HMS Churchill (S46)

In 1965, following a decision by the Labour government not to build a fifth ballistic missile submarine, production of nuclear-powered fleet submarines, which had been postponed owing to the priority given to the Polaris programme, could be restarted. Churchill, the Royal Navy's fourth nuclear-powered fleet submarine was ordered on 21 October 1965, and was laid down at Vickers Shipbuilding and Engineering Limited (VSEL)'s Barrow-in-Furness shipyard on 30 June 1967. Following a collision between sister submarine and a Soviet Echo II-class submarine in the Barents Sea on 9 October 1968, the fin of Churchill, still under construction at Barrow, was used to replace Warspites fin, which had been badly damaged in the collision. Churchill was launched by Mary Soames, Winston Churchill's youngest daughter, on 20 December 1968, and commissioned on 15 July 1970. ==Propulsion==

Churchill was chosen to trial the first full-size submarine pump jet propulsion. Trials of a high-speed unit were followed by further trials with a low-speed unit, and these were successful enough for the same propulsion to be fitted in the rest of the class. Later British submarine classes also featured the pump jet, although first-of-class vessels Swiftsure and Trafalgar were fitted with propellers at build. ==Notes==