Vanguard-class submarine

HMS Vanguard at Faslane, 2010
Class overview
Builders:	Vickers Shipbuilding and Engineering, Barrow-in-Furness, England
Operators:	Royal Navy
Preceded by:	Resolution class
Succeeded by:	Dreadnought class
Cost:	Over £1,500M per boat; Total programme cost £15 billion
In service:	1993–present
Completed:	4
Active:	4
General characteristics
Type:	Nuclear-powered ballistic missile submarine
Displacement:	Submerged: 15,900 t (15,600 long tons; 17,500 short tons)
Length:	149.9 m (491 ft 10 in)
Beam:	12.8 m (42 ft 0 in)
Draught:	12 m (39 ft 4 in)
Propulsion:	1 × Rolls-Royce PWR2 nuclear reactor 2 × GEC turbines; 27,500 shp (20.5 MW) 1 × shaft, pump jet propulsor 2 × auxiliary retractable propulsion motors 2 × WH Allen turbo generators (6 MW) 2 × Paxman diesel alternators; 2,700 shp (2.0 MW)
Speed:	Over 25 knots (46 km/h; 29 mph), submerged
Range:	Unlimited
Complement:	135
Sensors and processing systems:	BAE Systems SMCS Kelvin Hughes Type 1007 I-band navigation radar Thales Underwater Systems Type 2054 composite sonar suite comprising:  Marconi/Ferranti Type 2046 towed array sonar  Type 2043 hull-mounted active and passive search sonar  Type 2082 passive intercept and ranging sonar Pilkington Optronics CK51 search periscope Pilkington Optronics CH91 attack periscope
Electronic warfare & decoys:	Two SSE Mk10 launchers for Type 2066 and Type 2071 torpedo decoys RESM Racal UAP passive intercept
Armament:	4 × 21 in (533 mm) torpedo tubes for: Spearfish heavyweight torpedoes 16 × ballistic missile tubes for: 16 Lockheed Trident II D5 SLBMs (carrying up to 8 warheads each)

The Vanguard class is a class of nuclear-powered ballistic missile submarines (SSBNs) in service with the Royal Navy. The class was introduced in 1994 as part of the Trident nuclear programme, and includes four boats: Vanguard, Victorious, Vigilant and Vengeance. They were built between 1986 and 1999 at Barrow-in-Furness by Vickers Shipbuilding and Engineering, which is now owned by BAE Systems. All four boats are based at HM Naval Base Clyde (HMS Neptune), 40 km (25 mi) west of Glasgow, Scotland.

Since the decommissioning of the Royal Air Force WE.177 free-fall thermonuclear weapons in 1998, the four Vanguard submarines are the sole platforms for the United Kingdom's nuclear weapons. Each submarine is armed with up to 16 UGM-133 Trident II missiles. The class is scheduled to be replaced starting 2028, though its replacement would not enter service until early 2030s.

Beginning in the late 1960s, the United Kingdom operated four Resolution-class submarines, each armed with sixteen US-built UGM-27 Polaris missiles. The Polaris missile was supplied to Britain following the terms of the 1963 Polaris Sales Agreement. This nuclear deterrent system was known as the UK Polaris programme. In the early 1980s the British government began studies examining options for replacing the Resolution-class submarines and its Polaris missiles, both of which would be approaching the end of their service lives within little over a decade. On the 24 January 1980, the House of Commons backed government policy, by 308 votes to 52, to retain an independent nuclear deterrent. Options that were examined included: