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Replenishment At Sea (RAS)

Despite having a network of re-supply and refueling stations, the Royal Navy wanted the facility to refuel and resupply its ships while at sea, and this was initially carried out with stores and bags of coal passed from the stern of the supply ship to the bow of the warship by a system of ropes and blocks. Later, techniques were developed for the transfer of fuel oil, still using the astern method, but with oil pumped over through a flexible bronze hose.

It was not until the Second World War that Replenishment At Sea (RAS) became well established. One of the principal problems in abeam refuelling was the suction effect caused by the interaction of the bow waves of the two vessels. This caused the vessels to be drawn together. In 1942 two German tankers, whose task was to replenish the battleship Bismarck, were captured with all their equipment. These were closely studied and the Admiraly was greatly impressed, especially by the use of rubber hoses which were found to be vastly superior to the bronze hoses the RFA had used up to then. However, due to the shortage of materials, the changeover could not be undertaken immediately. The German method of transferring fuel in rubber hoses was eventually adapted, and experience, particularly gained from Pacific operations, led to the abeam method of fuel replenishment and the heavy jackstay method for transfer of stores. Today, replenishment at sea is a routine operation, carried out from RFA ships in operations, exercises and deployments throughout the world. It remains, nevertheless, an evolution calling for the highest standards of seamanship as the ships sail in close proximity, linked together, in daytime or at night and in all weathers.

The two fleet support tankers, RFA's Bayleaf and Orangeleaf were all built as commercial tankers, but underwent conversion to bring them to RFA standards and equip them for naval support when they entered RFA service. One of this class is normally based permanently in the Gulf to support the Royal Navy's Armilla Patrol ships. The two small fleet tankers, RFA's Black Rover and Gold Rover complete the tanker fleet.

These ships, too, are normally deployed away for long periods, one to support the Falkland Islands Guard ship the other normally undertaking FOST (Flag Officer Sea Training) duties. RFA's Fort Victoria and Fort George are combined fleet support tanker and stores ships, designed to give "one-stop" support to naval task groups. Large ships of 31,500 tonnes displacement, they are able to supply both fuel and stores to ships at sea.

The other two Fort class ships, RFA's Fort Austin and Fort Rosalie, are fleet support stores ships to replenish warships with stores such as food, spare parts and ammunition.

All tankers and stores ships, with the exception of the Leaf-class, have large flight-decks, hangars and facilities to embark helicopters. These are used to carry out re-supply by transferring underslung loads, but can also operate from the RFA's as anti-submarine or troop carriers, thus making the RFA ships "force multipliers". In the 1998 Gulf crisis, both Fort George and Fort Victoria carried 5 helicopters with all their crews and support staff on a permanent basis.

The maintenance periods undertaken by Royal Fleet Auxiliary oilers in each year since 1997 that have included a period in dry dock are shown in the following table.

The time in dry dock is only ever a part of the overall maintenance period and details of the exact time each vessel spent in the dock are not held centrally and could be provided only at disproportionate cost. In addition to the routine maintenance shown in the table RFA Grey Rover was docked in 1997 to undertake an emergency repair.