HMS Onyx (J221)

HMS Onyx (J221) was a steam turbine-powered Algerine-class minesweeper during the Second World War.

Design and description
The turbine-powered ships displaced 850 LT at standard load and 1125 LT at deep load. The ships measured 225 ft long overall with a beam of 35 ft. The turbine group had a draught of 11 ft. The ships' complement consisted of 85 officers and ratings.

The ships had two Parsons geared steam turbines, each driving one shaft, using steam provided by two Admiralty three-drum boilers. The engines produced a total of 2000 ihp and gave a maximum speed of 16.5 kn. They carried a maximum of 660 LT of fuel oil that gave them a range of 5000 nmi at 10 kn.

The Algerine class was armed with a QF 4 in Mk V anti-aircraft gun and four twin-gun mounts for Oerlikon 20 mm cannon. The latter guns were in short supply when the first ships were being completed and they often got a proportion of single mounts. By 1944, single-barrel Bofors 40 mm mounts began replacing the twin 20 mm mounts on a one for one basis. All of the ships were fitted for four throwers and two rails for depth charges.

Construction and career
The ship was ordered on 15 November 1940 at the Harland & Wolff at Belfast, Northern Ireland. She was laid down on 24 November 1941 and launched on 27 October 1942. The ship was commissioned on 26 March 1943.

On 5 April 1967, she was put on the disposal list and sold to BISCO for scrap.