Astute-class submarine

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Astute class SSN.svg
Astute-class SSN profile
HMS Ambush long.jpg
HMS Ambush in 2012
Class overview
NameAstute class
BuildersBAE Systems Maritime – Submarines, Barrow-in-Furness
Operators Royal Navy
Preceded by Trafalgar class
CostOver £1.3 billion per boat (2015 est.)[1]
In commission2010–present
General characteristics
TypeNuclear-powered fleet submarine
  • Surfaced: 7,000 to 7,400 t (7,300 long tons; 8,200 short tons)[2][3]
  • Submerged: 7,400 to 7,800 t (7,700 long tons; 8,600 short tons)[2][3]
Length97 m (318 ft 3 in)[2][3]
Beam11.3 m (37 ft 1 in)[2][3]
Draught10 m (32 ft 10 in)[2][3]
PropulsionRolls-Royce PWR 2 reactor, MTU 600 kilowatt diesel generators
Speed30 kn (56 km/h; 35 mph), submerged[2][3]
Endurance90 days limited only by the amount of food carried and endurance of the crew[4]
Test depthOver 300 m (984 ft 3 in)
Complement98 (capacity for 109)[2]
Sensors and
processing systems

The Astute class is the latest class of nuclear-powered fleet submarines (SSNs) in service with the Royal Navy.[3] 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 Maritime – Submarines at Barrow-in-Furness.[6] Seven boats will be constructed: the first of class, Astute, was launched by Camilla, Duchess of Cornwall, in 2007,[7] commissioned in 2010, and declared fully operational in May 2014.[3] The Astute class is the replacement for the Trafalgar-class fleet submarines in Royal Navy service.[3]


Batch 2 Trafalgar class

The Astute-class programme began in the 1980s when the Ministry of Defence (MOD) launched a number of studies intended to determine the capabilities and requirements for the replacement of its Swiftsure and Trafalgar-class fleet submarines.[8] These studies, called project SSN20, were conducted during the Cold War, when the Royal Navy maintained a strong emphasis on anti-submarine warfare to counter increasingly more capable Soviet submarines. To match this growing threat, the studies concluded that project SSN20 should be a revolutionary design, with significantly enhanced nuclear propulsion and firepower, and a more sophisticated "integrated sonar suite" and combat systems.[8] Similarly, the United States Navy, which was facing the same threats, went on to design and build the Seawolf class. The estimated costs of project SSN20, although great, were not considered a "constraint".[8]

However by 1990, the Berlin wall collapsed and the Cold War came to an end. Project SSN20 was promptly cancelled and a new set of design studies were started, this time, with "cost control" as a key objective.[8] The Trafalgar class had been an evolved derivative of the preceding Swiftsure class, thus, in order to reduce cost and technical risk, it was concluded that this new class of fleet submarine should "build upon" the Trafalgar design. This became known as the Batch 2 Trafalgar class (B2TC), with approval for the studies phase given in June 1991.[8] While the philosophy behind B2TC was that of a modern and improved Trafalgar, early design concepts of B2TC were also heavily influenced by the then under construction Vanguard class, in particular, its nuclear steam raising plant (NSRP).[8]

Astute programme

Following two years of a studies phase on B2TC, the MOD decided to put the contract out to tender. A draft invitation to tender was announced in October 1993[8] and a final invitation to tender in July 1994.[8][9] The final invitation to tender involved a formal competition between GEC-Marconi/BMT Limited[8] and VSEL/Rolls-Royce,[8] with bids to be submitted in June 1995. GEC-Marconi and BMT had little experience with British submarine designs, whereas VSEL and Rolls-Royce were heavily involved in both British nuclear submarine design and construction. For example, VSEL was the owner of the Barrow shipyard, the only shipyard capable of building nuclear submarines in the United Kingdom.[8]

