 Astute-class SSN profile | |
 HMS ‘’Ambush’’ in 2012 | |
| Class overview | |
|---|---|
| Name | Astute class |
| Builders | BAE Systems Submarines,Barrow-in-Furness |
| Operators |  Royal Navy |
| Preceded by | Trafalgar class |
| Succeeded by | SSN-AUKUS (First design contract awarded) |
| Cost | Over£1.65billion per boat (2015 est.) |
| Built | 2001–present |
| In commission | 2010–present |
| Planned | 7 |
| Building | 1 |
| Completed | 6 |
| Active | 5 |
| General characteristics | |
| Type | Nuclear-poweredattack submarine |
| Displacement | |
| Length | 97 m (318 ft 3 in)[1][2] |
| Beam | 11.3 m (37 ft 1 in)[1][2] |
| Draught | 10 m (32 ft 10 in)[1][2] |
| Propulsion |
|
| Speed | 30knots (56 km/h; 35 mph), submerged[1][2] |
| Range | Unlimited[3] |
| Endurance | Unlimited in terms of propulsion, air and water, but otherwise typically 90 days, based on the amount of food carried and endurance of the crew[3] |
| Test depth | Over 300 m (980 ft) |
| Complement | 98 (capacity for 109)[1] |
| Sensors and processing systems | |
| Armament |
|
TheAstute class is the latest class ofnuclear-poweredattack submarines in service with theRoyal Navy.[2] The boats are constructed byBAE Systems Submarines atBarrow-in-Furness.[6] Seven boats will be constructed: the first of class,Astute, was launched byCamilla, Duchess of Cornwall, in 2007,[7]commissioned in 2010, and declared fully operational in May 2014.[2] TheAstute class is the replacement for theTrafalgar-class fleet submarines in Royal Navy service.[2]
TheAstute-class programme began in February 1986 when theMinistry of Defence (MOD) launched a number of studies intended to determine the capabilities and requirements for the replacement of itsSwiftsure andTrafalgar-class fleet submarines.[8][9] These studies, called project SSN20, were conducted during theCold War, when the Royal Navy maintained a strong emphasis onanti-submarine warfare to counter increasingly capableSoviet 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.[9] Similarly, theUnited States Navy, which was facing the same threats, went on to design and build theSeawolf class. The estimated costs of project SSN20, although great, were not considered a "constraint".[9]
However, by 1990 theBerlin Wall had fallen 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.[9] TheTrafalgar class had been an evolved derivative of the precedingSwiftsure class, and in order to reduce cost and technical risk it was concluded that this new class of fleet submarine should "build upon" theTrafalgar design. This became known as the Batch 2Trafalgar class (B2TC), with approval for the studies phase given in June 1991.[9] While the philosophy behind B2TC was that of a modern and improvedTrafalgar, early design concepts of B2TC were also heavily influenced by the then under constructionVanguard class, in particular its nuclear steam raising plant (NSRP).[9]
Following two years of a studies phase on B2TC, the MOD issued a draftinvitation to tender in October 1993 and a final invitation to tender in July 1994.[9] The final invitation to tender involved a formal competition betweenGEC-Marconi/BMT Limited andVSEL/Rolls-Royce, with bids to be submitted in June 1995.[9] 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.
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.[9] The bid put forward by VSEL/Rolls-Royce was less attractive and considered "an expensive and dull design."[9] 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 of3D 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.[9] The MOD and GEC-Marconi negotiated on a new price for the contract, amounting to £2.4 billion for the first threeAstute submarines, plus in-service support. The contract was signed on 14 March 1997, for what was now called theAstute programme, with a fixed maximum price, and any cost overruns being assumed by GEC-Marconi, the contractor.[9]
Although B2TC was intended to be a modest improvement over theTrafalgar class, it was not to be the case forAstute. With the signing of the contract in March 1997, GEC-Marconi started work on developing a complete and comprehensive design for theAstute programme.[9] Initial realisation was that the size of theRolls-Royce PWR2 required a much larger boat (beam 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.[9]
In November 1999,British Aerospace purchased GEC-Marconi and createdBAE Systems. At the time of the takeover, it had been approximately 20 years since theVanguard class was designed, and the last of the boats had already been launched.[9] The workforce 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.[9] This created significant delays and challenges in getting theAstute 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.[9] However, one of the reasons for this was a lack of experienced designers able to use the software and its expanded tools.[9]
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] The class is the first nuclear submarine to be designed entirely using 3D computer software.[3]
By 2002 both BAE and the MOD recognised they had underestimated the technical challenges and costs of the programme.[9] In August 2002 the programme was estimated to be over three years late and hundreds of millions of pounds over budget.[9] 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.[9] 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.[15] The MOD also enlisted the advice and expertise ofGeneral Dynamics Electric Boat through aU.S. Navy contract.[16] Eventually, a General Dynamics Electric Boat employee became the Astute Project Director at Barrow.[9]
Input from General Dynamics helped resolve many of the software issues associated with 3D CAD;[9] General Dynamics was also responsible for the introduction of vertical outfitting and other construction techniques. Consequently, much rework was needed onAstute now that detailed designs were complete.[9] On 8 June 2007Astute was launched and boats 2 and 3 (Ambush andArtful) were at various stages of construction. A month previously, procurement for boat 4 (Audacious) had been agreed.[9] Boats 5 and 6 (Anson andAgamemnon) were approved in March 2010.[9] In June 2012 the order was placed for the manufacture of the nuclear reactor for boat 7 (Achilles), as well as production of the first nuclear reactor for theDreadnought-class submarine.[17] A £1.4 billion order to constructAgamemnon was issued by the MOD to BAE Systems on 19 April 2017[18]
