Fourteen days after the USS Thresher (SSN-593) was lost on 10 April 1963, Secretary of the Navy Fred Korth established the Deep Submergence Systems Review Group to examine all naval capabilities in the deep-ocean environment, but especially submarine escape and rescue. The term escape refers to the survivors of a stricken submarine reaching the surface without outside assistance; rescue is the use of external means to remove survivors from a stricken submarine.
The review group recommended the development of small, manned submersibles that could be transported long distances by aircraft and carried to the disaster scene by specially designed submarine rescue ships (ASR) or modified nuclear-propelled submarines. If carried by a submarine, the Deep Submergence Rescue Vehicle (DSRV) could take off from a submerged submarine and travel down to the disable craft, mate with escape hatches to take aboard survivors, and return to the mother submarine.
Although the program was cut back severely, two DSRVs were constructed, completed in 1971-1972 and now based at San Diego. The DSRV consists of three interconnected personnel spheres, each 7-1/2 feet in diameter, constructed of HY140 steel, encased in a fiberglass-reinforced plastic shell. The forward sphere contains the vehicle's controls and is manned by a pilot and copilot; the center and after spheres can accommodate 24 survivors and a third crewman. The survivors can be transferred directly from the stricken submarine to the DSRV and then to a mother submarine without exposure to the open sea. (The two specialized surface ships, the Pigeon [ASR-21] and Ortolan [ASR-22] have been stricken.)
The Mystic (DSRV-1) originally was certified to operate only down to 3,500 feet for technical reasons; subsequently, both she and the Avalon (DSRV-2) were rated at 5,000 feet. One vehicle usually was kept on alert at Naval Air Station North Island for rapid air/submarine deployment; the second was in overhaul, employed in training, or used for other operations.
The vehicles never have had to undertake a real rescue operation.