During the assessment phase of the bids put forward by both teams, the MOD favoured the GEC-Marconi/BMT design on both cost and capability grounds.[8] The bid put forward by VSEL/Rolls-Royce was less attractive and considered "an expensive and dull design."[8] In June 1995, VSEL was subject to a takeover by GEC-Marconi, and with it, the Barrow shipyard. In December of the same year, the MOD announced that GEC-Marconi was the preferred bidder. The bid put forward by GEC-Marconi included the innovative use of 3D CAD software and modular construction techniques. Although the MOD had awarded the contract to GEC-Marconi, partly due to its competitive cost, it was still considered too high for the MOD to sign off on.[8] The MOD and GEC-Marconi negotiated on a new price for the contract, amounting to £2.4 billion for the first three Astute submarines, plus in service support. The contract was signed on 14 March 1997, for what was now called the Astute programme, with a fixed maximum price, and any cost overruns being assumed by GEC-Marconi, the contractor.[8]

Although B2TC was intended to be a modest improvement over the Trafalgar class, it was not to be the case for Astute. With the signing of the contract in March 1997, GEC-Marconi started work on developing a complete and comprehensive design for the Astute programme.[8] Initial realisation was that the size of the Rolls-Royce PWR2 required a much larger boat (width and length) and significantly improved acoustic quieting. A new understanding was reached between the MOD and GEC-Marconi that this would be an entirely new class, and far more complex than originally envisioned.[8]

Construction, cost overruns and delays

The Astute class are built at the Devonshire Dock Hall, Barrow-in-Furness

In November 1999, British Aerospace bought out GEC-Marconi and created BAE Systems. At the time of the takeover, it had been approximately 20 years since the Vanguard class were designed, and the last of the boats had already been launched.[8] The work force at the Barrow shipyard had fallen from around 13,000, to 3,000. Key skills in design and engineering had been lost, predominantly through retirement or movement into other careers.[8] This created significant delays and challenges in getting the Astute programme from design phase and into construction phase. Further delays and cost increases were also caused by the 3D CAD software,[10] despite originally being touted as an innovative cost saving measure, by greatly reducing man-hours.[8] However, one of the reasons for this was a lack of experienced designers able to use the software and its expanded tools.[8]

Astute on the shiplift after her launch ceremony

Despite numerous difficulties, including incomplete design drawings, the first boat, Astute, was laid down on 31 January 2001. As planned, modular construction methods were used, with the boat being built in several ring-like modules, each up to several metres in length.[11] These were welded together using specially designed high-strength steel,[12] and then fitted out. From boat 2 onward however, vertical outfitting has been used, whereby the ring-like sections are "stood up on their ends."[13] This has better enabled the fitting of large and heavy equipment, and has also proved to be more efficient, with reportedly "thousands of man-hours saved".[13]

By 2002 both BAE and the MOD recognised they had underestimated the technical challenges and costs of the programme.[8] In August 2002 the programme was estimated to be over three years late and hundreds of millions of pounds over budget.[8] BAE Systems issued a profit warning on 11 December 2002 as a result of the cost overruns and delays.[14] BAE Systems and the MOD subsequently renegotiated the contract, with an understanding that the MOD had to share some of the financial risks.[8] In December 2003 the contract modifications were signed, with the MOD agreeing to add another £430 million to the programme and BAE Systems assuming £250 million of the cost overruns.[9] The MOD also enlisted the advice and expertise of General Dynamics Electric Boat through a U.S. Navy contract.[15][16] Eventually, a General Dynamics Electric Boat employee became the Astute Project Director at Barrow.[8]

Audacious under construction

Input from General Dynamics helped resolve many of the software issues associated with 3D CAD;[8] General Dynamics were also responsible for the introduction of vertical outfitting and other construction techniques. Consequently, much rework was needed on Astute now that detailed designs were complete.[8] On 8 June 2007 Astute was launched and boats 2 and 3 (Ambush and Artful) were at various stages of construction. A month previously, procurement for boat 4 (Audacious) had been agreed.[8] Boats 5 and 6 (Anson and Agamemnon) were approved in March 2010.[8] In June 2012 the order was placed for the manufacture of the nuclear reactor for boat 7 (Agincourt), production of the first nuclear reactor for the Dreadnought-class submarine was also ordered.[17] A 1.4 billion pounds order to construct Agamemnon was issued by the MOD to BAE Systems on 19 April 2017.[18][19]

In November 2009, a House of Commons Defence Select Committee found that delays due to technical and programme issues brought the Astute class to a position of being 57 months late and 53 per cent (or £1.35 billion) over-budget, with a forecast cost of £3.9 billion for the first three boats.[20]

