The United States Navy Gato class submarine formed the core of the submarine service that was largely responsible for the destruction of the Japanese merchant marine and a large portion of the Imperial Japanese Navy in World War II. Named after the first vessel of this design, USS Gato, the Gato class and its successors, the Balao and Tench classes, formed the majority of the United States Navy's WWII submarine fleet. Gato's name comes from a species of small catshark. Like most other U.S. Navy submarines of the period, the Gato class were given the names of marine creatures.
The Gato-class boats were considered to be "Fleet Submarines". The original rationale behind their design was that they were intended to operate as adjuncts to the main battle fleet. They were to scout out ahead of the fleet and report on the enemy fleet's composition, speed, and course, then they were to attack and whittle down the enemy in preparation for the main fleet action, a titanic gun battle between cruisers and battleships. This was an operational concept borne out of experience from World War I. In order to operate effectively in this role, a submarine had to have high surface speed, long range and endurance, and a heavy armament. State-of-the-art submarine design and construction in the 1920s and 1930s made this combination of qualities very difficult to achieve. The USN constantly experimented with this concept in the post-World War I years, producing a series of submarines with less than stellar qualities and reliability, the T class and the so-called V boats.
By 1931, the experimental phase of fleet submarine development was over and the Navy began to make solid progress towards what would eventually be the Gato class. By 1940, a much better developed industrial base and experience gained from the Porpoise-, Salmon-, & Sargo-class boats resulted in the Tambor & Gar classes. Finally, the USN had hit the right combination of factors and now had the long desired fleet submarine.
Timing, however conspired against the actual use of these boats in their assigned role. The attack on Pearl Harbor on 7 December 1941 destroyed the Pacific Fleet battle line and along with it the concept of the battleship-led gun battle. The successful Pearl Harbor attack overturned 20 years of submarine strategic concept development and left the fleet submarine without a mission. The very same qualities designed into the submarines that enabled them to operate with the fleet made them superbly outfitted for their new mission of commerce raiding against the Japanese Empire.
These boats were authorized in appropriations for Fiscal Year 1941, as part of President Franklin Roosevelt's proclamation of "limited emergency" in September 1939. The first boat laid down was actually the USS Drum at Portsmouth Naval Shipyard on 11 September 1940. She was commissioned on 1 November 1941 and was the only Gato-class boat in commission when the war started. The Gato herself was laid down on 5 October 1940 by the Electric Boat Company at Groton, Connecticut and commissioned 31 December 1941. Due to their large construction capacity, more than half (41) of the class was built at Electric Boat facilities; three new slipways were added to the north yard and four slipways were added to the south yard to accommodate their production. In addition, the government purchased an old foundry downstream from the main yard, constructed ten slipways and turned the yard over to Electric Boat. Called the Victory Yard, it became an integral part of Electric Boat operations. A total of 77 Gatos were built at four different locations (Electric Boat, Manitowoc, Portsmouth, and Mare Island).
There is occasionally some confusion as to the number of Gato-class submarines built with some sources listing the total as 73. This is due to the transitional nature of the first four boats (SS-361 to SS-364) constructed under the second contract by the Manitowoc Shipbuilding Company of Manitowoc, Wisconsin. These were originally intended to be Balao-class subs and were assigned numbers that fall in the middle of the range of numbers for the Balao class (SS-285 to SS-416 & 425-426). Manitowoc was a designated follow-on yard to Electric Boat; they used construction blueprints and plans supplied by Electric Boat and used many of the same suppliers. The government-owned shipyards (Portsmouth Naval Shipyard and Mare Island Naval Shipyard) began to make the transition to the new Balao design in the summer of 1942. Electric Boat, due to the huge backlog of Gato-class construction, was not ready to make the transition to the new design until January 1943. Manitowoc had already completed their allotted production run of Gatos and could not switch over to the Balao design until Electric Boat supplied them with the plans. Faced with a work stoppage while they waited for Electric Boat to catch up, managers at Manitowoc got permission to complete four additional boats (SS-361 to SS-364) to Electric Boat's Gato-class plans. Manitowoc's first Balao-class boat was USS Hardhead.
All of the Gatos (with one exception, USS Dorado) would eventually fight in the Pacific Theater of Operations. However, in the summer of 1942, six brand new Gatos were assigned to Submarine Squadron 50 and sent to Rosneath, Scotland to patrol the Bay of Biscay and to assist in the Operation Torch landings in North Africa. All in all they conducted 27 war patrols but could not claim any verified sinkings. Considered a waste of valuable resources, in mid 1943 all six boats were recalled and transferred to the Pacific.
