Replenishment oilers

Replenishment oiler

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.

History of design

The forerunner of the replenishment oiler 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). The ship proved the feasibility and flexibility of this sort of vessel in supporting task forces at sea. The ship was decommissioned in 1956. The United States Navy then designed 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.

Characteristics of an AOR

For smaller navies, such as the Canadian Navy, the AOR are typically one of the largest ships in the navy. Such ships are designed to carry large amounts of fuel and dry stores for the support of naval operations far away from port. Replenishment oilers are also equipped with more extensive medical and dental facilities than smaller ships can provide.

Such ships are equipped with multiple refueling gantries to refuel and resupply multiple ships at a time. The process of refueling and supplying ships at sea is called underway replenishment. Furthermore, such ships often are designed with helicopter decks and hangars. This allows the operation of rotary-wing aircraft, which allows the resupply of ships by helicopter. This process is called vertical replenishment. Furthermore, such ships, when operating in concert with surface groups, can act as the aviation maintenance platform where helicopters receive more extensive maintenance that can be provided by the smaller hangars of the escorting ships.

Armament

Because the replenishment oiler is not a combat unit, rather a support vessel, such ships are often lightly armed, usually with self-defense systems (such as the Phalanx CIWS close-in weapons systems), small arms, machine guns and/or light automatic cannons. They may also carry man-portable air-defense systems, or MANPADS, for additional air defence capability.

AOR class ships in other navies

The French Navy operates 4 AOR-type ships of the Durance class. Several sister-ships of this class have been sold to Argentine Navy (ARA Patagonia), Royal Australian Navy (HMAS Success) and a smaller version to Saudi Navy (Boreida, Yunbu). 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.