HMS Affray (P421)

Submarine of the Royal Navy

HMS Affray was a British Amphion class submarine. It was the last Royal Navy submarine to be lost at sea, on 16 April 1951, with the loss of 75 lives. Affray was built in the closing stages of the Second World War. She was one of 16 submarines of her class which were originally designed for use in the Pacific Ocean against Japan.

She was laid down at the Cammell Laird yard in Birkenhead on 16 January 1944, launched on 12 April and commissioned on 25 November 1945. Affray and her sisters were state of the art submarines at the time of their launching. They were the culmination of a rapid submarine development driven by the Second World War. Some elements of her design were taken from captured Nazi German U boats. Her modular style of manufacture and all welded hull were unique at the time. For work in the Far East she was equipped with refrigeration and two huge air conditioners, and all her accommodation was placed as far away from the engine room as possible. She also had ten torpedo tubes which made her and her class some of the most formidable submarines in the world at that time. She was sent to the submarine tender HMS Montclare at Rothesay, as part of the 3rd Submarine Flotilla, before joining her sisters HMS Amphion, Astute, Auriga, Aurochs and the submarine tender HMS Adamant in the British Pacific Fleet. The following four years Affray was on travel and took part in exercises all over the globe, visiting such places as Australia, Singapore, Japan, Morocco, South Africa, Pearl Harbor and Bergen.

On 11 March 1949 she was transferred to the 5th Submarine Flotilla reserve and entered drydock to be retrofitted with a snort mast (snorkel device)—a pneumatically raised and lowered steel tube which, when in the vertical position, worked as an air induction/exhaust emission device. Once vertical it was self locking and drew air into the submarine at periscope depth, permitting the submarine to charge batteries and run diesels for propulsion below the surface, allowing the sub to remain underwater. At the point where the air intake entered the pressure hull of the submarine, there was a bulbous casting—set about half a metre above the hull, this housed the main induction valve. This very important casting was totally concealed and protected by the free flooding hull. The snort mast on the Affray was designed for both air intake and exhaust venting; this was later changed so the snort mast was an air intake only and the exhaust was moved to the rear of the conning tower. The snort mast had a float valve that would close automatically if the submarine dropped below periscope depth. In December of that same year Affray was sent to the Mediterranean; it was recorded during deep dives in this sea that she began "leaking like a sieve" and that the Admiralty class diesels started leaking oil. In January 1951 Affray was transferred to Portsmouth Naval base to join Reserve group "G". In March she was brought out of reserve, and Lieutenant John Blackburn DSC was appointed CO and given the task of bringing her and the new crew up to operational status.