The Barracuda-class submarines (originally the K-1-class submarines) were the product of Project Kayo, a research and development effort begun immediately after World War II by the United States Navy to "solve the problem of using submarines to attack and destroy enemy submarines." They originally had the hull classification symbol SSK, for "hunter-killer submarine". These submarines were originally named K-1 through K-3, with hull numbers SSK-1 through SSK-3. They were renamed Barracuda, Bass, and Bonita in December 1955. In 1959 Barracuda was redesignated SST-3 (SST for training submarine), and in 1964 her main sonar was removed. A final redesignation twist was SS-T3 in 1973; for some reason the Navy wished to list her as an attack submarine. Bass was decommissioned in 1957 and redesignated SS-551 in 1959. Bonita was decommissioned in 1958 and redesignated SS-552 in 1959. Background It was known that the Soviet Navy had acquired the German Type XXI U-boat and other advanced submarines, and was expected to rapidly put derivatives of them into production. In 1948 the US Navy prepared estimates of the number of anti-submarine warfare (ASW)-capable submarines (SSKs) that would be needed to counter the hundreds of advanced Soviet submarines that were expected to be in service by 1960. Two scenarios were considered: a reasonable scenario assuming the Soviets would build to their existing force level of about 360 submarines, and a "nightmare" scenario projecting that the Soviets could build submarines as fast as the Germans had built U-boats, with a force level of 2,000 submarines. The projected US SSK force levels for these scenarios were 250 for the former and 970 for the latter. By comparison, the total US submarine force at the end of World War II, excluding obsolescent training submarines, was just over 200 boats. Design The Barracuda-class SSKs were designed to be smaller than contemporary attack submarines and simpler in design and construction. It was hoped that this would allow them to be cheaply mass-produced in the large numbers it was thought would be needed to combat the growing Soviet Type XXI-derived submarine fleet. It was also thought that this would allow shipyards without submarine experience, and aircraft contractors with experience in the mass production of large complex aircraft, to build these submarines. The primary innovation created by Kayo was a low-frequency passive bow sonar system, the BQR-4, which was originally to be wrapped around the submarine's conning tower. Testing on showed