Bay Class Auxiliary Ship Alternative Landing Ship Logistic (ALSL), United Kingdom

Four Bay Class Landing Ship Dock (Auxiliary) ships, LSD(A), are scheduled to enter service with the UK Royal Fleet Auxiliary by the end of 2007. Two ships have been built by Swan Hunter (Tyneside) at the Wallsend shipyard and two by BAE Systems at the Govan shipyard.

RFA Largs Bay (L3006) was launched in July 2003 at Swan Hunter Wallsend and was delivered in April 2006. It entered service in December 2006. RFA Mounts Bay (L3008) was launched in April 2004 at BAE Govan and was the first vessel of the class to enter service with the Royal Fleet Auxiliary in December 2005. RFA Cardigan Bay (L3009) was launched in April 2005 at Govan and commissioned in March 2007. RFA Lyme Bay (L3007) was launched in September 2005 at Wallsend and delivered in July 2007. It was commissioned in November 2007.

The vessels were not conventionally launched but were floated out by the flooding of the dry dock, rather than from a slipway.

In July 2006, the UK Ministry of Defence announced that RFA Lyme Bay would be transferred to BAE Systems' Govan for final integration and commissioning and that BAE Systems will take over design authority and provision of lead yard services for the whole programme.

The ALSL (Alternative Landing Ships Logistic) ships will replace Sir Geraint, Sir Tristram and Sir Percival of the 30-year-old Sir Bedivere class Landing Ships Logistic (LSL) and Sir Galahad, commissioned in 1987. These vessels were decommissioned in 2006.

The design of the ALSL ships is based on the Royal Schelde's Enforcer design and provides more than twice the lift capacity of the Sir Bedivere class.

Sir Joseph Isherwood Ltd, based at Newcastle upon Tyne, has been contracted to supply the computerised integrated logistic support and ship maintenance system.

MISSION

An Amphibious Task Group (ATG) includes Landing Platform Docks (LPD) and a Landing Platform Helicopter (LPH), which support the first wave of an amphibious assault, and the alternative landing ship logistic vessels which support the second wave of the assault. The availability of the ALSLs provides the amphibious task group with a new capability to lift the 3 Commando Brigade Royal Marines.

The first wave of troops are landed by the LPDs, HMS Albion and Bulwark and by the LPH, HMS Ocean, to establish a beachhead and landing zone.

The ALSL ships, positioned about 20km offshore, remain over-the-horizon during the first wave assault, launching helicopters and landing craft to offload the second wave of troops and equipment.

When the beach area and landing zone have been confirmed as secure the ALSL Bay Class vessels approach the landing zone to deploy Mexeflotes, motorised platoons for offloading the heavy vehicles.

ALSL BAY CLASS VEHICLE DECK

The large vehicle deck is directly accessible by the stern ramp and the side ramp. The vehicle deck can accommodate 24 Challenger 2 main battle tanks or more than 150 light jeeps. The vehicle capacity is 1,200 linear metres, three times larger than existing Landing Ship Logistics (LSL) vessels.

ALSL BAY CLASS UPPER DECK

Cargo handling systems include two 30t upper deck cranes for freight and cargo handling. The cranes are used for the transfer of equipment to landing craft or to the mexefloats deployed alongside.

FLOODABLE DECK

A floodable dock capable of operating one LCU Mk 10 utility landing craft is installed in the stern. A Mexeflote is secured to each side of the ship. The ship can also carry and operate two LCVP Mk 5 vehicle / personnel landing craft.

EMBARKED MILITARY FORCE

The Bay class will support an Embarked Military Force (EMF) of 350 fully equipped troops and up to 700 fully equipped troops in overload conditions in times of crisis or in war.

The wide clearways or throughways, referred to as the assault routes, run from the troop assembly points to the dock and the flight deck, allowing the fully equipped troops to move quickly and efficiently into position for disembarking.

WEAPONS

The ship design has included weight and space allocation for 30mm gun emplacements, a Phalanx close-in weapon system and decoy launchers for chaff and infrared flare rounds.

HELICOPTERS

The superstructure is located far forward to provide the large available space to the aft of the ship for the helicopter deck.

The helicopter deck has the capacity for two landing spots and allows simultaneous operation of two medium-size helicopters such as EH101 Merlin, although the ships are initially being fitted for a single serviced helicopter landing spot.

The helicopter deck structure is reinforced for two static load points and will also support operations by a Chinook helicopter, an MV-22 Osprey tiltrotor aircraft and Support and Amphibious Battlefield Rotorcraft. A helicopter hangar is not installed but an option for a retrofit helicopter shelter has been proposed.

BAY CLASS AUXILIARY SHIP PROPULSION

The ship's diesel electric propulsion system has two Wartsila 8L26 engines (2,240kW each), two Wartsila 12V26 engines (3,360kW each) and a standby diesel generator. Azimuthal thrusters and a dynamic positioning system are fitted for holding the position and heading steady during operations involving embarking or disembarking landing craft.

Imtech Marine and Industry is contracted to design and supply an automated and integrated ship management system with an integrated bridge, automated platform control system and a power control and management system.