Once they began to arrive in theater in large numbers in mid-to-late 1942, the Gatos were in the thick of the fight against the Japanese. Many of these boats racked up impressive war records. Flasher, Rasher, and Barb were the top three scoring boats in terms of tonnage sunk by US submarines. Silversides, Flasher, and Wahoo were 3rd, 4th, and 7th place on the list for the number of ships sunk. Gato-class boats sank three Japanese submarines: I-29, I-168 and I-351; while only losing one in exchange, USS Corvina to I-176.
Their principal weapon was the steam powered Mark 14 torpedo in the early war years, with the electric Mark 18 torpedo supplementing the Mark 14 in late 1943. Due to a stunted research and development phase in the Depression era 1930s, and in great part due to the arrogance and stubbornness of the Navy's Bureau of Ordnance, the "wonder weapon" Mark 14 proved to be full of bugs and very unreliable. They tended to run too deep, explode prematurely, run erratically, or fail to detonate. Bowing to pressure from the submariners in the Pacific, the stodgy Bureau eventually acknowledged the problems in the Mark 14 and largely corrected them by late 1943. The Mark 18 electric torpedo was a hastily copied version of captured German G7e weapons and was rushed into service in the fall of 1943. Unfortunately it too was full of faults, the most dangerous being a tendency to run in a circular pattern and come back at the sub that fired it. Once perfected, both types of torpedoes proved to be reliable and deadly weapons, allowing the Gatos and other submarines to sink an enormous amount of Japanese shipping by the end of the war.
The Gatos were subjected to numerous exterior configuration changes during their careers, with most of these changes centered on the conning tower fairwater. The large bulky original configuration proved to be too easy to spot when the boat was surfaced; it needed to be smaller. Secondly, the desire to incorporate new masts for surface and air search radars drove changes to the fairwater and periscope shears. Third, additional gun armament was needed and cutting down the fairwater provided excellent mounting locations for machine guns and anti-aircraft cannon. The modifications (or Mods) to the Gato-class conning tower fairwaters were fairly uniform in nature and they can be grouped together based on what was done when:
- Mod 1 - This is the original configuration with the covered navigation bridge, the high bulwark around the aft "cigarette" deck, and with the periscope shears plated over. All the early boats were built with this Mod and it lasted until about mid 1942.
- Mod 2 - Same as Mod 1 but with the bulwark around the cigarette deck cut down to reduce the silhouette. This also gave the .50 caliber machine gun mounted there a greatly improved arc of fire. Began to appear in about April 1942.
- Mod 3 - Same as Mod 2 but with the covered navigation bridge on the forward part of the fairwater cut away and the plating around the periscope shears removed. In this configuration the Gatos now had two excellent positions for the mounting of more powerful 20 mm anti-aircraft cannon. This mod started to appear in late '42 and early '43.
- Mod 4 - Same as the Mod 3 but with the height of the bridge itself lowered in a last attempt to lessen the silhouette. The lowering of the bridge exposed three I-beams on either side of the periscope shears. These exposed beams gave rise to the nickname "covered wagon boats". Began to appear in early 1944.
A Japanese boarding party from the destroyer Naganami inspected the grounded and abandoned USS Darter (SS-227). Documents disclosed weaknesses, later used to improve Japan's anti-submarine warfare.
In commission: 1943–1969
1,525 tons (1,549 t) surfaced
2,424 tons (2463 t) submerged
Length: 311 ft 8 in (95.00 m) – 311 ft 10 in (95.05 m)
Beam: 27 ft 3 in (8.31 m)
Draft: 17 ft (5.2 m) maximum
4 × diesel engines driving electrical generators (Fairbanks-Morse, General Motors, or Hooven-Owens-Rentschler)
2 × 126-cell Sargo batteries
4 × high-speed electric motors with reduction gears (Elliott Company, General Electric, or Allis-Chalmers)
5,400 shp (4,000 kW) surfaced
2,740 shp (2,040 kW) submerged
21 knots (39 km/h) surfaced
9 knots (17 km/h) submerged
Range: 11,000 nautical miles (20,000 km) surfaced at 10 knots (19 km/h)
48 hours at 2 knots (3.7 km/h) submerged
75 days on patrol
Test depth: 300 ft (90 m)
Complement: 6 officers, 54 enlisted men
10 × 21-inch (533 mm) torpedo tubes (six forward, four aft) 24 torpedoes
1 × 3-inch (76 mm) / 50 caliber deck gun
Bofors 40 mm and Oerlikon 20 mm cannon