Submarine Escape Technology

With the loss of all hands aboard the S-4 in 1927 came an interest in the possibility of escaping from a sunken submarine. Lieutenant Swede Momsen together with several others designed an oblong, rubber bag that recycled exhaled air. It had a container or soda lime, which removed carbon dioxide from exhaust air and a charge of fresh air from the 225 pound system common to submarines of the time. The "lung" was strapped around the neck and chest and the escaping submariner breathed normally as he made a slow ascent up a line to a buoy on the surface.

Training on the device was wide-spread with hundred foot ascent towers in New London and Pearl Harbor. The short-coming of the device was its shallow depth limit. The Lung was good down to about one hundred feet, but a test depths of submarines at the time was over four hundred feet.

The Momsen Lung was designed as a vehicle for a one-way trip to the surface of the ocean. This singular quality would be replicated in subsequent devices through the next thirty years.

Momsen also pioneered the use of an escape bell which could be mated to the forward torpedo room hatch of a fleet type submarine. The bell was used in the rescue of submariners from the USS Squalus which had gone down from a main induction mishap off the coast of New Hampshire.

During the 1960's the British worked on a series of escape mechanisms. They simultaneously investigated compartment escapes and lock-out systems.

The former roughly equated to an escape from the after torpedo room of an American fleet type boat where a sleeve in the deck hatch was reversed and bolted in place. By partially flooding, then pressurizing the compartment with the 225 pound air system crew members could duck under the lip of the sleeve and get to the surface. The latter was equivalent to the escape trunk in the forward torpedo room of a fleet type boat where the same procedure could be replicated in successive four man escapes.

The British air lock system combined with a method of quick ascent called blow-and-go was successful down to depths of two hundred sixty feet. It should be noted that Germans had made many successful escapes using blow-and-go by riding a bubble or bubble mass to the surface. The British developed a Built-In-Breathing-System hood which was tested down to four hundred fifty feet in laboratory conditions. The rate of ascent was six feet per second with fifty second stops at five intervals.

Attempts to reproduce the laboratory ascents found that the system was good to only two hundred sixty feet, the same as the Blow-and-Go. The BIBS was improved to include an immersion suit which significantly increased the viability of free ascents down to about three hundred feet. They have concluded that ascents from depths below about three hundred fifty feet are too dangerous to attempt by marginally trained crew members.

During the 1960s the United States developed the Stienke Hood (Variously misspelled Steinke and Stenke). The free ascent device consisted of a plastic hood which, when partially charged with treated air, provided four hundred fifty one pounds of buoyancy. As the ascent progressed the crew member breathed the expanding air and excess air was discharged from the hood automatically. Once again the limit of this device was less than many test depths of submarines during the same period.

As test depths increased down to 2000 feet and as operational depths of modern nuclear powered boats out-distanced free ascent methodology the Navy adopted Submersible Emergency Inflation Suits or SEIS. These replicated the British technology and are currently carried aboard modern submarines. However, the gap between operational depths and recoverable depths meant that greater reliance had to be placed in a rescue vehicle that could dive to the stricken submarine, be attached to deck hatches and carry crew members to the surface. Successive dives can be made using this system and the depths at which rescues can be made equal that of the submarine's test depth.

The most significant problem facing the rescue vehicle approach is the tricky job of aligning the vehicle to the hull hatch. Angles-of-lie aggravate the problem and it is here that a new hard suit is of value. The Hardsuit 2000, an Atmospheric Diving System built by a Vancouver, Canada firm allows descents by divers down to 2000 feet. The system can be either umbilicaled to a surface ship or carried as a back pack for free descents. The ADS allows hoses for air, power and fluids to be run to a stricken submarine at hitherto impossible depths. Additionally, the ADS assists in the coupling of ROVS to deck hatches.

Not only does hardware continue to be developed for rescue of crew members at great depths, international submarine rescue seminars have become a bi-annual event with nearly every submarine possessing nation participating.