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Significance of Auxiliary Ship

Auxiliary Ship
Auxiliary Ship IMG


An auxiliary ship refers to a naval vessel specifically crafted to provide support for combatant ships and various naval missions. While auxiliary ships may possess some limited combat capabilities, these are typically intended for self-defense, rather than serving as primary combat vessels.

Auxiliary ships hold immense significance for naval forces of all scales, as they provide essential support without which the primary fleet vessels would be left without assistance. Consequently, virtually every navy maintains a substantial fleet of auxiliary ships. However, the composition and scale of these auxiliary fleets fluctuate depending on the specific characteristics of each navy and its primary objectives.

Smaller coastal navies typically possess modest auxiliary vessels that primarily serve littoral and training support roles. In contrast, larger blue-water navies often boast expansive auxiliary fleets comprised of extensive, long-range fleet support vessels designed to offer assistance far beyond their territorial waters.


Auxiliary ships play a pivotal role in directly supporting fleet operations through a range of vital functions, with one of the most crucial being underway replenishment, also known as "replenishment at sea." This strategic maneuver enables the fleet to maintain its position without the need to return to port, as replenishment vessels transport essential supplies, including fuel, ammunition, food, and provisions, from shore to the fleet's operating location.

Oilers, often referred to as "replenishment tankers," are specialized vessels tailored for delivering fuel oil to the fleet, ensuring that naval units have the energy they need to continue their missions. In earlier times, colliers fulfilled a similar function, supplying coal to steam-powered ships.

Further enhancing fleet support are specific-role replenishment vessels, including combat stores ships, depot ships, general stores issue ships, and ammunition ships, each designed to cater to distinct supply needs.

Tenders represent yet another category of auxiliary ships. These vessels are purpose-built to provide support to smaller naval units, such as submarines, destroyers, and seaplanes, offering a mobile operational base for these units. The various types of tenders, including destroyer tenders, submarine tenders, seaplane tenders, and torpedo boat tenders, play a crucial role in ensuring the readiness and effectiveness of these smaller naval forces.


The effective support of front-line operating bases demands substantial transportation capacity, and this requirement is met through a variety of specialized auxiliary ships.

Transport ships, frequently repurposed merchant vessels or newly commissioned as APA, APD, APH, APV (often denoted with naval jargon), are essential in naval service. They play a pivotal role in transporting cargo, not only for naval support but also for all branches of a nation's military, designated by designations like AK, AKA, AKN, AKR, and AKS. Troopships and attack transports, for example, are instrumental in conveying a large number of soldiers to operational theaters.

Tankers are another vital category, designed specifically to transport fuel to forward locations, ensuring that the necessary energy resources reach the front lines.

Some transport ships exhibit remarkable specialization, as seen in the case of ammunition ships employed by the US Navy. These vessels are engineered to safely transport and supply ammunition to naval forces.

Large ocean tugs, recognized by designations like AT, ATO, ATF, ATA, and ATR (often denoted with naval jargon), have the important role of towing sizable auxiliary ships, such as barges, floating repair docks, floating cranes, and even disabled vessels, across open seas. Their capabilities are crucial for the mobility and effectiveness of naval support operations.


The capability to repair ships at sea or in conflict zones holds significant importance as it expedites the return of these vessels to operational service and enhances the chances of survival for ships severely damaged in battle. Repair vessels, often identified by designations like AR, ARB, ARC, ARG, ARH, ARL, and ARV (often referred to using naval jargon), encompass a diverse range of specialized units tailored to meet the repair needs of naval forces.

Among these vessels are small equipment ships known as Auxiliary repair docks, which provide essential repair services to smaller naval units and equipment. On the larger scale, there are Auxiliary floating drydocks, capable of accommodating more substantial naval vessels, and offering critical repair and maintenance facilities.

In addition to these, there are Aircraft repair ships that specialize in the repair and maintenance of naval aircraft. These vessels play a crucial role in ensuring the continued operational readiness of naval aviation assets, making them an indispensable part of naval support operations.

Harbor Support

Harbor support plays a pivotal role in naval operations, encompassing various types of vessels that contribute to the efficient functioning of port facilities. These vessels include tugboats, barges, lighter barges, derrick-crane vessels, and others, all essential for the movement of ships and equipment within the harbor.

Depot ships and tenders are also a crucial part of harbor support, providing servicing and maintenance for ships currently stationed in the harbor, ensuring their readiness for future operations.

Furthermore, these harbor support vessels play a vital role in maintaining the harbor itself. They contribute to the upkeep of channels by dredging, ensure the stability of jetties and the proper positioning of buoys, and can even serve as floating platforms for port defenses when necessary.

In the US Navy, tugboats are classified as type YT, YTB, YTM, YTL, or a Type V ship, while barges are designated as a Type B ship or YF, YFN, YFR, or YFRN, with each type serving specific functions within the harbor support infrastructure.

Further Support

Auxiliary ships play a diverse and crucial role in naval operations, each type serving a specific function within the fleet. Here’s an overview of some key types of auxiliary ships:

1. Radar Picket Ships: These vessels are designed to increase radar detection range around a naval force, enhancing early warning capabilities and situational awareness.

2. Communications Relay Ships (AGMR): Floating communications stations, AGMR ships facilitate efficient and secure communication within and beyond the fleet, ensuring the flow of critical information.

