HMS Onyx (J221) was an Algerine-class minesweeper built for the Royal Navy during the Second World War, notable for its steam turbine propulsion and versatile armament. Displacing approximately 850 long tons at standard load and up to 1,125 long tons at deep load, the vessel measured 225 feet in length overall with a beam of 35 feet 6 inches and a draught of 11 feet. Its propulsion system comprised two Parsons geared steam turbines powered by two Admiralty three-drum boilers, delivering a total of 2,000 indicated horsepower. This machinery enabled a maximum speed of 16.5 knots, with a fuel capacity of 660 long tons of fuel oil, providing an operational range of 5,000 nautical miles at 10 knots. The ship’s design included a complement of 85 officers and ratings. Its armament featured a QF 4-inch Mk V anti-aircraft gun and four twin mounts of Oerlikon 20 mm cannons, although early in its service, shortages meant some ships mounted single Oerlikon guns instead. By 1944, these were gradually replaced by Bofors 40 mm mounts. HMS Onyx was also fitted with four throwers and two rails for depth charges, enhancing its capability in anti-submarine operations. Constructed by Harland & Wolff in Belfast, Northern Ireland, HMS Onyx was ordered on 15 November 1940, laid down on 24 November 1941, launched on 27 October 1942, and commissioned into service on 26 March 1943. Its operational career primarily involved minesweeping duties, contributing to Allied efforts in maintaining safe passageways during the war. After the war, the vessel remained in service until she was placed on the disposal list on 5 April 1967, and subsequently sold to BISCO for scrap, marking the end of her maritime service.

This description has been generated using GPT-4.1-NANO based on the Vessel's wikidata information and then modified by ShipIndex.org staff.