Auxiliary ship

Anauxiliary shipis anaval shipdesigned to supportcombatant shipsand other naval operations.Auxiliary ships are not primary combatant vessels, though they may have some limited combat capacity, usually for purposes of self-defense.
Auxiliary ships are extremely important fornaviesof all sizes because if they were not present the primary fleet vessels would be unsupported. Thus, virtually every navy maintains an extensive fleet of auxiliary ships, however, the composition and size of these auxiliary fleets vary depending on the nature of each navy and its primary mission. Smaller coastalnaviestend to have smaller auxiliary vessels focusing primarily on littoral and training support roles, while largerblue-water naviestend to have larger auxiliary fleets comprising longer-range fleet support vessels designed to provide support far beyondterritorial waters.
One of the most direct ways that auxiliary ships support the fleet is by providingunderway replenishment(also known as "replenishment at sea") to major fleet units. This allows the fleet to remain in the same location, with the replenishment vessels bringing up fuel,ammunition, food, and supplies fromshoreto the fleet wherever it is operating.
Oilers("replenishment tankers") are vessels specifically designed to bring fuel oil to the fleet, while the earlierCollierssupplied coal-burningsteamships. Specific role replenishment vessels includecombat stores ships,depot ships,general stores issue ships, andammunition ships.
Tendersare specifically designed to support a type of smaller naval unit, likesubmarines,destroyers, andseaplanes, providing a mobile base of operations for these units: specificallydestroyer tenders,submarine tenders,seaplane tenders,torpedo boat tenders.
Supporting front-line operating bases requires immense transportation capacity.  Transport ships are often convertedmerchant shipssimplycommissioned(APA, APD, APH, APV)into naval service.Tankersare transports specifically designed to ship fuel to forward locations. Transport ships are often employed not only carrying cargo for naval support but are in support of all forces of a nation's military (AK, AKA, AKN, AKR, AKS). In particular,troopshipsandattack transportsare used to carry a large number of soldiers to operational theatres. Some transport ships are highly specialized, like theammunition shipsemployed by the US Navy.Large ocean tugs (AT, ATO, ATF, ATA, ATR)are used to tow large auxiliary ships, like barges, floating repair docks, and floating cranes in the open sea, also disabled ships.
Repairing ships at sea or in conflict areas is important as it allows these vessels to return to service more quickly, while also increasing the chance of survival for ships critically damaged in battle.Repair vessels(US Navy: AR, ARB, ARC, ARG, ARH, ARL, ARV)range from small equipment ships known asAuxiliary repair docks, to the largerAuxiliary floating drydocks, there are alsoAircraft repair shipsthat specialize in repair ofnaval aircraft.
Harbor support is a critical support role, with various types of vessels includingtugboats,barges,lighter barges,derrick-crane vessels, and others used to move ships and equipment around the port facilities, anddepot shipsand tends to service ships currently in the harbor. These vessels also help maintain the harbor by dredging channels, maintainingjettiesandbuoys, and even providing floating platforms for port defenses.
In US Navy, tugboats are type YT, YTB, YTM, YTL or aType V ship.and barges are classified as aType B shipor YF, YFN, YFR, or YFRN.
Radar picketto increase the radar detection range around a force.Communications Relay Ships(AGMR) are floating communications stations.Tracking shipsor Range Instrumentation Ships (AGM) are equipped with antennas and electronics to support the launching and tracking of missiles and rockets.Command ship(AGF) are flagships of the commander of a fleet.Wind-class icebreaker(AGB WAGB) are support ships.Rescue and salvage shipandSubmarine rescue ship(ASR) for surface support ship for ship and submarine rescue.Barracks shipsor Auxiliary Personal Living ships, (APL) are vessels-barges for service men to live on.
A wide variety of vessels are employed asTechnical Research Ships(AGTR),Tracking Ships(AGM),Environmental Research Ships (AGER),Hydrofoil Research Ships (AGEH), andSurvey Vessels, primarily to provide a navy with a better understanding of its operating environment or to assist in testing new technologies for employment in other vessels.
Hospital shipsare able to provide medical care in remote locations to personnel.
TheUS Navyalso used an unclassified miscellaneous auxiliary ship classification in which the unclassified miscellaneous auxiliary ship classification isIX. An unclassified miscellaneous auxiliary ship can be a new ship without a classified role or a ship that does not fit into a standard category or a ship that had been removed from its classification.