A replenishment oiler or replenishment tanker is a naval auxiliary ship with fuel tanks and dry cargo holds which can supply both fuel and dry stores during underway replenishment (UNREP) at sea. Many countries have used replenishment oilers.
The United States Navy's hull classification symbol for this type of ship was 'AOR' (Auxiliary Oil Replenishment). Replenishment oilers are slower and carry fewer dry stores than the US Navy's modern fast combat support ships, which carry the classification 'AOE'. In 2020 the US Navy began to develop a new type of ship, the 'AOL' or light replenishment oiler; construction of the first is planned for 2026. [1]
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. [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).
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 Durance class, this capability being built into the vessels from the start.
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.
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. [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. They were previously classified as Fleet Oilers [6] in the 20th century; under the current MSC operation their full classification is listed as Fleet Replenishment Oilers. [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.
The first fleet oilers [8] were identified by the hull designation AO, which is still in use. [7] Large, fast multifunction oilers which also provide ammunition and dry stores are identified as Fast Combat Support Ships (AOE), [9] 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).
There are three classes of vessels currently in commissioned service:
Both the Henry J. Kaiser-class and Supply class will be replaced by the John Lewis-class ships.
The fast combat support ship is a type of replenishment auxiliary ship. Different from traditional logistic ships, the fast combat support ship is designed with high speed to keep up with the carrier battle group/carrier strike group, while the multi-product station is capable of supplying all types of necessities for the fleet.
The Military Sealift Command (MSC) is an organization that controls the replenishment and military transport ships of the United States Navy. Military Sealift Command has the responsibility for providing sealift and ocean transportation for all US military services as well as for other government agencies. It first came into existence on 9 July 1949 when the Military Sea Transportation Service (MSTS) became solely responsible for the Department of Defense's ocean transport needs. The MSTS was renamed the Military Sealift Command in 1970.
The Protecteur-class auxiliary oiler replenishment (AOR) ships were used by the Royal Canadian Navy to resupply ships at sea with food, munitions, fuel and spare parts. They had more sophisticated medical and dental facilities than smaller warships. At 172 metres (564 ft) the ships were some of the largest operated by the RCN. Entering service in 1969, the last vessel of the class was paid off in 2016.
Underway replenishment (UNREP) or replenishment at sea (RAS) is a method of transferring fuel, munitions, and stores from one ship to another while under way. First developed in the early 20th century, it was used extensively by the United States Navy as a logistics support technique in the Pacific theatre of World War II, permitting U.S. carrier task forces to remain at sea indefinitely.
A joint support ship (JSS) is a multi-role naval vessel capable of launching and supporting joint amphibious and airlift operations. It can also provide command and control, sealift and seabasing, underway replenishment, disaster relief and logistics capabilities for combined land and sea operations.
An auxiliary ship is a naval ship designed to support combatant ships and other naval operations. Auxiliary ships are not primary combatant vessels, though they may have some limited combat capacity, usually for purposes of self-defense.
The Cimarron-class oilers were an underway replenishment class of oil tankers which were first built in 1939 as "National Defense Tankers," United States Maritime Commission Type T3-S2-A1, designed "to conform to the approved characteristics for naval auxiliaries in speed, radius and structural strength", anticipating their militarization in the event of war. "Tentative plans had been reached with the Standard Oil Company of New Jersey to build ten high-speed tankers with the government paying the cost of the larger engines needed for increased speed. By the first week in December [1937], Standard Oil had solicited and received bids from a number of yards providing for the construction of a number of 16,300-ton (deadweight) capacity tankers. Bids were requested for two versions: a single-screw design of 13 knots and a twin-screw design of 18 knots. The price difference between the two would be used to establish the government's cost subsidy for greater speed. Plans and specifications for both designs were prepared for Standard Oil by naval architect E. L. Stewart. It seems certain that the design for the 18-knot tanker evolved out of the bureau's (C&R) design for a fleet oiler."
USS Conecuh (AOR-110) was a fleet replenishment tanker, originally built by F. Schichau, Danzig, in 1938 as a combination oiler and supply vessel or "Troßschiff" for the Kriegsmarine and christened as Dithmarschen. Taken over by British authorities at Bremerhaven when World War II ended, Dithmarschen was allocated to the United States Navy on 15 January 1946 by the Inter-Allied Reparations Commission.