3. Tracking Ships or Range Instrumentation Ships (AGM): Equipped with advanced antennas and electronics, AGM ships support the launching and tracking of missiles and rockets during testing and training exercises.

4. Command Ships (AGF): Serving as flagships for fleet commanders, AGF ships provide a centralized command and control platform for coordinating naval operations.

5. Wind-Class Icebreakers (AGB WAGB): These support ships are crucial for operations in icy waters, helping to clear paths for other vessels and ensure access to remote regions.

6. Rescue and Salvage Ships and Submarine Rescue Ships (ASR): These ships are vital for surface and submarine rescue operations, providing support and resources to recover personnel and vessels in distress.

7. Barracks Ships or Auxiliary Personal Living Ships (APL): APL vessels, often in the form of barges, provide living quarters for service personnel, ensuring they have suitable accommodations while stationed in remote or temporary locations.

Each type of auxiliary ship serves a unique purpose, contributing to the overall effectiveness and versatility of naval operations.


The utilization of various types of vessels, such as Technical Research Ships (AGTR), Tracking Ships (AGM), Environmental Research Ships (AGER), Hydrofoil Research Ships (AGEH), and Survey Vessels, serves a multifaceted purpose within naval operations. These ships are primarily tasked with enhancing a navy’s comprehension of its operating environment and aiding in the experimentation and assessment of new technologies for potential integration into other naval vessels.

1. Technical Research Ships (AGTR): AGTR vessels are instrumental in conducting technical research and gathering data, often related to communication and electronic intelligence, to support naval intelligence efforts and improve the navy’s understanding of electronic environments and communication systems.

2. Tracking Ships (AGM): AGM ships are equipped with advanced tracking systems and technologies to monitor and record the flight paths and performance of missiles, rockets, or other projectiles during testing and evaluation, contributing valuable data for research and development.

3. Environmental Research Ships (AGER): AGER vessels are tailored for environmental research, enabling the collection of data related to oceanographic and environmental conditions. This information is critical for naval planning, including submarine operations and underwater surveillance.

4. Hydrofoil Research Ships (AGEH): AGEH ships are designed to explore and assess the potential applications and benefits of hydrofoil technology in naval vessels. These vessels contribute to the development of faster and more efficient naval platforms.

5. Survey Vessels: Survey vessels are essential for mapping and charting the seafloor, coastal areas, and other water bodies. They provide critical hydrographic data for navigation, infrastructure development, and maritime safety.

These research and survey vessels play a crucial role in advancing naval capabilities by enhancing knowledge of the operating environment, evaluating cutting-edge technologies, and contributing to the overall effectiveness of naval forces.

Hospital Ships

Hospital ships are able to provide medical care in remote locations to personnel.

Not classified auxiliary ship

The US Navy has utilized an unclassified miscellaneous auxiliary ship classification known as IX. This classification is assigned to ships that do not fall into standard categories, including new ships that have not yet been assigned a classified role, vessels that have been removed from their previous classifications, or those that simply do not fit into established naval categories. This classification allows for flexibility in categorizing and managing ships that do not fit neatly into predefined roles or designations.


  1. Ship Abbreviations and

  2. Navy Ships: Turning Over Auxiliary Ship Operations to the Military Sealift Command Could Save

  3. "Submarine Tenders (AS)". Retrieved 2019-01-23.

  4. "Other Auxiliaries(AGB, AGC, AGDS, AGEH, AGER, AGF, AGM, AGMR, AGP, AGR, AGTR)". Retrieved 2019-01-23.

  5. "Royal Fleet Auxiliary ship makes last Plymouth call". BBC News. 2011-02-01. Retrieved 2021-09-18.

  6. "Ocean Tugs (AT, ATO, ATF, ATA, ATR)". Retrieved 2019-01-23.

  7. "Oilers AO". Retrieved 2019-01-23.

  8. "Combat Logistics Resupply Ships AC AE AF AFS AKE AOE AOR". Retrieved 2019-01-23.

  9. "Cargo Ships AK AKA AKN AKS". Retrieved 2019-01-23.

  10. "Gasoline Tankers AOG". Retrieved 2019-01-23.

  11. "Destroyer Tenders AD". Retrieved 2019-01-23.

  12. "Aviation Support Ships AV AVP AVS". Retrieved 2019-01-23.

  13. "Miscellaneous Auxiliaries AG". Retrieved 2019-01-23.

  14. "Troop Transports (AP)". Retrieved 2019-01-23.

  15. "Attack and Other Transports (APA, APD, APH, APV)". Retrieved 2019-01-23.

  16. "Floating Dry-Docks (AFDB, AFDM, AFDL, ARD, ARDM, YFD)". 30 April 2015. Retrieved 8 January 2019.

  17. "Yard Tugs Wartime YT YTB YTM YTL". Retrieved 2019-01-23.

  18. "Freight Lighters Wartime YF YFN YFND YFR YFRN YFRT". Retrieved 2019-01-23.

  19. "Other Auxiliaries AGB, AGC, AGDS, AGF, AGM, AGMR, AGP, AGR". Retrieved 2019-01-23.

  20. Custodio, Jonathan. "U.S. transport ship and field hospitals heading to Haiti for quake relief". POLITICO. Retrieved 2021-09-18.


  22. Unclassified auxiliary ships

  23. Unclassified (IX): Special


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