Military


ASR 21 Pigeon

ASR 21 Pigeon class vehicles served as surface support ships for deep submergence rescue vehicles (DSRV's) during submarine rescue operations. They conduct these operations using the McCann rescue chamber, and also support deep sea diving operations. These ships can transport, service, lower and raise two Deep Submergence Rescue Vehicles and support diving operations to depths of 850 feet. They can support divers indefinitely, lowering them to the ocean floor in pressurized transfer chambers for open-sea work periods. These vessels also served as operational control ships to conduct deep-sea salvage operations.

For most of the 20th century, when submarines went to sea to conduct sea trials, they were accompanied by a small ship with an important mission. The auxiliary submarine rescue (ASR) ship escorted the submarine, standing by in case of an emergency. The ASR acted as a safety vessel, patrolling the area to warn ships to keep clear of the submarine operating area, and recovered practice torpedoes fired by the submarine. Divers stood ready on board the ASR to perform submarine rescue duties in the event of an accident. Since there was no international flag signal early in the century for this type of operation, the black fish insignia was displayed by all ASRs. Thus ASRs took up the role as "guardians of the submarines," and eventually were formally authorized to display the distinctive black fish insignia beside their hull numbers as a tribute to their mission.

The PIGEON class submarine rescue ships were innovative in both design and capability. Heretofore, submarine rescue meant sending divers down to the stricken craft to attach a steel cable and then hauling down a small rescue capsule known as the McCann chamber. This device can carry about eight survivors to the surface as it is winched up to the rescue ship.

The PIGEON could carry two Deep Submergence Rescue Vehicles, small submersibles that are lowered to the water and then travel down to the stricken submarine and remove up to 24 survivors per trip, carrying them either to the rescue ship or to a submerged submarine. In addition, the PIGEON does carry the McCann chamber and the advanced Deep Diving System Mark II which permits sustained diver activities to depths of 850 feet. Earlier rescue ships could support brief dives to about 300 feet. To provide a large deck area for diving and submersible activities and for increased stability the PIGEON class ships were catamarans, having twin hulls with a broad connecting deck and superstructure. This design also was incorporated in a new oceanographic research ship, the HAYES.

The two Pigeon class ships were the first in the world to be built specifically for the submarine rescue mission and, except for one Military Sealift Command ship, were the first catamaran hull ships built for the Navy since Robert Fulton's Demologos in 1812.

The submarine rescue ship USS PIGEON (ASR-21) entered dry dock for an overhaul at the National Steel and Shipbuilding Company shipyard in April 1992, and was subsequently de-commissioned.

The last U.S. Navy auxiliary submarine rescue ship, the USS Ortolan (ASR 22) was decommissioned in March 1995, thus ending the illustrious era of the auxiliary ships that displayed the distinctive black fish insignia and proudly stood by during most of this century as guardians of the submarines. The mission of submarine rescue is carried on by elements of Commander Submarine Development Group One, including the Deep Submergence Rescue Vehicles (DSRV) Mystic and Avalon and the US Navy divers manning the fly-away submarine rescue chambers at the Deep Submergence Unit, at North Island Naval Air Station, San Diego CA.

No new ASRs are included in the Navy's long range shipbuilding plans.



NEWSLETTER
Join the GlobalSecurity.org mailing list