Military Wiki
Astute-class submarine
HMS Ambush.jpg
HMS Ambush on sea trials in December 2012
Class overview
Builders: BAE Systems Submarine Solutions
Royal Navy Jack
Royal Navy
Preceded by: Trafalgar class
Cost: £1,160M each (boats 1-3), £747M each (boats 4-6)[1]
Built: 2001–present
In commission: 2010–present
Building: 7
Planned: 7
Completed: 4
Active: 4
General characteristics
Class & type: Nuclear-powered fleet submarine
Displacement: 7,000 tonnes, surfaced
7,400 tonnes, submerged[2]
Length: 97 m (318 ft)
Beam: 11.3 m (37 ft)
Draught: 10 m (33 ft)
Propulsion: Rolls-Royce PWR 2 reactor, MTU 600 kilowatt diesel generators
Speed: Up to 30 knots (56 km/h), submerged[3]
Range: Only limited by food and maintenance requirements.
Test depth: Over 300 m
Complement: 98 (capacity for 109)
Sensors and
processing systems:

6 × 21-inch (533 mm) torpedo tubes with stowage for up to 38 weapons:[4]

The Astute class is the latest class of nuclear-powered fleet submarines in service with the British Royal Navy. The class sets a new standard for the Royal Navy in terms of weapons load, communication facilities and stealth. The boats are being constructed by BAE Systems Submarine Solutions at Barrow-in-Furness.[5] Seven boats will be constructed. The first of class, Astute, was launched in 2007 and commissioned in 2010, and the second, Ambush, was launched on 6 January 2011,[6] and commissioned on 1 March 2013.[7]


The Royal Navy has changed its submarine-employment strategy from the Cold War emphasis on anti-submarine warfare to the concept of "Maritime Contributions to Joint Operations." [8] Approval for studies to define the "Batch 2 Trafalgar class" (what would become the Astute class) was given in June 1991. In July 1994 risk reduction studies were authorised in parallel with the formal bid phase of the project.[9] On 17 March 1997, the Ministry of Defence announced that it would place a £2 billion order for three submarines and that they would be called the Astute class. On 26 March 1997 the contract was signed with GEC-Marconi for the first three boats: Astute, Ambush and Artful. These names were last given to Amphion-class submarines that entered service towards the end of World War II. GEC would build the submarines at its VSEL subsidiary (now BAE Systems Submarine Solutions).

Original plans were for seven boats of the Astute class to replace five Swiftsure-class submarines (Sovereign, Superb, Sceptre, Spartan, and Splendid) and the two oldest Trafalgar-class boats (Trafalgar and Turbulent). The Swiftsure class entered service between 1973 and 1977 and were entirely decommissioned by 2010, when only the first of the Astute class was coming into service. Trafalgar was decommissioned in December 2009, to be followed by Turbulent in 2011.[10] An estimated 5,900 people are employed directly as a result of the project; 3,500 BAE Systems staff at Barrow and 2,400 other people around the UK.[11]

As of August 2006 BAE Systems was negotiating for a contract to build another four Astute-class submarines (hulls four to seven).[12] The fourth boat was ordered on 21 May 2007, to be called Audacious, and the names of the other hulls have been agreed as Agamemnon, Anson, and Ajax.[13] On 15 September 2011 it was announced that hull 5 would now be named Anson.[14] Upon the beginning of sea trials of Astute in November 2009, it was reported that long-lead items for hulls five and six have been ordered, including their nuclear reactor cores, and that the stated intention of the MoD was for a total of seven Astute-class submarines.[15] On 25 March 2010, BAE Systems were given the go-ahead by the government to begin construction on hulls 5 and 6, being given a £300 million contract for the "initial build" of hull five and "long lead procurement activities" for boat six.[16] In the same week the government re-affirmed their commitment to the construction of seven Astute-class submarines.

Work on the second and third submarines, Ambush and Artful, proceeded well with major milestones such as the closure of Ambush's reactor compartment, demonstrating significant schedule advance compared with Astute. BAE Systems and the MoD have made efforts to reduce costs and achieved significant cost-cutting and productivity gains.[17] A £580 million cost increase was agreed in 2007 due to maturing of the design requiring more materials, inflationary costs, and "some programme throughput assumptions at the Barrow site not being borne out."[9] First-of-class HMS Astute was launched by Camilla, Duchess of Cornwall on 8 June 2007.[18]

The order of seven Astute-class boats was confirmed in the Strategic Defence and Security Review of October 2010. In December that year it was confirmed by the MoD that "early work" was under way on boats five and six.[19]

