HMS Ajax (S125)

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For other ships of the same name, see HMS Ajax.
Career (UK) Royal Navy Ensign
Name: HMS Ajax
Namesake: Ajax, Greek hero
Builder: BAE Systems Submarine Solutions
Identification: Pennant number: S125
Status: Confirmed, not yet ordered
Badge: HMS Ajax crest.jpg
General characteristics
Class and type: Astute-class submarine
Displacement: 7,400 tonnes, submerged[1]
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[1]
Range: Only limited by food and maintenance requirements.
Complement: 98 (capacity for 109)
Sensors and
processing systems:
Armament: 6 × 21-inch (533 mm) torpedo tubes with stowage for up to 38 weapons:[2]

HMS Ajax is a proposed Astute-class nuclear-powered fleet submarine of the Royal Navy and will be the seventh in her class. She will be the ninth vessel of the Royal Navy to bear the name, after the Greek hero Ajax.

The confirmation for the seventh and final Astute-class boat was given in the Strategic Defence and Security Review of October 2010, although an order has yet to be placed.[3] On 11 December 2012 the British government announced that long-lead items had been ordered for boats 6 & 7.[4]


Propulsion system[edit]

A confusing press release suggested that Ajax would have the same PWR3 nuclear reactor as the Successor class SSBNs[5] but in October 2012 it was confirmed that she would have a PWR2 like the rest of the Astute class.[6] Ajax‍ '​s nuclear reactor will not need to be refuelled during the boat's 25 year service. Since the submarine can replenish her air supply and purify water underway and while submerged, she will be able to circumnavigate the planet without resurfacing. The submarine's main limitation will be from the three months supply of food carried for the 98 officers and ratings.


Ajax will have provision for up-to 38 weapons in six 21-inch (533 mm) torpedo tubes:[7]

  • Tomahawk Block IV land-attack missiles - range of 1,240 miles (2,000 kilometres)
  • Spearfish heavyweight torpedoes


  1. ^ a b "Astute Class". Royal Navy. Retrieved 9 June 2014. 
  2. ^ "UK's most powerful submarine joins the Navy". MoD. 27 Aug 2010. Retrieved 11 April 2011. 
  3. ^ MoD David Cameron to delay Trident replacement
  4. ^
  5. ^ "Royal Navy submarine contract awarded". UK Ministry of Defence. 18 June 2012. Retrieved 2013-10-12. 
  6. ^ "House of Commons - Written Answers Column 311W". Hansard. UK Parliament. 17 October 2012. Retrieved 2013-10-12. 
  7. ^ Alien submarine breaks technical barriers BBC News. (7 May 2007).

External links[edit]