McCann Rescue Chamber
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.
"Swede" Momsen to think of technical alternatives for rescuing survivors from sunken submarines, which at that time was still a virtual impossibility.
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.
Work with S-4 helped to develop equipment and techniques that bore fruit a decade later, when 33 men were brought up alive from the sunken submarine Squalus.
When the bell was completed in late 1930, it was produced as the McCann Submarine Rescue Chamber (SRC) (Navy designated the first 12 of these as [YRC] 1–12, YRC-4 was lost aboard the USS Pigeon, at Bataan, Philippines, during the first days of WWII.
In 1931, a one-fifth scale model of a diving bell for submarine rescue work was built and tested.
Design called for the bell to withstand the external pressure encountered at a depth of at least 300 ft (91 m) of water, and the test showed the model fulfilled this requirement with a factor of safety of about 3.5.
On the bottom edge of the lower compartment a rubber gasket is embedded into a circular groove, so that when the chamber is brought into contact with a flat surface (the hatch ring) a water tight joint may be effected with the application of pressure.
Attached to the upper compartment is an air supply and an atmospheric exhaust hose, wire wound for strength.
[6] The McCann bell suffers severe limitations in strong currents and when dealing with a pressurized submarine or one lying at extreme angles.
The USN Submarine Rescue Chamber (YRC) is air transportable to a Vessel Of Opportunity (VOO) Mother Ship (MOSHIP) which requires little modification to use the system.
