death. Other concerns include the depletion of oxygen, largely from the fire, the accumulation of carbon dioxide, and the drop in temperature (U.S. Navy 1998).
Most accidents that lead to the disablement and sinking of submarines occur at a depth of less than 300 ft. Down to 600 ft, the crew can escape from the submarine, and down to 2,000 feet, the crew can be rescued (Brown 1999). To escape, a crew member enters the escape trunk and is subjected to pressure equalization (Bond et al. 1960). He then inflates a vest, takes a deep breath, and passes through the open escape hatch. Once outside the hatch, he starts releasing air from his lungs to avoid an air embolism and is carried rapidly to the surface by buoyancy from the vest. In the future, the U.S. Navy will use British submarine escape immersion suits (SEIS) instead of Steinke hoods or inflatable vests. The SEIS suits provide more protection to the crew and contain a one-man raft that can be deployed at the surface. Two crew members can escape together, and the process can be repeated every 15 min. Therefore, it would take approximately 13 hours for a crew of 100 to escape. Numerous risks are associated with escape, including nitrogen narcosis, barotrauma (a type of high-pressure injury to the ear drum, lungs, or bowel), arterial gas embolism, decompression sickness, hypothermia, and drowning (Benton et al. 1999; Parker et al. 2000). The United States and the United Kingdom have conducted submarine escape exercises from depths of 100–600 ft. Several subjects experienced decompression sickness and barotrauma (P.K.Weathersby, Ret., U.S. Navy, personal commun.). A comparison between the health effects associated with escaping from a disabled submarine and those associated with exposure to the eight gases is presented in Table 1–1.
It is difficult to quantify the risks associated with escape from a disabled submarine, however, it is known that attempting such an escape would be extremely dangerous. Because of the substantial risks associated with escape, the Navy’s policy is that, if conditions allow, the crew of a submerged disabled submarine should wait for rescue (U.S. Navy 1998), which can be accomplished by the use of a deep submergence rescue vehicle (DSRV) or a submarine rescue chamber (SRC). The DSRV is a mini submarine that can go to a depth of 2,000 ft. It is attached to the disabled submarine, and 24 crew members are taken at a time from the submarine to a surface ship or to another submarine. The Navy currently has one DSRV, which is kept in San Diego, California. Depending on where in the world a disabled submarine is located, it can take up to 10 d for the DSRV to be transported to a site for rescue. The SRC can be used to a depth of 850 ft. It is lowered to the disabled submarine from a surface ship and can transport 6 crew members at a time to the surface.
As stated above, an event that leads to the disablement and sinking of a submarine is likely to also cause on-board fires. The toxic gases produced as combustion products could include ammonia, carbon monoxide, hydrogen