AS Submarine Support
ASL Submarine Tender
ASR Submarine Rescue

These ships are designated as a submarine support ship (qián ting zhi yuán jiàn in Chinese). Auxiliary vessels used in the navies of the world in a variety of special functions as logistical support units for combat units. For a case of conflict, there are also support vessels in the form of armed and for example equipped with helicopters merchant ships. Submarine tenders are specially configured to provide intermediate-level maintenance support to deployed and non-deployed forces. They have full intermediate-level repair capability in the hull, mechanical, and electrical repair areas and have extensive battle-damage repair capabilities. These ships typically provide their support services from relatively secure ports or anchorages, with the tended forces coming to their location.

A related but distinct type of ship is the submersible-support research vessel performing submersible vehicle launch and recovery. Typical applications undertaken by the vessel included submersible/remotely operated vehicle (ROV) support, large towed systems support, deployment and retrieval of moored devices, surface oceanographic/hydrographic applications, and diving support.

Remotely operated underwater vehicles (ROVs) are unoccupied, highly maneuverable underwater robots operated by a person aboard a surface vessel. They are linked to the ship by a group of cables that carry electrical signals back and forth between the operator and the vehicle. Most are equipped with at least a video camera and lights. Additional equipment is commonly added to expand the vehicle’s capabilities. These may include a still camera, a manipulator or cutting arm, water samplers, and instruments that measure water clarity, light penetration, and temperature.

A variety of support ships with hoisting apparatuses have been used and proposed for docking and recovering research submersibles by a surface vessel. Some of these use no more than a conventional surface vessel provided with a crane. The arrangement is not totally satisfactory since the relative motions between the submersible and the support vessel create excessive acceleration forces during the lifting or lowering of the submersible. These forces batter the submersible and crewmen alike. Another hazard is that the possibility of collision is ever present because one vessel usually is stationary while the other attempts to manuever into a recovery position. Another approach calls for docking the submersible onto a submerged platform or submarine. The trouble here, however, is that the submerged recovery platform is uncontrollable. That is to say, when the submerged recovery platform does not extent through the water-air interface nor does it rest on the bottom, it is extremely unstable. Being neutrally buoyant and at rest, it offers no resistance and does not provide counteracting forces during a launching or recovery. In addition, the submerged platform is tied to this single specific use.

Autonomous underwater vehicles (AUVs) are normally launched into the water from a surface support vessel by a simple wire hoist. The AUV does not have an umbilical, and thus there are no hard wire/live links with the vehicle, which can be used to facilitate the launch and recovery process to and from the vessel. Once an AUV has been lowered from the deck of the support vessel to the water surface, the AUV is manually released from the hoist so it can then submerge and accomplish its mission. The hoist line is manually attached to the AUV for recovery to the deck after the mission. Both launch and recovery to and from the vessel are difficult in rough weather.

Advances in oceanographic research have given rise to a need for improved submarine research vessels to support an ever expanding program in oceanography. Oceanographic studies require not only a submarine vessel capable of penetrating to the extreme depths of the ocean, but also a vessel capable of permitting a broadened and more sustained observation of the oceans bulk.

The expense associated with prior oceanographic research vessels has tended to counteract the technical advantages achieved through the use of such craft for research. Not only have the building costs incurred in the construction of previous research submarines been prohibitive, but the high costs of operational support have also contributed to the expenses of oceanographic research through the use of submarine vessels. For example, during operation it is necessary that a tender vessel be supplied to support the operation of the research craft, and the large-sized underwater research vessels previously developed have required the support of a large, expensive surface tender.

In the Great War, the US Navy began to use submarine tenders extensively as submarines became increasingly important to critical missions. American submarines underwent regularly-scheduled maintenance and overhaul at shipyards, but they were also served by submarine tenders. These "factories afloat" performed countless repair and maintenance jobs to keep the boats operational. During the Cold War, each ballistic missile submarine spent 30 days alongside a tender between patrols.

However, after the end of the Cold War, as the US Department of Defense reduced the size of its operating forces, the total number of nuclear-powered attack submarines (SSNs) reduced from a goal of one hundred in the 1980s to fewer than fifty SSNs. As a result, during the 1990s, the number of tenders reduced from ten to two: the USS Frank Cable and USS Emory S. Land. These tenders currently operate out of the ports of Apra Harbor, Guam and Diego Garcia, respectively, and furnish maintenance and logistic support for nuclear attack submarines for the Fifth Fleet area of responsibility (AOR) and Seventh Fleet AOR. These ships are capable of simultaneously mooring up to four submarines alongside the ship to conduct maintenance.

Older class submarines were designed to carry rescue buoys as an integral part of their structure. If the submarine became immobilized and unable to surface, the crew of the submarine could release the buoy from inside of the submarine. This buoy would then surface, carrying with it a length of steel cable. One end of the cable was attached to the buoy while the other end was attached to a cable reel on the submarine. The buoy would then be recovered and the cable used to haul down a rescue chamber to the stricken submarine. Newer class submarines are not equipped with rescue buoys. Instead, they rely entirely on the Deep Submergence Rescue Vehicle (DSRV) for emergencies.

In modern technology, rescue bells and autonomous rescue aid are used to rescue the crews of sunken submarines. Their operating principle is the same and consists in the formation, by connecting coaming-platform bell or coaming-site autonomous rescue apparatus with coaming-platform lying on the ground emergency submarine, sealed air cavities around the emergency escape hatch of the submarine. Due to the cavity created by the possibility of opening the lid of the escape hatch of the submarine and its crew go in life or in the bell chamber autonomous rescue apparatus.

To deliver rescue bells and autonomous rescue vehicles in the area of finding emergency submarine use surface vessels or submarines, which simultaneously serve as a means to operate the rescue bells and autonomous rescue apparatus, and receiving means rescued crew. Practice operations to rescue the submariners showed the efficiency of the use of rescue bells and autonomous rescue vehicles, and their lack of capacity. Cause: An extremely tough conditions of the rescue and the specific environment activities which dictate specific requirements for the structural properties of the rescue equipment, and create a lot of restrictions on their use.

With the growing strength of the Chinese Navy's submarine force and the continuous expansion of its range of activities, the original three submarine support ships have gradually become aging and useless. After 2010, China has built a new generation of Type 926 submarine support ships. Although the tonnage of this type of ship is slightly smaller than that of the previous generation, the full-load displacement is close to 10,000 tons, but the technical performance is not the same. The new all-electric propulsion system is adopted to realize in-situ steering and stepless speed regulation. The angular orientation of the hull can be changed arbitrarily, and the rescue operation can be flexibly carried out according to local conditions. It is also equipped with the world's top level submarine rescue equipment, including imported from the UK. The LR7 deep submersible submarine, domestically produced kilometer deep remote unmanned submersibles, etc.

The 926 submarine support ship has built 3 ships so far, including 864 Ocean Island, 865 Liugong Island, and 867 Long Island. It has participated in various maritime joint military operations including the Pacific Rim military exercise. Submarines, especially nuclear submarines, provide a solid guarantee for ocean-going training.