On 13 October 2011, the fifth boat, Anson, was laid down at Devonshire Dock Hall and is now under construction like boats three and four. On 10 December 2012 the MOD awarded BAE a £1.2 billion contract for work on Audacious. The MOD also confirmed on the same date a further £1.5 billion funding for submarines Anson, Agamemnon and Ajax.[citation needed] The MOD Defence Equipment Plan 2012 refers to 'the completion of the remainder of the seven class of Astute attack submarines'.[20]

Programme delays

BAE Systems issued a profit warning on 11 December 2002 as a result of the cost overruns and delays it was experiencing with the Astute class and also the Nimrod MRA4 maritime reconnaissance/attack aircraft.[21] The delay was caused primarily by the problems of using 3D CAD; Armed Forces Minister Adam Ingram said in 2006 that "due to the complexity of the programme, the benefits that CAD was envisaged to provide were more difficult to realise than either MoD or the contractor had assumed."[22] Other issues were the insufficient capabilities within GEC-Marconi which became evident after contract-award and poor programme management.[11][23][24] BAE and the Ministry of Defence reached an agreement in February 2003 whereby they would invest £250 million and £430 million respectively to address the programme's difficulties.[9]

A major element of this was the enlisting of advice and expertise from General Dynamics Electric Boat.[25] The MoD also signed a design and production drawing work contract through the U.S. Navy which ran from 2004 to 2007.[26]

As of March 2008 the programme was 48 per cent (or £1.2 billion) over-budget and 47 months late.[9] Further delays due to a range of technical and programme issues brought the programme to a position of 57 months late and 53 per cent (or £1.35 billion) over-budget by November 2009, with a forecast cost of £3.9 billion for the first three Astute boats.[27] In June 2012 the order was placed for the manufacture of the nuclear reactor for the seventh Astute-class submarine Ajax alongside the refurbishment of Rolls-Royce manufacturing facility in Raynesway, Derby and the development and production of the first reactor for the next generation of SSBN to replace the Vanguard class.[28]

Some serious quality assurance problems have been identified in the first boats built. Due to the failure of a pipe cap, made of incorrect material although construction records indicated the correct metal had been used, Astute was forced to surface following a leak that was flooding a compartment. Other problems have been identified, including the wrong type of lead being used in a reactor instrument, and other quality issues leading to early corrosion of components.[29][30]


The boats of the Astute class are powered by a Rolls-Royce PWR2 (Core H) (a pressurised water) reactor and fitted with a pump-jet propulsor. The PWR2 reactor was developed for the Vanguard-class ballistic missile submarines. As a result the new submarines are about 30 per cent larger than previous British fleet submarines, which were powered by smaller-diameter reactors. Like all Royal Navy submarines, the bridge fin of the Astute-class boats is specially reinforced to allow surfacing through ice caps. These submarines can also be fitted with a dry deck shelter, which allows special forces (e.g. SBS) to deploy whilst the submarine is submerged.[31] More than 39,000 acoustic tiles mask the vessel's sonar signature, giving the Astute class a better stealth quality than any other submarine previously operated by the Royal Navy.[32] Speculation released by the media stated that by using advanced stealth technology Astute "makes less noise than a baby dolphin, making her as good as undetectable by enemy ships."[33]

Astute is the first Royal Navy submarine class to have a bunk for each member of the ship's company,[34] ending the practice of 'hot bunking', whereby two sailors on opposite watches shared the same bunk at different times. However, they have less mess-deck space than the Valiant-class submarine built 45 years earlier.[35][36]

The Royal Navy announced a speed of 29+ knots for the class, but it is reported this speed could not be reached in the trials of Astute due to a propulsion design problem. It is unclear if this problem can be overcome, and at the launch of the Ambush the Royal Navy only stated she was "capable of speeds in excess of 20 knots".[37][38]

Weapons and systems

The UK First Sea Lord, Admiral Stanhope (left), and US Chief of Naval Operations, Admiral Jonathan Greenert (centre), are briefed by the CO (right) on the capabilities of Astute during the joint exercise Fellowship 2012 between Astute and New Mexico

The Astute class has stowage for 38 weapons and would typically carry both Spearfish heavy torpedoes and Tomahawk Block IV cruise missiles, the latter costing £870,000 each.[39] The Tomahawk missiles are capable of hitting a target to within a few metres within a range of 1,240 miles[40] (2,000 km). The Astute class will also be able to fire the new "tactical Tomahawk" currently under development. The Astute Combat Management System is an evolved version of the Submarine Command System used on other classes of British submarine. The system receives data from the boat's sensors and displays real time imagery on all command consoles. The submarines also have Atlas Hydrographic DESO 25 high-precision echosounders, two CM010 non-hull-penetrating optronic masts—in place of conventional periscopes—which carry thermal imaging and low-light TV and colour CCD TV sensors.[41] The class also mounts a Raytheon Successor IFF system.

