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L-12 Ocean Class

The emphasis that future operations will place upon the ability to insert and extract troops into a country from the sea - either as deterrent forces or as part of a peacekeeping or humanitarian mission - demands that specialist shipping must be up to the job. HMS Ocean, launched in October 1995, is a step in this direction. She is the United Kingdom's first purpose built Landing Platform, Helicopter, designed to take Royal Marines and Army units anywhere in the world and land them by large helicopters and by landing craft. A very versatile ship, she cannot however land heavy tanks and for that role the Royal Navy looked to acquire replacements for Fearless and Intrepid (which are some thirty years old) in the shape of two new Albion-class Landing Platform Dock ships.

The name Ocean for British warships came into use following the capture of the French ship Ocean at the Battle of Lagos Bay in 1759. HMS Ocean was a British first-class battleship of 12950 tons displacement launched in 1898.

Commissioned in 1996, the HMS Ocean has repeatedly proven its worth. Almost immediately, it was diverted to Honduras to provide humanitarian support after a devastating hurricane. It replayed this role in Turkey after the highly destructive earthquake in 1999. A major highlight in its military career was when it was deployed offshore from Sierra Leone in 2000, where it assisted in the daring rescue of British soldiers kidnapped by militiamen. Its current mission is in the North Arabian Gulf supporting the war against terror in the region.

Depending on requirements, a word of warning may be required when considering commercial options. The Royal Navy's own experience with its Landing Platform Helicopter (LPH) HMS Ocean has been a difficult one: a ship designed and built more to commercial than naval ship-building standards has proved to be more difficult - and more costly - to maintain than anticipated.

The Prime Minister confirmed on 19 October 2010 [Official Report, columns 810-11], that the refit for HMS Ocean will go ahead. In preparation for this work, the Ministry of Defence (MOD) has placed contracts for some small preliminary studies to be conducted. As part of the upkeep program for all complex Royal Navy vessels, HMS Ocean's refit is subject to ongoing discussions involving members of the Surface Ship Support Alliance (the Ministry of Defence, Babcock Marine and BAE Systems Surface Ships). As no final decisions had been taken by February 2011 within the alliance, the MOD had not made any other contractual obligations for HMS Ocean's upkeep period, though it was committed to working closely with our industry partners to distribute upkeep work on a 'best for enterprise basis'.

L-12 Ocean - Design

HMS Ocean was built based on the design of the Invincible class aircraft carrier with a modified superstructure. The ship's unique features include mixed commercial and military specifications; commercial standards have been applied where ever possible, with military standards being used used in those areas where military performance is critical. For example, the structure was designed to requirements imposed by Lloyd's Register. Where the design did not conform to conventional classification hand calculations were performed. Unique design concepts were used to satisfy the military shock requirements.

Its hull is based on a variation of the HMS Invincible aircraft carrier design. In fact, it is heavier than the Invincible, being the largest vessel built for the Royal Navy in 40 years. It is divided into 17 major watertight compartments along its length. To meet the requirements for damage control the ship was divided into over 1000 water-tight compartments, where just over 90 percent being used. The remaining void spaces offer considerable potential for storage or to serve as equipment spaces.

Propulsion is provided by two Crossley Pielstick 16 PC2.6 V 200 medium speed diesel engines, rated at 23,904 hp, with two independent shafts and a five-bladed fixed pitch propeller. A 450 kW KaMeWa bow thruster is fitted. The maximum speed is 18 knots and the range is 8,000 miles. The Royal Navy's biggest ship, HMS Ocean is powered by two Crossley Pielstick diesel engines, which can generate a top speed of 18 knots. However, during full power trials, a speed of 20.6 knots was achieved. At 15 knots, the ship can reach a distance over 8,000 nautical miles. Care was taken to ensure redundancy in power generation to ensure the ship can continue operations even when damaged.

HMS Ocean is equipped with the BAE Systems ADAWS 2000 combat data system, Link 11, 14 and 16 communications, a Matra Marconi SATCOM 1D satellite communications system, and a Merlin computer link. The ADAWS 2000 combat data system, installed on both HMS Ocean and on the Royal Navy's Landing Platform Dock LPD assault ship, is compatible with the ships of the Royal Navy' s front line fleet. The self protection combat systems include four Oerlikon/BAE twin 30mm guns together with three Raytheon/General Dynamics Phalanx Mk 15 close-in weapon systems.

