Bay - class landing ship The " Bay " class is a ship class of four dock landing ship s built for the British Royal Fleet Auxiliary ( RFA ) during the 2000s . They are based on the Dutch - Spanish Royal Schelde Enforcer design and intended as a replacement for the Round Table class logistics ships . Two ships each were ordered from Swan Hunter and BAE Systems Naval Ships . Construction work started in 2002 , but saw major delays and cost overrun s , particularly at Swan Hunter ' s shipyard . In mid - 2006 , Swan Hunter was stripped of work , and the incomplete second ship was towed to BAE ' s shipyard for completion . All four ships , , , , and had entered service by 2007 . Since entering service , the Bay class ships have been used for amphibious operations , training of the Iraqi Navy in the Persian Gulf , counter - drug deployments in the Caribbean , and relief operations following the 2010 Haiti earthquake . In 2010 , " Largs Bay " was removed from service as part of the Strategic Defence and Security Review . She was sold to the Royal Australian Navy ( RAN ) in 2011 , who operate her as . Background . The Bay class was designed as a replacement for the five Round Table class logistics ships operated by the RFA . Planning for the class began in the 1990s , after the original intent to modernise and extend the service life of three Round Tables ran into problems with extensive corrosion and problems implementing new safety standards . After the first Round Table returned to service two years late and after excessive cost , the Ministry of Defence began to investigate the acquisition of new ships . In April 2000 , the MoD released an Invitation to Tender for two ships under a budget of £150 million , with the option to acquire three more . Appledore Shipbuilders , BAE Systems Naval Ships and Swan Hunter submitted tenders , but only Swan Hunter ' s design met all the tender requirements , at a price of £148 million . A shortfall of work for BAE ' s Govan yard led to fears that it could not deliver the Type 45 destroyer s and Queen Elizabeth class aircraft carrier s planned for later in the decade , so the Treasury agreed to fund an additional two LSDs to be built at Govan . Design . The Bay class is certified as a Class 1 Passenger Ship , with design similarities to ro - pax ferries . The design is based on the Royal Schelde Enforcer , a joint project between the Dutch and Spanish resulting in the " Rotterdam " class and " Galicia " class amphibious warfare ships . The main difference is that the British ships have no helicopter hangar . The ships were originally designated " Auxiliary Landing Ship Logistics " or ALSL , but this was changed in 2002 to " Landing Ship Dock ( Auxiliary ) " or LSD ( A ) , better reflecting their operational role and bringing them into line with the NATO designation for the Royal Schelde vessels . The Bay class ships have a full load displacement of . They are long , with a beam of , and a draught of . Propulsion power is provided by two Wärtsilä 8L26 generators , providing , and two Wärtsilä 12V26 generators , providing . These are used to drive two steerable azimuthing thrusters , with a bow thruster supplementing . Maximum speed is , and the Bay class ships can achieve a range of at . The ships were designed to receive an armament of two Phalanx CIWS , two manual 30 mm DS30B cannon and various small arms , but the exact weapons fit varies within the class . In British service , the everyday ship ' s company consisted of 60 to 70 RFA personnel , with this number supplemented by members of the British Armed Forces when the ships are deployed operationally . For example , " Largs Bay " s deployment in response to the 2010 Haiti earthquake saw her sail with a core crew of 70 , 40 Royal Logistic Corps personnel for boat - and cargo - handling duties , plus 17 from the Royal Navy and Royal Marines for security and related tasks . Australia operates " Choules " with a permanent crew of 158 including a Ship ' s Army Department of 22 . As a sealift ship , each Bay class vessel is capable of carrying up to 24 Challenger 2 tanks or 150 light trucks in 1 , 150 linear metres of space , with stern - and side - ramp access to the vehicle deck . The cargo capacity is equivalent of 200 tons of ammunition , or 24 twenty - foot equivalent unit containers . During normal conditions , a Bay class ship can carry 356 soldiers , but this can be almost doubled to 700 in overload conditions . The flight deck is capable of handling helicopters up to the size of Chinooks , as well as Merlin helicopters and Osprey tiltrotor aircraft . There is no hangar for long - term embarkation of a