Programme cost summary

National Audit Office: Major Projects Report 2015[1]
Expected cost to completion at approval Current forecast cost to completion Change
Boats 1–3 £2.233 billion £3.536 billion Template:Increasenegative
Boat 4 £1.279 billion £1.492 billion Template:Increasenegative
Boat 5 £1.464 billion £1.420 billion Positive decrease
Boat 6 £1.579 billion £1.533 billion Positive decrease
Boat 7 £1.642 billion £1.640 billion Positive decrease


Weapons and systems

Astute firing a Tomahawk Block IV cruise missile

The Astute class has stowage for 38 weapons and would typically carry a mix of Spearfish heavy torpedoes and Tomahawk Block IV cruise missiles, the latter costing £870,000 each.[21] The Tomahawk missiles are capable of hitting a target to within a few metres, to a range of 1,000 miles (1,600 kilometres).[22] The Astute Combat Management System is a new version of the Submarine Command System used on other classes of British submarine. The system receives data from the boat's sensors and displays the results on 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.[23] The class also mounts an Successor IFF system.

For detecting enemy ships and submarines, the Astute class are equipped with the sophisticated Sonar 2076, an integrated passive/active search and attack sonar suite with bow, intercept, flank and towed arrays. BAE claims that the 2076 is the world's best sonar system.[24] All of the Astute-class submarines will be fitted with the advanced Common Combat System.[25]

Propulsion and general specifications

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 and has a 25-year lifespan without the need for refuelling.[4] 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.[26] More than 39,000 acoustic tiles mask the vessel's sonar signature, giving the Astute class improved acoustic qualities over any other submarine previously operated by the Royal Navy.[27]

A 2009 safety assessment by the Defence Nuclear Safety Regulator concluded that PWR2 reactor safety was significantly short of good practice in comparable navies in two important areas: loss-of-coolant accident and control of submarine depth following emergency reactor shutdown.[28][29][30] The regulator concluded that PWR2 was "potentially vulnerable to a structural failure of the primary circuit", which is a failure mode with significant safety hazards to crew and the public.[31] Operational procedures have been amended to minimise these risks.[32]

Astute is the second Royal Navy submarine class, after the Vanguard class, to have a bunk for each member of the ship's company,[33] 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.[34][35]

Top speed issue

The Astute class are designed to achieve a top speed of 29–30 knots (54–56 km/h), but it was reported in 2012 that this speed could not be reached in trials due to a mismatch between the reactor and the turbine.[36][37] However, in January 2015, the National Audit Office confirmed that demonstration of the top speed requirement (or Key Performance Measure (KPM)) for the Astute class was successful.[38][39]


  • On 22 October 2010, the Ministry of Defence confirmed that Astute had "run into difficulties" off the Isle of Skye while on trials, after eyewitnesses reported the submarine had run aground a few miles from the Skye Bridge. There were no reports of injuries.[40]
  • On 20 July 2016, Ambush sustained damage to the top of her conning tower during a collision with a merchant ship while surfacing on an exercise in Gibraltarian waters.[41] It was reported that no crew members were injured during the collision and that the submarine's nuclear reactor section remained completely undamaged.[42][43][44]

Boats of the class

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

In 2012, during the joint exercise Fellowship, Astute performed simulated battles with the latest United States Navy Virginia-class submarine, USS New Mexico. A government press release reported that the Americans were "taken aback" by Astute's capabilities. Royal Navy Commander Iain Breckenridge was quoted, "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".[45][46]

The names Astute, Ambush and Artful were last given to Amphion-class submarines that entered service towards the end of World War II.

Name Pennant No. Builder Laid down Launched Commissioned Status
Astute S119 BAE Systems Maritime – Submarines, Barrow-in-Furness 31 January 2001 8 June 2007[47] 27 August 2010[48] In active service
Ambush S120 22 October 2003 6 January 2011[49] 1 March 2013[50] In active service
Artful S121 11 March 2005 17 May 2014[51] 18 March 2016 [52] In active service
Audacious S122 24 March 2009 28 April 2017[53] Expected 2018[54] Testing and Fitting Out
Anson S123 13 October 2011 Expected 2020[54] Under construction[55]
Agamemnon S124 18 July 2013 Expected 2022[54] Under construction[56]
Agincourt[57] S125 Expected 2024[54] Under construction

In fiction

Season two of the American television series The Last Ship features a fictional Astute-class submarine named HMS Achilles as the primary antagonist.

