Replenishment oiler

frigates and . The development of the "oiler" paralleled the change from coal- to oil-fired boilers in warships. Prior to the adoption of oil fired machinery, navies could extend the range of their ships either by maintaining coaling stations or for warships to raft together with colliers and for coal to be manhandled aboard. Though arguments related to fuel security were made against such a change, the ease with which liquid fuel could be transferred led in part to its adoption by navies worldwide.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. Such vessels heralded the transition from coal to oil as the fuel of warships and removed the need to rely on, and operate within range of coaling stations. 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. Modern examples of the fast combat support ship include the large British Fort class, displacing and measuring in length and the United States' , which displaces and has an overall length of . ==Characteristics==

For all but the largest navies, replenishment oilers are typically one of the largest ships in the fleet. 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. These ships, when operating in concert with surface groups, can act as an aviation maintenance platform where helicopters receive more extensive maintenance than can be provided by the smaller hangars of the escorting ships. Their size, additional facilities, and ability to support the operation of other vessels, means that replenishment oilers have been used as command ships, with some ships, such as the French , this capability being built into the vessels from the start. ==Armament==

Because the replenishment oiler is not a combat unit, but 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 for additional air defense capability. ==Operators==

• operates ARA Patagonia • operates two s. • operates • operates . • operates Almirante Montt and • operates two Fuyu-class fast combat support ships, four Dayun-class general stores issue ships, nine Fuchi-class replenishment ships, and a single Fusu-class replenishment ship. • operates and ROCS Panshih • operates two s, purchased from Germany. • operates a single , purchased from Germany (being supplemented or replaced by two s, purchased from the United Kingdom). • operates two Jacques Chevallier-class and one s • operates six s, two s, and three s. • operates a single and two s, purchased from Germany. • operates two s, one , and a single . • operates a single purchased from the United Kingdom, two Tarakan-class tankers and more on order. • operates two logistic support ship, a single and a single s. • operates two s. • operates three s and two s. • operates three s, and • operates & HNLMS Den Helder • operates • operates • operates PNS Nasr and • operates BAP Tacna • operates • operates three s, one Dora-class tanker, one s, four s, three s, two s, two Project 23130 replenishment oilers, four Project 03180 replenishment oilers, and a single Project 03182 replenishment oiler. • operates two s. • operates • operates and . • operates • operates two s and one Derya class. • British Royal Fleet Auxiliary operates one , four s and two s (maintained in reserve). • United States Military Sealift Command operates four s, fifteen s, fourteen s, and two s. • operates a single purchased from Germany • operates • operates the replenishment oiler HQ-905 Former operators • decommissioned in 2020. • decommissioned in 2020. Two new Luís de Camões-class vessels under construction. • decommissioned its only in 2001. ==United States Navy oilers==

In the United States Navy, an Oiler is a Combat Logistics ship that replenishes other ships with fuel and in some cases food, mail, ammunition and other necessities while at sea, in a process called Underway Replenishment or UNREP. 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. They were previously classified as Fleet Oilers in the 20th century; under the current MSC operation their full classification is listed as Fleet Replenishment Oilers. 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. The first fleet oilers were identified by the hull designation AO, which is still in use. and mid-size ones Replenishment Oilers (AOR). The AOR designation is no longer in use. All of these oilers provide the combined services of the AO, AE, AFS and AK. The style "USNS" and prefix "T" identify a ship as being operated by a civilian crew under the Military Sealift Command (known as the Military Sea Transportation Service until 1970). Current classes There are three classes of vessels currently in commissioned service: • , T-AO-187-T-AO-204, in service 1986 • , T-AOE, in service 1990 • , T-AO-205-T-AO-221, in service 2022 Both the Henry J. Kaiser and Supply classes will be replaced by the John Lewis-class ships. ==References==