Editing Vanguard-class submarine (section)

==Characteristics==
===Weapons and systems===
[[File:Trident II missile image.jpg|thumb|Test launch of a [[Trident missile|Trident II]] missile by a ''Vanguard''-class submarine]]
The ''Vanguard''-class submarines are equipped with 16 ballistic missile tubes. However, as of the [[Strategic Defence and Security Review 2010|2010 Strategic Defence and Security Review]], the Royal Navy loads only eight of the missile tubes with the Trident II submarine-launched ballistic missiles, each armed with up to eight nuclear warheads. In addition to the missile tubes, the submarines are fitted with four 21&nbsp;inch (533&nbsp;mm) [[torpedo tube]]s and carry the [[Spearfish torpedo|Spearfish heavyweight torpedo]],<ref>{{cite web| url=http://www.royal-navy.mod.uk/server/show/nav.2420| author=Royal Naval Website| title=Vanguard Class Ballistic Subs (SSBN)| access-date=18 June 2007| archive-url=https://web.archive.org/web/20070623085113/http://www.royal-navy.mod.uk/server/show/nav.2420| archive-date=23 June 2007| url-status=dead}}</ref> allowing them to engage submerged or surface targets at ranges up to {{convert|65|km|mi nmi}}. Two SSE Mark 10 launchers are also fitted, allowing the boats to deploy Type 2066 and Type 2071 decoys, and a UAP Mark 3 [[electronic support measures]] (ESM) intercept system is carried.

The submarines carry 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 Type 2043 is a hull-mounted active/passive search sonar, the Type 2082 a passive intercept and ranging sonar, and the Type 2046 a [[towed array sonar]] operating at very low frequency providing a passive search capability. The fleet is in the process of having the sonars refitted to include open-architecture processing using [[commercial off-the-shelf]] technology. Navigational search capability is provided by a Type 1007 I-band [[navigation radar]].<ref name="Janes"/> They will also be fitted with the new Common Combat System.<ref>{{cite web|url=https://www.gov.uk/government/news/royal-navys-newest-sub-test-fires-torpedo-using-50-million-uk-made-advanced-combat-system|title=Royal Navy's newest sub test fires torpedo using £50 million UK-made advanced Combat System – News stories – GOV.UK|work=gov.uk|access-date=7 August 2016}}</ref> Two [[periscope]]s are carried, a CK51 search model and a CH91 attack model. Both have TV and [[thermal imaging camera]]s in addition to conventional optics.

A specialised [[Submarine Command System]] (SMCS) was originally developed for the ''Vanguard'' boats and was later used on the {{sclass|Trafalgar|submarine|4}}.<ref>See "The Royal Navy Handbook" 2003, Conway Maritime Press, {{ISBN|0-85177-952-2}}</ref>

===Propulsion===
A new [[pressurized water reactor|pressurised water reactor]], the [[Rolls-Royce plc|Rolls-Royce]] [[Rolls-Royce PWR|PWR 2]], was designed for the ''Vanguard'' class. The PWR 2 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. Furthermore, during their long-overhaul refit periods, a 'Core H' reactor is fitted to each of the boats, ensuring that none of the submarines will require further re-fuelling for the rest of their service lives.<ref name="Janes"/> The reactor drives two [[General Electric Company plc|GEC]] [[steam turbine]]s linked to a single shaft [[pump jet]] propulsor, giving the submarines a maximum submerged speed of over {{convert|25|kn|km/h mph}}. Auxiliary power is provided by a pair of 6&nbsp;MW steam-turbine generators supplied by WH Allen, (later known as NEI Allen, Allen Power & Rolls-Royce), and two 905 kWb [[Paxman (engines)|Paxman]] diesel generators for provision of backup power supply.<ref>{{cite web |url=http://www.paxmanhistory.org.uk/paxsubs.htm |title=Paxman Submarine Engines |author=Richard Carr |publisher=Paxman History Pages |date=19 November 2014 |access-date=24 September 2015 |quote=One engine drives a Brush alternator with a rating of 850 kW. The AC output from this provides auxiliary power for the ship's service (hotel) load. The other Valenta is coupled to a Brush generator with a rating of 750 kW, providing DC output for propulsion in the event of failure or non-availability of the main propulsion system (emergency "get you home").}}</ref>

