear teeth. Reluctant to give up on the promise of the engine, the Navy coddled the HORs along until after the Pacific War
Pacific War
The Pacific War, also sometimes called the Asia-Pacific War refers broadly to the parts of World War II that took place in the Pacific Ocean, its islands, and in East Asia, then called the Far East...

 began, when increased funding and operational needs caused these engines to be replaced with GM-Winton 16-278As during the boat's first wartime overhauls.

Serious problems were encountered with the Porpoise-class all-electric drive. This drove the decision to radically alter the propulsion plant. The Salmons were fitted with the so-called "composite drive". In this arrangement, two main engines in the forward engine room drove generators in the fashion set by the Porpoises. In the after engine room, two side-by-side engines were clutched to reduction gears which sat forward of the engines. The propeller shafts led aft from from each of the reduction gears, and were sited outboard of the engines. Two electric motors were mounted outboard of each shaft, connected directly to the reduction gears. For surfaced operation the engines were clutched in to the reduction gears and drove the propellers directly, with the generator engines providing additional voltage to the motors. For submerged operation, the direct drive engines were declutched from the reduction gears and the motors drove the shafts with electricity supplied by the batteries. Although proven to be satisfactory in operation, this unusual arrangement was quite cramped, making maintenance and repairs in the aft engine room somewhat difficult.

All six of these submarines (and all subsequent U.S. Navy submarines up to the late 1940s) were built to a "partial-double hull" design. In this hull type, the inner pressure resisting hull is wrapped by an outer hydrodynamically smooth hull. The space between these two hulls is used for ballast and fuel tanks. The outer hull smoothly tapers into the pressure hull in the area of the forward and after torpedo room bulkheads, leaving the pressure hull exposed at the extreme ends of the boat. This is actually an advantage as it allows access to the pressure hull in these areas for maintenance. In a full double hull boat, the outer hull completely encompasses the pressure hull and the very narrow ends make it very hard to reach the pressure hull for repairs and maintenance.

Commissioning and pre-war service

Portsmouth proved to be quite efficient in their production methods and they managed to complete and commission both Snapper and Stingray before Electric Boat delivered the lead boat Salmon for commissioning. In fact, all three of the Government built boats of this class beat their commercially built counterparts into service.

After commissioning, these boats were very active in the fleet, operating initially with the Atlantic Fleet, conducting exercises in the Caribbean
Caribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....

 and around both sides of the Panama Canal
Panama Canal
The Panama Canal is a ship canal in Panama that joins the Atlantic Ocean and the Pacific Ocean and is a key conduit for international maritime trade. Built from 1904 to 1914, the canal has seen annual traffic rise from about 1,000 ships early on to 14,702 vessels measuring a total of 309.6...

. They transferred to the Pacific Fleet
United States Pacific Fleet
The United States Pacific Fleet is a Pacific Ocean theater-level component command of the United States Navy that provides naval resources under the operational control of the United States Pacific Command. Its home port is at Pearl Harbor Naval Base, Hawaii. It is commanded by Admiral Patrick M...

 in late 1939, homeported out of San Diego, commanded by COMSUBPAC
Commander Submarine Force, U.S. Pacific Fleet is the principal advisor to the Commander, United States Pacific Fleet for submarine matters. The Pacific Submarine Force includes attack, ballistic missile and auxiliary submarines, submarine tenders, floating submarine docks, deep submergence...

 Admiral Wilhelm L. Friedell. In October 1941, as war clouds loomed on the horizon, the Salmons were all transferred to the Asiatic Fleet as part of a belated effort to reinforce U.S. and Allied forces in the Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...

. They operated out of Cavite in Manila Bay
Manila Bay
Manila Bay is a natural harbor which serves the Port of Manila , in the Philippines.The bay is considered to be one of the best natural harbors in Southeast Asia and one of the finest in the world...

 until the war commenced.

World War II

From the very start, the Salmons were in the thick of the fight in the defense of the Philippines. The submarines of the Asiatic Fleet were the primary striking force available to Admiral
Admiral is the rank, or part of the name of the ranks, of the highest naval officers. It is usually considered a full admiral and above vice admiral and below admiral of the fleet . It is usually abbreviated to "Adm" or "ADM"...

 Thomas C. Hart
Thomas C. Hart
Thomas Charles Hart was an admiral of the United States Navy, whose service extended from the Spanish-American War through World War II. Following his retirement from the Navy, he served briefly as a United States Senator from Connecticut.-Life and career:Hart was born in Genesee County, Michigan...

, the fleet's commander. He was assigned twelve Salmons or Sargos: Sailfish, Salmon, Sargo, Saury, Sculpin, Seal, Skipjack, Snapper, Stingray, Sturgeon, Swordfish.

The qualities designed into the Salmons for their role as fleet submarines made them well suited for the war they found themselves fighting, but some shortcomings came up that were not apparent prior to the war. It came to be realized that the boats were going to spend a lot more time on the surface than what had been previously acknowledged. Thus the large bulk of the conning tower fairwater became a liability. It was too easily spotted by keen-eyed Japanese lookouts using their excellent binoculars
Binoculars, field glasses or binocular telescopes are a pair of identical or mirror-symmetrical telescopes mounted side-by-side and aligned to point accurately in the same direction, allowing the viewer to use both eyes when viewing distant objects...

. It was found that portions of the fairwater plating could be cut away both fore and aft of the bridge, greatly reducing the silhouette. This also had the desirable effect of creating mounting locations for 20mm rapid fire cannon
Oerlikon 20 mm cannon
The Oerlikon 20 mm cannon is a series of autocannons, based on an original design by Reinhold Becker of Germany, very early in World War I, and widely produced by Oerlikon Contraves and others...

, which were useful against aircraft and small surface targets.

The timely development of radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

 in the USN proved to be a key factor in the eventual victory over the Imperial Japanese Navy
Imperial Japanese Navy
The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...

, and its incorporation into the Salmons and other USN submarines gave them a critical advantage in detection and defense. The first sets became available within days of the war beginning, and they were introduced to the boats as they went into overhaul in 1942.

The original Mk. 21 3"/50 caliber deck gun proved to be too light in service. It lacked sufficient punch to finish off crippled or small targets quickly enough to suit the crews. It was replaced by the Mk. 9 4"/50 caliber gun in 1943 and 1944.

The well liked Salmons were heavily relied on by the Submarine Force during the first two and a half years of the war, with some of them completing 15 war patrols before being assigned to training duties by 1945.

A few highlights

  • Salmon
    USS Salmon (SS-182)
    USS Salmon was the lead ship of her class of submarine. She was the second ship of the United States Navy to be named for the salmon, a soft-finned, gamy fish which inhabits the coasts of America and Europe in northern latitudes and ascends rivers for the purpose of spawning.Her keel was laid down...

    barely survived a severe depth charging by Japanese escort ships on 30 October 1944. She was retired from combat duty and spent the rest of the war as a training boat.
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