Service Force, United States Pacific Fleet, usually known as COMSERVPAC, was a service support command of the United States Pacific Fleet from 1942 until 1973. It was the reincarnation of the former Base Force. The Service Force comprised the supply train of the fleet which includes Oilers (AO), Gasoline Tanker (AOG), Repair Ships (AR), Ammunition Ships (AE), Destroyer Tenders (AD) and Submarine tenders (AS).
The Sacramento-class fast combat support ships were a class of four United States Navy supply ships used to refuel, rearm, and restock ships in the United States Navy in both the Atlantic and Pacific Oceans.
Wichita-class replenishment oilers comprised a class of seven replenishment oilers used by the United States Navy from the late 1960s to the mid-1990s. The ships were designed for rapid underway replenishment using both connected replenishment and vertical replenishment.
USNS Henry J. Kaiser (T-AO-187) is a United States Navy fleet replenishment oiler and the lead ship of her class. Her mission is to resupply U.S. Navy and allied ships at sea with fuel oil, jet fuel, lubricating oil, potable water, and dry and refrigerated goods, including food and mail.
USNS Supply (T-AOE-6), ex-USS Supply (AOE-6), is the lead ship of the Supply-class fast combat support ships. She was commissioned in 1994 and decommissioned in 2001, after which she was transferred for service with the U.S. Military Sealift Command.
The United States Navy Combat Logistics Force (CLF), formerly the Naval Fleet Auxiliary Force (NFAF), is a subordinate component of the United States Navy's Military Sealift Command. CLF's 42 ships are the supply lines that provide virtually everything that Navy ships at sea needs to accomplish its missions, including fuel, food, ordnance, spare parts, mail and other supplies. NFAF ships enable the Navy fleet to remain at sea, on station and combat ready for extended periods of time. CLF ships also conduct towing, rescue and salvage operations or serve as floating medical facilities. All CLF ships are government owned and crewed by civil service mariners. Some of the ships also have a small contingent of Navy personnel aboard for operations support, supply coordination and helicopter operations.
The T3 tanker, or T3, are a class of seaworthy large tanker ships produced in the United States and used to transport fuel oil, gasoline or diesel before and during World War II, the Korean War and the Vietnam War. The T3 tanker classification is still used today. The T3 tanker has a full load displacement of about 24,830 tons.
The Tide-class tanker (formerly the Military Afloat Reach and Sustainability (MARS) project) is a class of four fast fleet tankers that entered service with the British Royal Fleet Auxiliary from 2017. The 37,000 t ships provide fuel, food, fresh water, ammunition and other supplies to Royal Navy vessels around the world. Norway ordered a similar 26,000 t version with a 48-bed hospital and greater solid stores capacity, but reduced liquid capacity; it was delivered in November 2018 as HNoMS Maud two years after originally planned. The two classes are very similar but are not directly comparable due to large variance in capabilities delivered.
MV Asterix is a Canadian commercial container ship. It was purchased by Federal Fleet Services as part of Project Resolve, and was later converted into a supply ship for the Royal Canadian Navy (RCN). She is intended to act as an interim replacement between the out of service Protecteur-class replenishment oiler and the future Protecteur-class auxiliary vessel. Originally launched in Germany in 2010 as Cynthia, the ship was converted and delivered to the RCN in December 2017 when she will be leased to the navy with a merchant navy crew, complemented by RCN personnel. Asterix will be in Canadian service well into the 2020s.
The Supply class is a class of replenishment oilers of the Royal Australian Navy, a role that combines the missions of a tanker and stores supply ship. As such they are designated auxiliary oiler replenisher (AOR). They are tasked with providing ammunition, fuel, food and other supplies to Royal Australian Navy vessels around the world. There are two ships in the class, Supply and Stalwart. The project is expected to cost anywhere between $1 and $2 billion. Navantia were selected to build a design based on the Spanish Navy's current replenishment vessel Cantabria, which entered service in 2011.
The Next-Generation Logistics Ship (NGLS) is a programme being undertaken by the United States Navy to construct a fleet of medium-sized auxiliary ships that will provide underway replenishment (UNREPS), disaster relief and logistics capabilities for combined land and sea operations. These new vessels are not intended to replace existing classes such as the John Lewis-class replenishment oilers (AO) and the Supply-class fast combat support ships (AOE) but to supplement their operations, especially in littoral waters and combat zones where larger vessels cannot be risked.