Replenishment oiler
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A replenishment oiler is a naval auxiliary ship with fuel tanks and dry stores capability, which can replenish other ships underway.
The US Navy hull classification symbol for this type of ship is AOR. Classes include the Wichita-class ships of the US Navy, the Soviet/Russian Boris Chilikin type, and the Canadian Protecteur class. They are slower and carry fewer dry stores than Fast Combat Support Ship (AOE) ships.
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[edit] Overview
The US Navy Wichita class of AORs comprises seven ships. The class ship was commissioned in 1966, and the last ship, the USS Roanoke, was commissioned in 1976. The naming convention for these ships was that they be named for smaller US cities which have rivers of the same name. All ships of this class have been retired from service, and are being held by MARAD in the inactive ("mothball") fleet (National Defense Reserve Fleet, a.k.a. NDRF).
[edit] History of design
The forerunner of this design was a Kriegsmarine (German Navy) ship, the Dithmarschen, which was built in 1938. The Dithmarschen was designed to provide fuel and stores (including munitions) in a "One Stop Shopping At Sea" context to the German fleet. After the World War II she was claimed by the United States as a war prize and commissioned into the United States Navy as the USS Cohecuh (AOR-110). She proved the feasibility of this sort of vessel in supporting task forces at sea. She was decommissioned in 1956. The Wichita class was one variant on this concept later developed by the U.S. Navy, the other variant being the larger and faster AOE class of fleet replenishment oiler.
[edit] Characteristics of US AOR design
The modern US AOR-1 class of ships was designed primarily to support anti-submarine task forces. These ships gross just under 40,000 tons, have a length of 651 feet (198 m), a beam of 96 feet (29 m), and a draft of about 35 feet (10.7 m) fully loaded. They are equipped with highly automated fuel and cargo handling systems, and are capable of underway replenishment (UNREP in Navy terminology) from both port and starboard sides simultaneously, and also can transfer stores and munitions by helicopter (vertical replenishment or VERTREP). The ship's complement was 34 officers and 463 enlisted.
[edit] Armament
These vessels are support vessels, not combat units. As delivered by the shipyards they were equipped with two 5"/38 guns (five inch, 38 calibre), located aft on the 02 level. This is illustrated by the photo of the USS Wabash (AOR-5) shown above. However, as each ship was drydocked for maintenance, the guns were removed and replaced with a helicopter hangar, and the ships were equipped with two CH-46 Sea Knight helicopters, two Phalanx CIWS close-in weapons systems and one Mk-29 Sea Sparrow point defence system.
[edit] Ship layout
These vessels have two superstructures. The forward superstructure houses the bridge, a Combat Information Center (CIC), the Captain's quarters, various support facilities, and the pilot house. The after superstructure houses the crew's quarters, various support facilities, the helicopter deck, and a centerline elevator extending from the main deck to the 02 level for use in material (VERTREP) transfer.
These ships are unusual for naval vessels in that the fire room is aft of the engine room, and the shafts extend through the fire room and the steering engine room. From aft forward, the engineering spaces consist of the steering engine room, the fire room, and the engine room. The forward bulkhead of the engine room abuts onto cargo tanks. All boilers are in the single fire room, and both engines are in the single engine room. There are two hydraulic steering engines in the steering engine room, controlled either locally by a trick wheel or by the helmsman in the pilot house. They are powered by three Foster-Wheeler D-type steam generators operating at 600 PSI, driving two engines with a combined power output of 33,000 SHP (shaft horsepower), giving them a maximum sustained speed of about 22 knots. They are equipped with twin rudders. The plant auxiliary machinery is all electric, and they are equipped with four 2,000 KW electric generators. There are two deck elevators on the main deck, and they can accommodate a large amount of dry cargo, including refrigerated and frozen stores, on the second deck. They have two pump rooms for fuel transfer, and commonly transfer Navy Distillate (ND), Number 2 diesel fuel, and JP-5 They also carry and transfer aviation gasoline, for which a separate pump room, set of tanks, and transfer facility is located on the forecastle (foc'sul). The US Navy will as a matter of policy neither confirm nor deny that these ships are equipped for the storage and transfer of nuclear weapons.
[edit] AOR class ships in other navies
The British Royal Fleet Auxiliary operates 2 AOR-type ships of the Fort Victoria class to support the Royal Navy. Navies other than the U.S. Navy are actively designing and building fleet replenishment oilers of the AOR class. These navies, including the Royal Australian Navy and the Spanish Navy, have requirements that do not include high speed and high capacity; thus an AOR design meets the logistics needs of these navies better than would a larger, faster AOE design.