For detecting enemy ships and submarines the Astute class are equipped with the sophisticated Thales Underwater Systems Sonar 2076, an integrated passive/active search and attack sonar suite with bow, intercept, flank and towed arrays. BAE claims that the 2076 represents a "step change" over previous sonars and is the world's most advanced and effective sonar system.[42]

In 2012, during simulated battles with the United States Navy's latest Virginia-class submarine (the USS New Mexico), it was reported that the Americans were "taken aback" by Astute's capabilities. Royal Navy Commander Ian Breckenridge was quoted saying: “Our sonar is fantastic and I have never before experienced holding a submarine at the range we were holding USS New Mexico. The Americans were utterly taken aback, blown away with what they were seeing.”[43][44]

Boats of the class

Some aspects of the later Astute-class submarines will be different from boats 1-3, mostly related to the combat system—primarily the command, navigation and sonar systems. Audacious is the first Royal Navy submarine to use a shared computer environment for the different systems, common consoles and cabinets, and commercial "off-the-shelf" hardware and software, to reduce costs and improve maintainability. These changes have been back-fitted to boat 3, Artful; the eventual aim is to back-fit the "Common Combat System" to Astute and Ambush, and progressively to the rest of the Royal Navy submarine fleet.[45]

Name Hull Pennant number Status Ordered Laid down Launched Date of commission
Astute 1 S119 Commissioned March 1997 31 January 2001 8 June 2007[46] 27 August 2010[47]
Ambush 2 S120 Commissioned March 1997 22 October 2003 6 January 2011[6] 1 March 2013[48]
Artful 3 S121 Under construction March 1997 11 March 2005 17 May 2014 18 March 2016[49]
Audacious 4 S122 Under construction May 2007 24 March 2009 28 April 2017 03 April 2020[49]
Anson 5 S123 Under construction[50] March 2010 Unknown In service 2021[49]
Agamemnon 6 S124 Under construction[51] March 2010 18 July 2013 In service 2023[49]
Agincourt 7 S125 Under construction[52] March 2018 May 2018 In service 2026[49]

