HMS Opportune (S20) was an Oberon-class submarine serving with the Royal Navy, notable for its design, operational history, and participation in significant fleet events. The Oberon-class was an evolution of the Porpoise-class, sharing similar dimensions and external design but featuring upgraded equipment, internal fittings, and a higher-grade steel pressure hull for enhanced durability. Constructed by Scotts Shipbuilding and Engineering Company, HMS Opportune was laid down on October 26, 1962, and launched on February 14, 1964. She was officially commissioned into the Royal Navy on December 29, 1964. This submarine measured approximately 241 feet (73 meters) between perpendiculars and 295.2 feet (90 meters) overall, with a beam of 26.5 feet (8.1 meters) and a draught of 18 feet (5.5 meters). Her displacement was 1,610 tons when surfaced and increased to 2,030 tons at full load on the surface, with submerged displacement reaching 2,410 tons. Her propulsion system comprised two Admiralty Standard Range 16 VMS diesel generators and two 3,000 shaft horsepower electric motors, enabling her to reach speeds of up to 17 knots underwater and 12 knots on the surface. HMS Opportune was armed with eight 21-inch torpedo tubes (six forward, two aft), capable of carrying a total of 24 torpedoes. Her sensor suite included Type 186 and Type 187 sonars, along with an I-band surface search radar, supporting her operational versatility. The standard crew numbered 68 personnel, including six officers and 62 sailors. Throughout her service, HMS Opportune was involved in notable incidents, including a minor collision with her sister vessel, HMS Orpheus, in 1967, and a more significant collision with a merchant ship in 1971, which caused damage to her fin and periscopes. She participated in major fleet reviews, notably the 1977 Silver Jubilee Fleet Review off Spithead. Decommissioned on June 2, 1993, she was later scrapped at Pounds scrapyard in Portsmouth. Her legacy is maintained by annual reunions of her crew members, celebrating her service and the lives spent aboard her.

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