McCann Submarine Rescue Chamber

The McCann Submarine Rescue Chamber is a device for rescuing submariners from a submarine that is unable to surface.

During the first two decades of the United States Navy Submarine Force, there were several accidents in which Navy submarines sank with the loss of life. The impetus for the invention for the chamber was the loss of S-51 on 25 September 1925, and the loss of S-4 on 17 December 1927. In the case of S-4, all of her officers and men were able to reach non-flooded compartments as the submarine bottomed in 110 ft (34 m) of water. However, the majority soon succumbed. In her forward torpedo room, six men remained alive. Heroic efforts were made to rescue these six, who had exchanged a series of signals with divers by tapping on the hull. In extremely cold water and tangled wreckage, Navy divers worked to rescue them, but a storm forced a stop to this effort on 24 December. Forty men lost their lives.

These experiences led submariner Charles B. "Swede" Momsen to think of technical alternatives for rescuing survivors from sunken submarines, which at that time was still a virtual impossibility. Momsen soon conceived a submarine rescue chamber that could be lowered from the surface to mate with a submarine's escape hatch and proposed the concept through official channels. While in command of the submarine S-1 (SS-105), in 1926, Momsen wrote the Bureau of Construction and Repair (BuC&R) recommending the adoption of a diving bell for the purposes of rescuing entrapped personnel from submarines. But this idea was pigeonholed by the bureaucracy, even during his own subsequent assignment at BuC&R. The loss of S-4 with all hands put the Navy very much "on the spot" because of the loss of lives that might have been saved. The pressure of this incident forced favorable action and Momsen, using the aircraft hangar from S-1, designed and built a prototype submarine rescue chamber.

During the first three months of 1928, divers and other salvage personnel were able to raise S-4 and tow her to the Boston Navy Yard, where she was drydocked and repaired. She returned to active duty in October 1928 and was employed thereafter as a submarine rescue and salvage test ship. Momsen went to sea in the reconditioned S-4 to carry out practical experiments and training with the rescue chambers.

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