HMS Otter (S15)

HMS Otter (S15) was an Oberon-class submarine submarine of the Royal Navy.

Design and construction
The Oberon class was a direct follow on of the Porpoise-class, with the same dimensions and external design, but updates to equipment and internal fittings, and a higher grade of steel used for fabrication of the pressure hull.

As designed for British service, the Oberon-class submarines were 241 ft in length between perpendiculars and 295.2 ft in length overall, with a beam of 26.5 ft, and a draught of 18 ft. Displacement was 1,610 tons standard, 2,030 tons full load when surfaced, and 2,410 tons full load when submerged. Propulsion machinery consisted of 2 Admiralty Standard Range 16 VMS diesel generators, and two 3,000 shp electric motors, each driving a 7 ft 3-bladed propeller at up to 400 rpm. Top speed was 17 kn when submerged, and 12 kn on the surface. Eight 21 in diameter torpedo tubes were fitted (six facing forward, two aft), with a total payload of 24 torpedoes. The boats were fitted with Type 186 and Type 187 sonars, and an I-band surface search radar. The standard complement was 68: 6 officers, 62 sailors.

Otter was laid down by Scotts Shipbuilding and Engineering Company on 14 January 1960, and launched on 15 May 1961. The boat was commissioned into the Royal Navy on 20 August 1962. The only Oberon class submarine fitted with a mild steel casing needed when deployed as target for practice torpedo attacks.

Decommissioning and fate
Otter was paid off on 31 July 1991.