Vanguard-class submarine

The Vanguard class are the Royal Navy's current nuclear ballistic missile submarines (SSBN), each armed with 16 Trident II SLBMs.

The class includes four boats: Vanguard (S28), Victorious (S29), Vigilant (S30), and Vengeance (S31), all built at Barrow-in-Furness by Vickers Shipbuilding and Engineering Ltd between 1986 and 1999.

All four boats are based at Her Majesty's Naval Base Clyde, 25 miles (40 km) west of Glasgow, Scotland. Since the decommissioning of free-fall nuclear bombs in 1998, the Vanguard submarines' Trident ICBM system is the UK's only nuclear deterrent.

Template:Infobox Class

Design

The Vanguards were designed from the outset as an unlimited-range nuclear powered ballistic missile submarine, unlike the previous Resolution-class which was adapted from the then existing Valiant class of nuclear powered fleet submarines (SSN in US terms). At more than 150 metres long and 16,000 tons submerged displacement the Vanguards are roughly twice the size of the Resolutions, and are the third largest submarines ever built, by displacement when surfaced, after the Russian Typhoon and American Ohio classes. The great increase in size is largely related to much larger size of the Trident D-5 missile as compared to Polaris.

The Vanguards were designed and built at Barrow-in-Furness by Vickers Shipbuilding and Engineering Limited (VSEL), now BAE Systems Submarines. The Devonshire dock hall was built specifically to build these submarines. The missile compartment is based on the system used on the Ohio class, though only 16 missiles are carried rather than the 24 of the Ohio.

In addition to the missile tubes the Vanguard class is fitted with four 21 inch (53.3 cm) torpedo tubes and carries the Spearfish heavyweight torpedo, allowing it to engage submerged or surface targets at ranges up to 65 kilometres (40 miles). Two SSE Mark 10 launchers are also fitted to allow the boats to deploy Type 2066 and Type 2071 decoys, and a UAP Mark 3 electronic support measures (ESM) intercept system is fitted.

HMS Vanguard, Victorious, Vigilant and Vengeance were commissioned in 1993, 1995, 1996 and 1999 respectively.

Sensors

Vanguard carries the Thales Underwater Systems Type 2054 composite sonar. The Type 2054 is a multi-mode, multi-frequency system, which incorporates the 2046, 2043 and 2082 sonars. The fleet is in the process of having their sonars refitted to include open architecture processing using commercial off the shelf technology.

A Type 2043 hull-mounted active/passive search sonar is also carried, as is a Type 2082 passive intercept and ranging sonar. Finally a Type 2046 towed array is carried. This operates at very low frequency, giving a passive search capability.

Two periscopes are carried, a CK51 search model and a CH91 attack model. Both have a TV camera and thermal imager as well as conventional optics.

A Type 1007 I-band navigation radar is also carried.

Command System

A specialised Submarine Command System (SMCS) was originally developed for the Vanguard boats and was later used on other Royal Navy submarines.

Propulsion

A new pressurised water reactor, the PWR 2, was designed for the Vanguard class. This has double the service life of previous models, and it is estimated that a Vanguard class submarine could circumnavigate the world 40 times without refuelling. This should allow the class to carry out their entire service life without the need for expensive refuelling. The reactor drives two GEC turbines linked to a single shaft pump jet propulsor. This propulsion system gives the Vanguards a maximum submerged speed of 25 knots. There are two Paxman diesel alternators and two turbo generators from WH Allen.

Cost

The total acquisition costs of the Trident programme are £12.57 billion (at 1996-97 prices), which is over £3.6 billion lower in real terms than the original 1982 estimate. Government estimates put the cost of the entire Trident program at approximately £200 million per year over a 30 year in-service life. This estimate includes manpower, stores, refits, transport, shore facilities, decommissioning and disposal costs plus some of the expense of the Atomic Weapons Establishment. Using this figure of £200 million, and the figure for the UK's total defence spending for the year 2005-2006 of $51.1 billion, or £29.6 billion the annual current cost of the Trident force with all the shore-based facilities referred to above amounts to a mere 0.7% of total annual defence spending. This does not however take into account the acquisition costs of Trident, which would increase the proportion to around 2% of defence spending over the lifetime.

UK nuclear policy

The principle of operation is based on maintaining deterrent effect by always having at least one submarine at sea, and was designed for the Cold War period. One submarine is normally undergoing maintenance and the remaining two are in port or on training exercises. The Bulletin of the Atomic Scientists claims that UK SSBN patrols may be co-ordinated with the French [1] - this assertion has not been repeated elsewhere and is widely believed to be false. The missiles were "detargeted" in 1994 in time for the maiden voyage of the first Vanguard class SSBN[2].