See also


  1. 1.0 1.1 National Audit Office: Major Projects Report 2015 (PDF). United Kingdom: National Audit Office. 20 October 2015. p. 42. Retrieved 27 July 2016.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Bush, Steve (2014). British Warships and Auxiliaries. Maritime Books. pp. 10–11. ISBN 1904459552.
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 "Astute-class attack submarines". Royal Navy. Retrieved 27 July 2016.
  4. 4.0 4.1 4.2 "BAE Systems - Astute class submarines". BAE Systems. Retrieved 25 July 2016.
  5. "UK's most powerful submarine joins the Navy". Ministry of Defence. 27 August 2010. Retrieved 11 April 2011.
  6. "Naval Technology — SSN Astute Class project details". Retrieved 8 January 2012.
  7. "New UK nuclear submarine launched". BBC News. 8 June 2007. Archived from the original on 18 June 2007. Retrieved 15 June 2007. Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  8. 8.00 8.01 8.02 8.03 8.04 8.05 8.06 8.07 8.08 8.09 8.10 8.11 8.12 8.13 8.14 8.15 8.16 8.17 8.18 8.19 8.20 8.21 8.22 8.23 8.24 8.25 8.26 8.27 8.28 Lessons from the United Kingdom’s Astute Submarine Program (PDF) (Learning From Experience: Volume III ed.). United States: RAND National Defence Research Institute. Retrieved 27 July 2016.
  9. 9.0 9.1 "Ministry of Defence: Major Projects Report 2008". National Audit Office, 18 December 2008. Retrieved 27 July 2016.
  10. Department of the Official Report (Hansard), House of Commons, Westminster. "House of Commons Hansard Written Answers for 9 Mar 2006". Retrieved 7 November 2011.CS1 maint: multiple names: authors list (link)
  11. "An astute strategy". The Engineer. 3 May 2001. Retrieved 27 July 2016.
  12. "Welding Astute-Class Submarines". American Welding Society. Retrieved 27 July 2016.
  13. 13.0 13.1 "Mr Astute". Naval Technology. 31 August 2007. Retrieved 27 July 2016.
  14. 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.
  15. "US team to work on submarine order". BBC News. 8 April 2003. Retrieved 3 January 2007.
  16. "U.S. Navy contracts". U.S. Department of Defense. 3 September 2004. Archived from the original on 15 February 2008. Retrieved 13 February 2008. Cite journal requires |journal= (help)
  17. "£1bn contract for UK nuclear submarines to be announced". BBC News Online. 17 June 2012.
  18. Alan Tovey (19 April 2017). "MoD's £1.4bn deal with BAE for nuclear submarine gives company extra firepower". Telegraph Business.
  19. "BAE Systems gets £1.4B to build Royal Navy's sixth Astute-class submarine". 19 April 2017.
  20. Defence Select Committee (23 February 2010). "Defence Equipment 2010" (PDF). House of Commons: Ev 97. HC 99. Retrieved 9 March 2010. Cite journal requires |journal= (help)
  21. "House of Commons Hansard - Written Answers for Daily Hansard - Written Answers 17 May 2011". UK Parliament. 17 May 2011. Retrieved 6 November 2011.
  22. "United States Navy Fact File: Tomahawk Land Attack Missile". US Navy. Retrieved 27 July 2016.
  23. BBC News Scotland, A vision of evolving technologies 30 August 2007, 13:06 GMT
  24. Press Release, BAE Systems, 2002, archived from the original on 9 September 2010 Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  25. "HMS Artful test fires first torpedo using new UK-made advanced Combat System - Royal Navy". Retrieved 25 July 2016.
  26. "Dr Lee Willett, The Astute-Class Submarine, Capabilities and Challenges, RUSI (2004)" (PDF). Archived from the original (PDF) on 28 September 2011. Retrieved 7 November 2011. Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  27. "Countdown to launch of first Astute submarine at Barrow shipyard". Retrieved 7 November 2011.
  28. Rob Edwards (10 March 2011). "Flaws in nuclear submarine reactors could be fatal, secret report warns". The Guardian. Retrieved 28 March 2011.