In November 2009, a House of Commons Defence Select Committee found that delays due to technical and programme issues brought theAstute 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.[19] The handover of boat 4, HMSAudacious, was delayed from 2019 to 2021 due to "emergent technical issues".[20] In February 2020, James Heappey, parliamentary under secretary of state for defence, confirmed that the in-service date for the final SSN, HMSAchilles, had slipped to 2026.[21]
In 2023, as part of the joint planning within theAUKUS defence group, it was indicated that, from 2027, one Astute-class submarine would forward operate on rotation fromHMAS Stirling inWestern Australia.[22]
| Expected cost to completion at approval | Current forecast cost to completion | Change | |
|---|---|---|---|
| Boats 1–3 | £2.233 billion | £3.536 billion |  58% Increase |
| Boat 4 | £1.279 billion | £1.492 billion | 16% Increase |
| Boat 5 | £1.464 billion | £1.420 billion |  3% Decrease |
| Boat 6 | £1.579 billion | £1.533 billion | 3% Decrease |
| Boat 7 | £1.642 billion | £1.640 billion |  |
In September 2021, the Ministry of Defence announced a £170 million investment into design work for the successor to theAstute-class. This funding included two £85 million contracts, which were awarded to BAE Systems and Rolls-Royce.[24] In March 2023, it was announced that the submarine would be a joint project between the United Kingdom, Australia and the United States and would start to replace theAstute-class in the Royal Navy in the late 2030s.[22][25]
_During_Testing_Near_the_USA_MOD_45153387.jpg)
TheAstute class has stowage for 38 weapons and would typically carry a mix ofSpearfish heavy torpedoes andTomahawk Block IV cruise missiles,[5] the latter costing £870,000 each.[26] The Tomahawk missiles are capable of hitting a target to within a few metres, to a range of 1,000 miles (1,600 kilometres).[27] In May 2022, the MOD announced that it would be upgrading these missiles to Block V standard from 2024, which boasts an extended range and modernised in-flight communication and target selection.[28] The Astute Combat Management System is a new version of theSubmarine 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 haveAtlas Hydrographic DESO 25 high-precision echosounders, two CM010 non-hull-penetratingoptronic masts—in place of conventionalperiscopes—which carry thermal imaging and low-light TV and colourCCD TV sensors.[29] The class also mounts aSuccessor IFF system.
For detecting enemy ships and submarines, theAstute class is equipped with the sophisticatedSonar 2076, an integrated passive/active search and attacksonar suite with bow, intercept, flank and towed arrays. BAE claims that the 2076 is the world's best sonar system.[30] All of the Astute-class submarines will be fitted with the advanced Common Combat System.[31]
The boats of theAstute class are powered by a Rolls-RoycePWR2 (Core H) (apressurised water reactor) and fitted with apump-jet propulsor. The PWR2 reactor, which was developed for theVanguard-class ballistic missile submarines, has a 25-year lifespan without the need for refuelling.[32][3] 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 theAstute-class boats is specially reinforced to allow surfacing through ice caps. These submarines can also be fitted with adry deck shelter, which allows special forces (e.g.SBS) to deploy whilst the submarine is submerged.[33] More than 39,000acoustic tiles mask the vessel's sonar signature, part of the acoustic qualities that theAstute class has over any other submarine previously operated by the Royal Navy.[34]
A 2009 safety assessment by the Defence Nuclear Safety Regulator concluded that PWR2 reactor safety was significantly short of good practice in two important areas:loss-of-coolant accident and control of submarine depth following emergency reactor shutdown.[35] 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.[36] Operational procedures have been amended to minimise these risks.[37]
Astute is the second Royal Navy submarine class, after theVanguard class, to have a bunk for each member of the ship's company,[38] 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 theValiant-classsubmarines built 45 years earlier[39] and a Defence Board audit recognised mistakes had been made on accommodation standards and quality of life issues.[40] Since it is nuclear powered, the boat has theoretically unlimited endurance, though in practice it is limited to 90 days at sea based on food carried (including 18,000 sausages and 4,200Weetabix) and crew endurance.[3]
In 2012, during the joint exercise Fellowship,Astute performed simulated battles with the latest United States NavyVirginia-class submarine,USS New Mexico. 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 USSNew Mexico. The Americans were utterly taken aback, blown away with what they were seeing".[41]
TheAstute 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.[42] However, in January 2015, theNational Audit Office confirmed that demonstration of the top speed requirement (or Key Performance Measure (KPM)) for theAstute class was successful.[43]
The namesAstute,Ambush andArtful were last given toAmphion-class submarines that entered service towards the end ofWorld War II.Audacious,Anson andAgamemnon were all names used by battleships that served in the First or Second World Wars.
| Name | Pennant No. | Builder | Laid down | Launched | Commissioned | Status |
|---|---|---|---|---|---|---|
| Astute | S119 | BAE Systems 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] | 3 April 2020[note 1] | In active service | |
| Anson | S123 | 13 October 2011 | 20 April 2021[56] | 31 August 2022[57][58] | In active service | |
| Agamemnon | S124 | 18 July 2013 | 3 October 2024[59] | Projected late 2025[60][58][61] | pre-sea trial testing | |
| Achilles (ex Agincourt)[62] | S125 | 14 May 2018[63][64] | Projected late 2026[58][61] | Under construction |
The Operational handover for AUDACIOUS is now planned for January 2021.
Recommendation ... on-board accommodation standards and quality of life issues are thoroughly addressed in order to avoid the mistakes made with theAstute class.
HMS AUDACIOUS was commissioned into the Royal Navy on 3 April 2020
Current and planned classes of nuclear-powered attack submarines | |
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 Royal Australian Navy | |
 Brazilian Navy |
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 People's Liberation Army Navy |
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 French Navy | |
 Indian Navy |
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 Russian Navy | |
| Royal Navy | |
 United States Navy |
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