Each submarine carries 16 Trident II D-5 missiles, which can each carry up to twelve warheads (i.e. a potential of 192 warheads). However, the British government announced in 1998 that each submarine would carry only 48 warheads (halving the limit specified by the previous government), which is an average of three per missile, an increase of 50% over Trident's predecessor, Polaris A3TK Chevaline. However one or two missiles per submarine may be armed with fewer warheads for "sub-strategic" use causing others to be armed with more, but there is no hard evidence to support this speculation.

The British-manufactured warheads are thought to be selectable between 0.3 kt, 5-10 kt and 100 kt; the yields obtained using either the unboosted primary, the boosted primary, or the entire thermonuclear warhead but there is no hard evidence from official sources to support this speculation. There is some tenuous evidence that the warhead design is similar, or even based on the US W76 warhead fitted in some US Navy Trident missiles, with design data being supplied by the United States through the 1958 US-UK Mutual Defence Agreement. The United Kingdom has purchased the rights to 58 missiles under the Polaris Sales Agreement (modified for Trident) from a jointly maintained "pool". These missiles are fitted with UK-built warheads and are exchanged when requiring maintenance. Under the terms of the agreement the United States does not have any veto on the use of British nuclear weapons. [3]

History

Table 1 Vanguard class—significant dates

Name	Launched	Commissioned	Test launch 1	Test launch 2	Maiden patrol
HMS Vanguard (S28)	March 1992	August 1993	May 26, 1994	June 20, 1994	December 1994
HMS Victorious (S29)	September 1993	January 1995	July 24, 1995	August 22, 1995	December 1995
HMS Vigilant (S30)	October 1995	November 1996	October 10, 1997	October 10, 1997	June 1998
HMS Vengeance (S31)	September 1998	November 1999	September 21, 2000		February 2001

The Trident missile agreement was reached in 1982 as a modification of the Polaris Sales Agreement. At the time it was envisaged the entire project; four submarines, the missiles, new facilities at Coulport and Faslane and a 5% contribution to Trident research and development, would cost £5 billion. The option for a fifth submarine was discussed at the time.

The submarines were built in specially constructed facilities at Vickers Shipbuilding and Engineering Ltd, subsequently GEC Marine (VSEL) and BAE Systems Marine (VSEL), Barrow-in-Furness, Cumbria. The Trident II D-5 achieved an initial operational capability with the U.S. Navy in March 1990. Following launch and commissioning the vessels deployed on Demonstration and Shakedown Operations (DASOs). The major part of this was the test firing of Trident missiles at the United States' SLBM Launch Area, Eastern Test Range, Cape Canaveral, off the coast of Florida (see table above).

Number of warheads

Test launch of a Trident D5 SLBM

In the Strategic Defence Review published in July 1998, the British Government stated that once the Vanguard submarines became fully operational (the fourth and final one, Vengeance, entered service on 27 November 1999), it would "maintain a stockpile of fewer than 200 operationally available warheads" [4]. The Stockholm International Peace Research Institute has estimated the figure as about 165, consisting of 144 deployed weapons plus an extra 15% as spares Spares are usually needed within the supply chain, including the maintenance workshops.

At the same time, the British Government indicated that warheads "required to provide a necessary processing margin and for technical surveillance purposes" were not included in the "fewer than 200" figure [5]. However, as recently declassified archived documents on Chevaline make clear, the 15% excess (referred to by SIPRI as for spares) is normally intended to 'provide the necessary processing margin' and 'surveillance rounds do not contain any nuclear material' being completely inert. These surveillance rounds are used to monitor deterioration in the many non-nuclear components of the warhead, and are best compared with inert training rounds. The SIPRI figures correspond accurately with the official announcements and are likely to be the most accurate. The Natural Resources Defense Council speculates that a figure of 200 is accurate to within a few tens, and the World Almanac speculates that the number is between 200 and 300, but fails to produce any hard evidence. Experience with earlier weapons has demonstrated that it is dangerous to speculate in this area, and the speculation has invariably been proved wrong.

General characteristics

• Displacement: 15,900 tons submerged
• Length: 149.9 meters
• Beam: 12.8 meters
• Draught: 12 meters
• Complement: 14 officers, 121 ratings
• Propulsion: PWR2 reactor
• Armament:
  • 16 missile tubes capable of firing Trident II (D5) missiles
  • four 21 inch (533 mm) torpedo tubes capable of firing Spearfish or other 21 inch torpedoes.
• Sensors:
  • sonar (bow array, active intercept, and towed arrays)
  • periscopes: (attack and two search periscopes)
  • collision avoidance radar
• Command System:
  • SMCS at introduction of service
  • SMCS-NG from 2006 onwards

See also

• Nuclear weapons and the United Kingdom
• United Kingdom and weapons of mass destruction

External links

• The Royal Navy's official page on the Vanguard Class.
• Information page on the Vanguard Class.
• Naval technology page on the Vanguard class.
• HMS Vanguard Trident II test-launch - YouTube video