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 in length
between perpendiculars and in
length overall, with a beam of , and a draught of . 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 VTS diesel generators, and two electric motors, each driving a 3-bladed propeller at up to 400 rpm. Top speed was when submerged, and on the surface. Eight 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.
Otus was laid down by
Scotts Shipbuilding and Engineering Company on 31 May 1961, and launched on 17 October 1962.
Sea trials were undertaken in Scottish waters, mainly
Loch Long and
Loch Fyne. The boat was commissioned into the Royal Navy on 5 October 1963. ==Operational history==