helicopter , although a temporary shelter can be fitted to house a Merlin or smaller helicopter . The well dock can carry one LCU Mark 10 or two LCVPs , and two Mexeflote s can be suspended from the ship ' s flanks . Two 30 - ton cranes are fitted between the superstructure and the flight deck . Internal passages are wide enough to allow two fully kitted marines to pass each other . Construction . The contract for and was awarded to Swan Hunter on 18 December 2000 and the £122 million contract for and was awarded to BAE on 19 November 2001 . Construction on " Largs Bay " started at Swan Hunter on 28 January 2002 , and on " Mounts Bay " at BAE on 25 August 2002 . Swan Hunter struggled to manage the project and contain costs ; only 7 % of the design drawings were provided on time and more than 52 % were over a year late . Jaap Kroese of Swan Hunter has blamed the MoD for continually changing the specifications . The extent of the problems only came to light in September 2003 when Swan Hunter said they could not fulfil the contract at the agreed price . In November 2004 progress on " Largs Bay " was delayed by water entering two engines during engine trials , putting the planned first of class behind work on BAE ' s first ship . The following month the government agreed to pay Swan Hunter an extra £84 million under new contract terms , but in June 2005 Swan Hunter said that they still could not finish the job within budget . This led to their contract being cancelled and BAE taking over the project in July 2006 . In total Swan Hunter had been paid £342 million and BAE £254 million , making a total of £596 million for the four ships . " Mounts Bay " entered service in July 2006 , followed by " Largs Bay " in November of that year , 28 months later than originally planned . The incomplete " Lyme Bay " was towed to Govan for completion by BAE . " Lyme Bay " was dedicated on 26 November 2007 ; the last ship of the class to enter RFA service . The ship was the only warship built by Swan Hunter but not completed ; she marked the end of shipbuilding on the Tyne as soon afterwards Swan Hunter sold its equipment to India and reinvented itself as an engineering consultancy . Operational history . The first - of - class " Mounts Bay " took part in Operation Vela , a major amphibious exercise off West Africa in 2006 . In mid - April 2007 , " Cardigan Bay " sailed for " Operation Orion 07 " , a four - month deployment to the Mediterranean . From 2008 until the end of 2010 , " Cardigan Bay " was used to accommodate and train personnel of the Iraqi Navy under the tutelage of Royal Navy and United States Navy personnel . During this time , the ship operated almost exclusively in the Persian Gulf . In late November 2007 , " Largs Bay " was deployed to the Caribbean for counter - drug operations . During the deployment , the ship made visited ports across the Caribbean islands and the United States mainland , and intercepted a cocaine shipment . In late 2008 , it was reported that " Largs Bay " was to replace for duties in the Falkland Islands . " Northumberland " was to have left for the Islands in December 2008 , but was instead sent for pirate patrol off Somalia . On 3 February 2010 , " Largs Bay " headed off to Haiti with aid supplies for relief efforts after the earthquake . On 18 February 2010 , she arrived at Port - au - Prince and commenced unloading of the supplies . On 30 March 2010 , she returned home . In December 2010 , it was announced that a Bay class vessel , later identified as " Largs Bay " , would be decommissioned in April 2011 as part of the Strategic Defence and Security Review . On 17 March 2011 , the Australian Department of Defence announced that the RAN would be bidding for " Largs Bay " ; this was followed on 6 April by news that a £65 million ( A $ 100 million ) bid had been successful . She was commissioned into the RAN on 13 December 2011 as , after receiving modifications for service in tropical conditions . A transformer in the propulsion system failed when she was en route to a training area on 14 June 2012 , after earlier reports that the ship could not maintain top speed without transformers overheating . An insulation failure had short - circuited the failed transformer , while others aboard were showing signs of premature wear . With no spares available , the need to order from the manufacturer combined with the decision to replace all of the transformers aboard meant that " Choules " will be kept out of service until April 2013 . In June 2011 , " Cardigan Bay " headed to Yemen to aid with the potential evacuation of British citizens affected by the ongoing unrest in Yemen .