See also


  1. "Ministry of Defence: The Major Projects Report 2011" (PDF). National Audit Office. 16 November 2011. p. 41. 
  2. "HMS Astute". Royal Navy. Retrieved 30 January 2012. 
  3. ASTUTE CLASS, Royal Navy
  4. "UK's most powerful submarine joins the Navy". MoD. 27 Aug 2010. Retrieved 11 April 2011. 
  5. "Naval Technology — SSN Astute Class project details". Retrieved 8 January 2012. 
  6. 6.0 6.1 "BAE Systems Barrow submarine Ambush’s maiden voyage". NW Evening Mail. 7 January 2011. Retrieved 26 January 2011. 
  7. "HMS Ambush Officially Welcomed Into The Royal Navy". Royal Navy. Retrieved March 2, 2013. 
  8. "The Future of RN - Maritime contribution to Joint Operations (DNS presentation TO GREEK XX) by Commodore Tom Cunningham, Director of The Naval Staff Division.". Retrieved 8 January 2012. 
  9. 9.0 9.1 9.2 9.3 National Audit Office Ministry of Defence Major Projects Report 2008: Project Summary Sheets p.24
  10. Department of the Official Report (Hansard), House of Commons, Westminster. "House of Commons Hansard Written Answers for 3 September 2007". Retrieved 7 November 2011. 
  11. 11.0 11.1 "Mr Astute". Naval 31 August 2007. Retrieved 4 November 2010. 
  12. "New nuclear sub is lifeline for Barrow". BBC News Online. 28 August 2006. Retrieved 9 March 2007. 
  13. "National Archive - Royal Navy - Careers - Live Chat". National Archive. Retrieved 4 May 2012. 
  14. "Navy's newest Astute Class submarine named". Ministry of Defence. 15 September 2011. Retrieved 15 September 2011. 
  15. "Britain's £1.3bn new sub Astute sets sail" The Independent (17 November 2009)
  16. "£300M Order Boost For Shipyard". North West Evening Mail. Retrieved 7 November 2011. 
  17. Boxell, James (24 November 2006). "Royal Navy's weapons projects affected by delays and cost troubles". Financial Times. The Financial Times Limited. p. 2. 
  18. "New UK nuclear submarine launched". BBC News. 8 June 2007. Archived from the original on 18 June 2007. Retrieved 15 June 2007. 
  19. "Defence News &#124 Equipment and Logistics | Second Astute Class submarine officially named". Ministry of Defence. 20 February 2007. Retrieved 7 November 2011. 
  20. "BAE Systems and DCNS to cooperate on Astute-class submarine programme". September 10, 2013. 
  21. Odell, Mark (12 December 2002). "BAE warning sends share price to seven-year low: News of 'additional issues' on two big defence contracts takes market by surprise". Financial Times. 
  22. Department of the Official Report (Hansard), House of Commons, Westminster. "House of Commons Hansard Written Answers for 9 Mar 2006". Retrieved 7 November 2011. 
  23. Ilett, Dan (15 March 2006). "MPs probe £900m overspend on late submarines".,3800010403,39157227,00.htm?r=1. Retrieved 7 November 2011. 
  24. National Audit Office Ministry of Defence Major Projects Report 2008: Project Summary Sheets "Exceptional difficulties arose with the introduction of a computer aided design system, the availability of trained staff and project management"
  25. "US team to work on submarine order". BBC News. 8 April 2003. Retrieved 3 January 2007. 
  26. "U.S. Navy contracts". U.S. Department of Defense. 3 September 2004. Archived from the original on 15 February 2008. Retrieved 13 February 2008. 
  27. Defence Select Committee (23 February 2010). "Defence Equipment 2010". House of Commons. p. Ev 97. HC 99. Retrieved 9 March 2010. 
  29. Nick Hopkins (15 November 2012). "Slow, leaky, rusty: Britain's 10bn submarine beset by design flaws". Retrieved 20 November 2012. 
  30. Nick Hopkins and Rob Edwards (16 November 2012). "Submarine corrosion caused by cost-cutting, says leaked MoD memo". Retrieved 20 November 2012. 
  31. "Dr Lee Willett, The ''Astute''-Class Submarine, Capabilities and Challenges, RUSI (2004)" (PDF). Retrieved 7 November 2011. 
  32. "Countdown to launch of first ''Astute'' submarine at Barrow shipyard". Retrieved 7 November 2011. 
  33. unknown (14 February 2006). "Britain launches massive submarine that can hear a ship from across the Atlantic". Retrieved 30 January 2012. 
  34. Astute Fascinating Facts
  35. "Defence Nuclear Programme Human Resource Study". Ministry of Defence. 1 July 2009. Defence Board (09)33. Retrieved 16 April 2011. "we must not repeat the retrograde step made with the Astute class SSN, where the sailors will have less mess-deck space than in HMS Valiant built 45 years ago." 
  36. "Defence Nuclear Programme Human Resources Study - An Audit by Defence Operational Capability". Ministry of Defence. 1 July 2010. Defence Board (10)XX. Retrieved 16 April 2011. "Recommendation ... on-board accommodation standards and quality of life issues are thoroughly addressed in order to avoid the mistakes made with the Astute class." 
  37. Nick Hopkins (15 November 2012). "Britain's nuclear hunter-killer submarines were doomed from the start". Retrieved 19 November 2012. 
  38. Andrew Hough (16 November 2012). "HMS Astute: nuclear submarine beset by design problems and construction failures". Retrieved 19 November 2012. 
  39. "House of Commons Hansard - Written Answers for Daily Hansard - Written Answers 17 May 2011". UK Parliament. 17 May 2011. Retrieved 6 November 2011. 
  40. "Set to launch, our nuclear Leviathan: The enormous scale of the biggest submarine ever built in Britain". London: 14 December 2010. Retrieved 9 April 2011. 
  41. BBC News Scotland, A vision of evolving technologies 30 August 2007, 13:06 GMT
  42. "Press Release". BAE Systems. 2002. 
  43. HMS Astute arrives home from US sea trials
  44. Awesome Astute “Surpassed Every Expectation” on Her Toughest Test Yet
  45. BAE Systems News, 10 December 2012
  46. "New UK nuclear submarine launched". BBC. 8 June 2007. Archived from the original on 18 June 2007. Retrieved 8 June 2007. 
  47. "Royal Navy's Most Powerful Submarine Gets Royal Approval". Ministry of Defence. 27 August 2010. Archived from the original on 10 September 2010. 
  48. "HMS Ambush Officially Welcomed Into The Royal Navy". Royal Navy. 2013-03-01. Retrieved 2013-03-07. 
  49. 49.0 49.1 49.2 49.3 49.4 "House of Commons Written Answers c45W". UK Parliament. 3 September 2012. Retrieved 13 July 2013. 
  50. Naval Ship Building Boat 5 news
  51. Sixth Astute Class submarine keel laid
  52. UK: BAE Systems Secures $ 1.92 Bln Submarine Deal

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