Replenishment oiler

One of the first generation of "blue-water" navy oiler support vessels was the British RFA Kharki, active 1911 in the run-up to the First World War.

During the Second World War, the United States Navy's dramatically enlarged fleets, especially those in the Pacific Theater, required massive quantities of black oil, diesel oil, avgas, and other fuels and lubricants to support American land, sea, and air operations against remote, widely dispersed Japanese forces.

Those supply demands resulted in U.S. Navy personnel refining many established practices for oilers and creating new procedures for replenishing warships while underway and for transporting highly combustible materials with increased effectiveness through hostile waters and over vast ocean distances.

[2][3] Modern examples of the fast combat support ship include the large British Fort class, displacing 31,066 long tons (31,565 t) and measuring 669 feet (204 m) in length and the United States' Supply-class USNS Arctic, which displaces 48,800 long tons (49,600 t) and has an overall length of 754 feet (230 m).

Such ships are designed to carry large amounts of fuel and dry stores for the support of naval operations far away from port.

[5] Up through the Second World War Navy oilers used commercial tanker hulls, with the addition of UNREP gear, defensive guns, and military electronic and damage-control equipment; since the 1950s however they have been built from the keel up as specialized naval auxiliaries.

[7] Since the 1960s the classification Transport Oiler (AOT) has applied to tankers which ship petroleum products to depots around the world, but do not engage in UNREP.