Tarawa-class amphibious assault ship

The Tarawa class is a ship class of amphibious assault ships/LHA operated by the United States Navy (USN). Five ships were built by Ingalls Shipbuilding between 1971 and 1980; another four ships were planned, but later canceled. As of 2011, only one vessel is active, and the class is due to be replaced by the America class amphibious assault ships from 2013 onwards.

Design
The vessels have a full load displacement of 39967 t. Each ship is 834 ft long, with a beam of 131.9 ft, and a draft of 25.9 ft.

Propulsion is provided by two Combustion Engineering boilers, connected to two Westinghouse turbines. These supply 70000 hp to the ship's two propeller shafts. A Tarawa class vessel can reach a maximum speed of 24 kn, and has a maximum range of 10000 nmi at 20 kn. In addition to the main propulsion system, the ships are fitted with a bow thruster.

As of 1998, the ships' armament consists of a Mark 49 RAM surface-to-air missile system, two Vulcan Phalanx close-in weapons systems, six Mark 242 25 mm automatic cannons, and eight 12.7 mm machine guns. Previously, the amphibious warships were fitted with a Mark 25 Sea Sparrow missile system (which was replaced by the Phalanx units), and two 5-inch (127 mm) Mk 45 lightweight guns in bow sponsons (the guns were removed across the class during 1997 and 1998). Countermeasures and decoys include four Mark 36 SRBOC launchers, a SLQ-25 Nixie towed torpedo decoy, a Sea Gnat unit, SLQ-49 chaff decoys.

The number of helicopters carried by each vessel was up to 19 Sikorsky CH-53 Sea Stallions, 26 Boeing Vertol CH-46 Sea Knight, or a mix of the two. The 820 by flight deck is fitted with two aircraft lifts, and up to 9 Sea Stallions or 12 Sea Knights can be operated simultaneously. With a small amount of modification, the ships could carry and operate up to six McDonnell Douglas AV-8B Harrier II jump-jets.

The Tarawa class ships are designed to embark a reinforced battalion of the United States Marine Corps and their equipment. Onboard accommodation is provided for up to 1,703 marines, while 33730 cuft is provided for the battalion's vehicles, and 116900 cuft is allocated for stores and other equipment. As well as deploying by helicopters, personnel and equipment can be embarked or offloaded via a 268 by well deck in each ship's stern. Up to four LCU 1610 landing craft can be transported in and operated from the well deck, along with other designs and combinations of landing craft (two LCU and two LCM-8, or 17 LCM-6, or 45 LVT).

The Tarawa design was later repeated for the Wasp class amphibious assault ships, with some changes. The main changes to the latter eight-ship class include the lower placement of the ship's bridge aboard the Wasps, the relocation of the command and control facilities to inside the hull, modifications to allow the operation of Harrier jump-jets and Landing Craft Air Cushion hovercraft, and removal of the 5-inch guns and their sponsons to increase the overall size of the flight deck.

Construction
All five warships were built by Ingalls Shipbuilding, at this company's shipyard in Pascagoula, Mississippi. The Tarawa was approved for construction during Fiscal Year 1969, with two more ships of this class ordered by Congress in the 1970 and 1971 fiscal years. Nine ships of this class were originally contemplated for the Tarawa class, but just five were ordered and built, and the other four ships were never ordered by the Navy.

Work on the first warship of this class, the USS Tarawa (LHA-1), began on 15 November 1971, and she was commissioned into the Navy on 29 May 1976. The last of the five ships, the USS Peleliu (LHA-5), was completed on 3 May 1980.

Decommissioning and replacement
The Tarawas began leaving service in 2005. By 2011, four of the five amphibious assault ships had been decommissioned, leaving only Peleliu in active service.

The Tarawa class is to be replaced by the America class amphibious assault ship. The first America class vessel is scheduled to be delivered in 2013. Originally, four were planned (with the Wasp class USS Makin Island (LHD-8) built as a direct replacement for Belleau Wood), but the number has since been reduced.