In 1939, the 'Momsen/McCann Rescue Chamber' made its debut when it was used to successfully rescue thirty-three survivors from 'USS Squalus', At the time of Squalus' accident, Lieutenant Commander Momsen was serving as head of the Experimental Diving Unit at the Washington Navy Yard. The submarine rescue ship USS Falcon (ASR-2), commanded by Lieutenant George A. Sharp, was on site within twenty-four hours. It lowered the Rescue Chamber - a revised version of a diving bell invented by Momsen - and, in four dives over the next 13 hours, recovered all 33 survivors in the first deep submarine rescue ever. McCann was in charge of Chamber operations, with Momsen commanding the divers. Although there was no reason to believe anyone was alive in the aft part of the ship, a fifth dive was made to the aft torpedo room hatch on May 25. This run confirmed the flooding of the entire aft portion of the ship.
'USS Sailfish' (SS-192), was a US Sargo-class submarine, originally named 'Squalus'. As 'Squalus', the submarine sank off the coast of New Hampshire during test dives on 23 May 1939. The sinking drowned 26 crew members, but an ensuing rescue operation, using the 'Momsen Rescue Chamber' for the first time, saved the lives of the remaining 33 aboard. 'USS Squalus' was salvaged in late 1939 and recommissioned as 'USS Sailfish' in May 1940.
As 'USS Sailfish', the vessel conducted numerous patrols in the Pacific War during World War II, earning nine battle stars. She was decommissioned in October 1945 and later scrapped. Her conning tower is on display at Portsmouth Naval Shipyard in Kittery, Maine.