HMAS Choules (L100) - Design and Construction

Design and Construction

The Bay class was designed as a replacement for the Round Table-class logistics ships operated by the RFA. The new design was based on the Royal Schelde Enforcer design; a joint project between the Dutch and Spanish resulting in the Rotterdam-class and Galicia -class amphibious warfare ships. The main difference with the British ships is the lack of a 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. Four ships were ordered; two from Swan Hunter, and two from BAE Systems Naval Ships.

The Bay-class ships have a full load displacement of 16,160 tonnes (15,900 long tons) in RFA service; this increased slightly to 16,190 tonnes (15,930 long tons) after modifications for RAN service. Largs Bay/Choules is 579.4 feet (176.6 m) long, with a beam of 86.6 feet (26.4 m), and a draught of 19 feet (5.8 m). Propulsion power is provided by two Wärtsilä 8L26 generators, providing 6,000 horsepower (4.5 MW), and two Wärtsilä 12V26 generators, providing 9,000 horsepower (6.7 MW). These are used to drive two steerable propulsion pods, with a bow thruster supplementing. Maximum speed is 18 knots (33 km/h; 21 mph), and the Bay-class ships can achieve a range of 8,000 nautical miles (15,000 km; 9,200 mi) at 15 knots (28 km/h; 17 mph). For self defence, Largs Bay was fitted with two Mk.44 miniguns and six 7.62mm L7 GPMGs, plus fitted for but not with a Phalanx CIWS and a 30 mm DS30B cannon. The RAN's webpage for Choules does not specify any armament. 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 Largs Bay was deployed operationally. The RAN opted to maintain the ship at full operational crewing at all times, with a ship's company of 158.

As a sealift ship, Largs Bay is capable of carrying up to 1,150 linear metres of vehicles; equivalent to 24 Challenger 2 tanks, 32 M1A1 Abrams tanks, or 150 light trucks. 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. No helicopters are carried on board, but the twin-spot flight deck is capable of handling helicopters up to the size of Chinooks, as well as Merlin helicopters and Osprey tiltrotor aircraft, and a temporary hangar can be fitted as required. The well dock can carry one LCU Mark 10, one LCM-8, or two LCVPs (either the Royal Marines version or the Royal Australian Navy version), and two Mexeflotes can be suspended from the ship's flanks. Two 30-ton cranes are fitted between the superstructure and the flight deck.

Largs Bay and sister ship Lyme Bay were ordered from Swan Hunter on 18 December 2000. Largs Bay was laid down at Swan Hunter's shipyard at Wallsend, Tyne and Wear on 28 January 2002; the first ship of the class work started on. The ship was launched on 18 July 2003. The ship was completed and accepted by the Ministry of Defence in April 2006, over a year late. Largs Bay was dedicated on 28 November 2006, the second of the class to enter service with the RFA. The Bay class construction project saw major delays and cost overruns, particularly in the Swan Hunter half of the project. Shortly after Largs Bay was handed over, Swan Hunter was stripped from the project, with BAE taking full responsibility for the class and Lyme Bay towed to BAE's shipyard in Govan for completion in June 2006.