HMS Cachalot (S06)

HMS Cachalot (S06) was a Porpoise-class submarine. Her keel was laid down on 1 August 1955 by Scotts Shipbuilding and Engineering Company at Greenock. She was launched on 11 December 1957, and commissioned on 1 September 1959.

Design
The Porpoise class was the first class of operational submarines built for the Royal Navy after the end of the Second World War, and were designed to take advantage of experience gained by studying German Type XXI U-boats and British wartime experiments with the submarine HMS Seraph (P219), which was modified by streamlining and fitting a bigger battery.

The Porpoise-class submarines were 290 ft long overall and 241 ft between perpendiculars, with a beam of 26 ft and a draught of 18 ft. Displacement was 1565 LT standard and 1975 LT full load surfaced and 2303 LT submerged. Propulsion machinery consisted of two Admiralty Standard Range diesel generators rated at a total of 3680 bhp, which could charge the submarine's batteries or directly drive the electric motors. These were rated at 6000 shp, and drove two shafts, giving a speed of 12 kn on the surface and 16 kn submerged. Eight 21 in torpedo tubes were fitted; six in the bow, and two in the stern. Up to 30 torpedoes could be carried, with the initial outfit consisting of the unguided Mark 8 and the homing Mark 20 torpedoes.

Service
Cachalot attended the 1977 Silver Jubilee Fleet Review off Spithead when she was part of the Submarine Flotilla.

She was sold on 12 November 1979 for breaking up at Blyth.