  29. Joseph Watts (11 March 2011). "Expert warned MoD on safety of Rolls-Royce nuclear sub reactors". Derby Telegraph. Archived from the original on 18 September 2012. Retrieved 28 March 2011. Unknown parameter |dead-url= ignored (|url-status= suggested) (help)
  30. "Annex B: Successor SSBN - Safety Regulator's advice on the selection of the propulsion plant in support of the future deterrent (4 November 2009)", Successor Submaring Project - Update (PDF), Ministry of Defence, 24 November 2009, p. 21, EC-14-02-02-01-14 / Annex B: DNSR/22/11/2, retrieved 28 March 2011
  31. "PWR3 Reactor chosen for Trident". 18 May 2011. Archived from the original on 22 July 2011.
  32. "CSA: Safety paramount for RN nuclear submarine reactors". Defence News. Ministry of Defence. 9 June 2011. Retrieved 17 June 2011.
  33. Astute Fascinating Facts
  34. "Defence Nuclear Programme Human Resource Study" (PDF). 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. Cite journal requires |journal= (help)
  35. "Defence Nuclear Programme Human Resources Study - An Audit by Defence Operational Capability" (PDF). 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. Cite journal requires |journal= (help)
  36. Nick Hopkins (15 November 2012). "Slow, leaky, rusty: Britain's 10bn submarine beset by design flaws". The Guardian. London. Retrieved 20 November 2012.
  37. Andrew Hough (16 November 2012). "HMS Astute: nuclear submarine beset by design problems and construction failures". Daily Telegraph. London. Retrieved 19 November 2012.
  38. "The Equipment Plan and major projects report 2014". UK Armed Forces Commentary. Retrieved 16 January 2015.
  39. Major Projects Report 2014 and the Equipment Plan 2014 to 2024: Appendices and project summary sheets (PDF). National Audit Office. 13 January 2015. p. 45. Retrieved 8 August 2016.
  40. "Nuclear submarine HMS Astute runs aground off Skye". BBC News. 22 October 2010. Retrieved 22 October 2010.
  41. Staufenberg, Jess. "Royal Navy nuclear submarine collides with merchant ship off coast of Gibraltar". Independent Newspaper. Retrieved 20 July 2016.
  42. "UK nuclear submarine collides with merchant vessel off Gibraltar". BBC News. Retrieved 21 July 2016.
  43. "Royal Navy Statement – 20 July 2016". UK Ministry of Defence. 20 July 2016. Retrieved 20 July 2016.
  44. "£1.1bn submarine limps into port after collision". The Times. 21 July 2016.
  45. "HMS Astute arrives home from US sea trials - Announcements - GOV.UK". Retrieved 25 July 2016.
  46. "Awesome Astute "surpassed every expectation" on her toughest test yet". Navy News. 1 March 2012. Retrieved 25 July 2016.
  47. "New UK nuclear submarine launched". BBC. 8 June 2007. Archived from the original on 18 June 2007. Retrieved 8 June 2007. Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  48. "Royal Navy's Most Powerful Submarine Gets Royal Approval". Ministry of Defence. 27 August 2010. Archived from the original on 10 September 2010.
  49. "HMS Ambush". Royal Navy. Retrieved 27 July 2016.
  50. "HMS Ambush Officially Welcomed Into The Royal Navy". Royal Navy. 1 March 2013. Retrieved 7 March 2013.
  51. "Home - BAE Systems - International". Retrieved 25 July 2016.
  52. "HMS Artful becomes a commissioned warship". Royal Navy. 18 March 2016. Retrieved 18 March 2016.
  53. "Fourth Astute Boat Leaves DDH". North West Evening Mail. 27 April 2017. Retrieved 27 April 2017.
  54. 54.0 54.1 54.2 54.3 "House of Commons Written Answers c45W". UK Parliament. 3 September 2012. Retrieved 13 July 2013.
  55. Naval Ship Building Boat 5 news
  56. "Sixth Astute Class submarine keel laid - News stories - GOV.UK". Retrieved 25 July 2016.
  57. "Royal Navy nuclear submarines to get £2.5bn boost". BBC News. Retrieved 14 May 2018.

External links

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