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 to Auxiliary repair docks, and larger Auxiliary floating drydock. Aircraft repair ships specialized in repair of naval aircraft. Harbor Harbor support is a critical support role, with various types of vessels including tugboats, barges, lighter barges, derrick-crane vessels, and others used to move ships and equipment around the port facilities, and depot ships and tends to service ships currently in the harbor. These vessels also help maintain the harbor by dredging channels, maintaining jetties and buoys, and even providing floating platforms for port defenses. In US Navy, tugboats are type YT, YTB, YTM, YTL or a Type V ship. and barges are classified as a Type B ship or YF, YFN, YFR, and YFRN. Support Radar picket to increase the radar detection range around a force. Communications Relay Ships (AGMR) are floating communications stations. Tracking ship or Range Instrumentation Ship (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 ship and Submarine rescue ship (ASR) for surface support ship for ship and submarine rescue. Barracks ship or Auxiliary Personal Living, (APL) are vessels-barges for service men to live on. Research A wide variety of vessels are employed for research(AGTR) (AGM), Environmental Research Ships (AGER), Hydrofoil Research Ships (AGEH) and survey, 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 Hospital ships are able to provide medical care in remote locations to personnel. Unclassified auxiliary ship The US Navy also used an unclassified miscellaneous auxiliary ship classification. The unclassified miscellaneous auxiliary ship classification is IX. 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. See also List of auxiliaries of the United States Navy List of auxiliary ship classes in service Service Squadron US Naval Advance Bases References Notes Bibliography External links Ship types