Amphion class submarine

HMS Alliance at Gosport submarine museum
Class overview
Builders:	Vickers Armstrong, Barrow-in-Furness Cammell Laird, Birkenhead Scotts of Greenock HM Dockyard, Chatham
Operators:	Royal Navy
Preceded by:	V class
Succeeded by:	Explorer class
In service:	1945 - 1974
Completed:	46 planned, 16 commissioned
Preserved:	1
General characteristics
Type:	Submarine
Displacement:	1,385 tons surfaced, 1,620 tons submerged
Length:	280.5 ft (85.5 m)
Beam:	22.3 ft (6.8 m)
Draught:	16.8 ft (5.1 m)
Speed:	18.5 knots (34.3 km/h) surfaced 8 knots (15 km/h) submerged
Range:	10,500 nautical miles (19,400 km) at 11 knots (20 km/h) surfaced 16 nautical miles (30 km) at 8 knots (15 km/h) submerged
Test depth:	500 feet (150 m)
Complement:	61 officers and men
Armament:	6 × 21 in (533 mm) bow torpedo tubes (2 external, one-shot, later removed) 4 × 21 in (533 mm) stern torpedo tubes (2 external, one-shot, later removed) 16 torpedoes or 26 mines carried internally 1 × QF 4 in (102 mm) gun (Mk XXII or Mk XXIII) 1 × one Oerlikon 20 mm cannon 3 × .303-caliber machine guns

The Amphion class (also known as the "A" class and Acheron class) of British diesel-electric submarines were designed for use in the Pacific War. Only two were completed before the end of hostilities, but following modernisation in the 1950s, they continued to serve in the Royal Navy into the 1970s.

The Amphion class were ordered by the British Admiralty in 1943, upon the realisation that the new Pacific theatre of war following the attack on Pearl Harbor needed a new type of submarine. They were originally designed to replace the S-class and T-class submarines, which were too slow and unable to dive deep enough to be suited to Pacific waters during World War II. They were an enlargement of the T class, arranged for fast, simple construction and to utilize much of the materials and equipment set aside for the T boats. They had a high, flared bow for excellent sea performance and had effective air conditioning, essential for Far East submarine operations. They were operated by a crew of between 60 and 68.

Originally, 46 submarines were ordered, but only 18 were launched (10 by Vickers-Armstrong in Barrow-in-Furness) and 16 commissioned, the other two hulls being used for crush testing. The class was designed for quick construction, using an entirely welded hull which could be fabricated in sections, a technique new to Britain but standard for Nazi Germany's U-boats. Each submarine took about 8 months from keel-laying to launching, compared with around 15 months for the earlier T class, but only two of the boats were completed before the end of the war: Amphion, launched in August 1944, and Astute in January 1945; neither saw action.