===Nuclear warheads===
[[British nuclear weapons]] are designed and developed by the UK's [[Atomic Weapons Establishment]]. The boats are capable of deploying with a maximum of 192 independently targetable warheads, or [[Multiple independently targetable reentry vehicle|MIRVs]], with immediate readiness to fire. However, as a result of a decision taken by the [[Strategic Defence Review (1998)|1998 Strategic Defence Review]] this was reduced to 48 warheads with a readiness to fire reduced 'to days rather than minutes'. Furthermore, the total number of warheads maintained by the United Kingdom was reduced to approximately 200, with a total of 58 Trident missiles.  The 2010 [[Strategic Defence and Security Review 2010|Strategic Defence and Security Review]] reduced this number further and the submarines will put to sea in future with a reduced total of 40 warheads and a reduced missile load of 8 (from a maximum possible 16). The number of operationally available nuclear warheads is to be reduced 'from fewer than 160 to no more than 120 and the total UK nuclear weapon stockpile will number no more than 180.<ref>{{cite web|url=http://www.direct.gov.uk/prod_consum_dg/groups/dg_digitalassets/@dg/@en/documents/digitalasset/dg_191634.pdf|title=Securing Britain in an Age of Uncertainty: The Strategic Defence and Security Review|date=19 October 2010|publisher=HM Government|access-date=19 October 2010|archive-url=https://web.archive.org/web/20101222022127/http://www.direct.gov.uk/prod_consum_dg/groups/dg_digitalassets/%40dg/%40en/documents/digitalasset/dg_191634.pdf|archive-date=22 December 2010|url-status=dead}}</ref> The warheads, named  Holbrook, use the Mark 4A aeroshell, and have a yield of 100kt. It is thought to be technically similar to the American [[W76]] warhead, with which it shares its aeroshell and some non-nuclear components.<ref name=":2">{{Cite web |last=Mills |first=Claire |date=1 August 2024 |title=Replacing the UK's nuclear deterrent: The warhead programme |url=https://researchbriefings.files.parliament.uk/documents/CBP-9777/CBP-9777.pdf |website=House of Commons Library}}</ref>

On 16 March 2021 Prime Minister Boris Johnson unveiled his government's 10-year plan to boost international trade and deploy soft power around the world with an aspiration of creating a “Global Britain”. In a document called ''[[Integrated Review|Global Britain in a competitive age]]'', this plan raised the cap on the number of nuclear warheads aboard the Royal Navy's Trident submarines from 180 to 260. The document also vowed to maintain a fleet of four nuclear-armed submarines so Britain would always have one at sea.<ref>{{cite news |url=https://www.msn.com/en-us/news/world/boris-johnsons-vision-for-post-brexit-global-britain-starts-with-more-nuclear-weapons/ar-BB1eEtOo?li=BBnbfcL |title=Boris Johnson's vision for post-Brexit 'Global Britain' includes more nuclear weapons |newspaper=The Washington Post |last=Booth |first=William |date=16 March 2021 |access-date=21 June 2021 |via=msn.com}}</ref> Information of number of deployed warheads and missiles would also no longer be provided following the 2021 Integrated Review, under a policy of "deliberate ambiguity".<ref name=":1">{{Cite web |last=Mills |first=Claire |date=2023-05-03 |title=Nuclear weapons at a glance: United Kingdom |url=https://researchbriefings.files.parliament.uk/documents/CBP-9077/CBP-9077.pdf |url-status=live |archive-url=https://web.archive.org/web/20231227005341/https://researchbriefings.files.parliament.uk/documents/CBP-9077/CBP-9077.pdf |archive-date=2023-12-27 |access-date=2024-01-06 |website=House of Commons Library}}</ref>