HMS Ocean's primary role is to carry an Embarked Military Force (EMF) of up to 800 men equipped with artillery, vehicles and stores, supported by 12 medium support helicopters, 6 attack helicopters and 4 Landing Craft Vehicle Personnel (LCVP) Mk 5 Landing Craft on davits. Ocean has already proved her value in operations as diverse as humanitarian relief in Central America and demonstrating the ability to deploy troops rapidly to Sierra Leone.

The ship carries a crew of 255, an aircrew of 206 and 480 marines. An additional 320 marines could be accomodated in a short term emergency. HMS Ocean is built around the commando aviation concept which was pioneered by the Royal Navy in the early 1960s. It can carry an embarked military force (EMF) of 803 troops together with their equipment, artillery, stores and vehicles. Accommodation has been carefully thought through to suit the EMF. The bulk of the troops are accommodated forward with routes running straight to the hanger assembly areas. All passageways and stairways have been designed such that a fully equipped marine can pass through with ease. In the old carriers, it took the marines an hour to get to their flight deck, whereas in the HMS Ocean, the marines could assemble at their assault stations within 20 minutes.

The vehicle deck has been designed to offer maximum loading flexibility. It is supported by side and stern ramps to allow easy access for 40 Land Rovers, 34 trailers and six 105 mm light guns. Interestingly, the ship is not designed to deploy heavy main battle tanks. The Royal Navy replaced HMS Fearless and HMS Intrepid with the new Landing Platform Dock ship for the transportation of heavy tanks.

Troops trying to take a contested beachhead need critical aviation support. This is provided by a tailored airgroup, which can include 12 Merlin medium support helicopters and eight Apache attack helicopters. The ship has full facilities for twelve EH101 Merlin and six Lynx helicopters, and landing and refuelling facilities for Chinook helicopters. Twenty Sea Harriers could be carried but not supported. The flight deck is 170m long x 32.6m wide and there are two aircraft lifts.

With the British purchase of the Apache attack helicopters in 2003, they can provide anti-tank, combat support and reconnaissance capability for the troops ashore. Due to careful space management, HMS Ocean can launch two waves of six Merlins within 30 minutes, backed by the Apaches. If necessary, the ship can land and refuel the larger Chinook transport helicopters. It is also designed to take into account all projected British helicopters and can cross-deck the American CH-46 Sea Knight and MV-22 Osprey tilt-rotor helicopters. If necessary, a total of 20 Sea Harrier aircraft can replace the helicopter group but cannot be supported on the ship.

HMS Ocean also serves as a command and communications headquarters for the amphibious forces. Using the Amphibious Operations Room, the commander uses the Defence Command Support System which consists of a large screen display facility and workstations to control the aviation and marine assets.

Being a high-value target, the LPH operates in conjunction with a task force, which provides it with an all-round defence. For close-range defence, the ship relies on three Phalanx 20mm close-in weapon systems and four Oerlikon/BAE twin 30mm guns. With an 8-launcher Outfit DLJ NATO Sea Gnat, it can fire chaff and infrared decoys to lure multiple incoming anti-ship missiles away.

Warships are often required to operate in very different ways and conditions compared to commercial vessels and also need to be able to withstand action damage. The Naval Engineering Standards adopted for the construction of warships re?ect this, although some warships are increasingly specified to a mixture of commercial and Naval Standards. Thus, the Department need a thorough understanding ofboth commercial and naval standards and the relationship between the two. As part of studies to assess the effect of easing requirements, the Department considered the extent to which Naval Engineering Standardscould be relaxed or replaced with commercial standards without prejudicing either functional requirements or personnel safety in line with the reduction in operational capability. As a result, the number of Naval Engineering Standards deemed necessary was reduced. The invitation to tender also allowed tenderers to suggest easements to standards where these would result in significant cost savings but required them to state the operational implications and quantify the savings.

There was no doubt that the LPH is a warship. However, it was to be built to the standards which are most appropriate to its operational role. Some military features are indispensable such as crew safety, ship survival standards [eg watertight subdivision and stability, the need for separated back-up systems, shock precautions, and fire safety] and operational requirements [eg helicopter arrangements and radar capability]. In addition the LPH, like most warships, is required to be self-supporting for long periods at sea. In consequence there is a need for different, and in some cases, more demanding availability, reliability and maintainability characteristics than would be the case for most commercial vessels.

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Page last modified: 11-07-2011 02:59:40 ZULU