The best known of the U.S. Navy's
submarine salvage operations was conducted on Squalus (SS-192)
in 1932. Like submarines S-51 (SS-162) and S-4 (SS-109),
Squalus was salvaged by lifting with pontoons, but there
are some significant differences that make the Squalus operation
noteworthy. The boat was sunk in 240 feet of water, significantly
deeper than any previous submarine salvage. Better equipment was
available in the form of the McCann Submarine Rescue Chamber,
which was used to rescue crew members, and helium-oxygen diving
equipment that allowed divers to work more effectively in the
greater water depths.
The salvage was planned and conducted in three distinct stages. Unlike previous pontoon salvage operations, control pontoons limited the distance the ship was lifted in any single lift and no water was removed from the hull in deep water.
A new submarine, Squalus (Lieutenant Oliver F. Naquin) submerged with the main engine air induction valve open and flooded the aft compartments on the morning of 23 May 1939 off Portsmouth, New Hampshire. Submarine rescue ship USS Falcon (ASR-2), commanded by Lieutenant Grant A. Sharp, was on site within twenty-four hours. On 24 May 1939, in the first and only use of the McCann Rescue Chamber, thirty-three men were rescued from the forward compartments in four trips. Although there was no reason to believe anyone was alive in the aft part of the ship, a fifth run was made to the aft torpedo room hatch on May 25. This run confirmed the flooding of the entire aft portion of the ship.
The decision to salvage Squalus was made immediately. Rear Admiral Cyrus W. Cole of the Portsmouth Navy Yard was designated commander of the salvage unit and Lieutenant Floyd A. Tusler (Construction Corps), was named salvage officer. A task unit similar in composition to those of the S-51 and S-4 salvages was organized, again with Falcon as the primary work platform. USS Sculpin (SS-191) was the practice submarine.
Because of the Navy's experience in submarine salvage and the availability of sufficient equipment, the salvage plan called for raising the Squalus with pontoons and her internal buoyancy, basically the same method used with S-51 and S-4. The depth of Squalus complicated the salvage problem. When pontoons and the vessel's own buoyancy are used, the exact locations of the centers of gravity and buoyancy cannot be determined; thus one end always rises first. If the rise of the upper end is not constrained, a sharp angle will result and air will spill from open bottom ballast tanks. To prevent a sharp angle, Squalus would be lifted a short distance, towed submerged to shallow water, and lifted again.
To limit the distance the submarine was raised on each lift, the pontoons were arranged at different levels between the surface and the submarine. When the uppermost pontoons reached the surface, their lift would be lost and Squalus would hang in midwater, supported by her internal buoyancy and that of the submerged pontoons. The upper pontoons were known as the control pontoons because they controlled the height of the lift The pontoons were to be arranged athwartships at the bow and stern, with the greatest number supporting the flooded stern. Pontoon placement was handled by methods similar to those used previously, guided down wires that had been passed to chain slings passed under the hull.
The initial depth of Squalus sharply limited the amount of work that could be done by divers. The early days of the operation showed that air diving at this depth was not effective because of inert gas narcosis. The Navy Experimental Diving Unit had done a great deal of research work and some field work with helium-oxygen breathing mixtures Navy Experimental Diving Unit divers, led by Commander Charles B. Momsen and Dr. A. R. Benhke, came to the scene with helium-oxygen diving equipment. As with any new or experimental technique, there were problems with the equipment, but they were solved and almost all diving was done with helium-oxygen equipment. A total of 648 dives were made during the Squalus salvage operation; there were only two cases of decompression sickness.
Even with the helium-oxygen equipment, diving time and the diving work was limited. The decision to lift with pontoons and ballast tank buoyancy only, and not to restore the buoyancy of the aft compartments, was based on limiting the diving work. A tunneling lance was developed for reeving the lifting slings under the hull, eliminating much of the hard diving work of tunneling. The lance, outfitted with a Falcon nozzle and its pipe sections curved to fit the hull, was guided by a diver on the deck of Squalus into the hole its water jet dug. Experience showed that the threaded connections between pipe sections tended to loosen, causing the tunnel to head off in directions unknown. This was solved by toggling the sections together. When the lance was completely around the hull, a wire snake run through the lance and carried the reeving lines around.
All was ready for the first lift. Commander Momsen described what happened:
At the end of fifty days work, connecting hoses, rigging pontoons, attaching bow and stern towing cables, the first lift was attempted. We raised the stern successfully then the bow. The bow came up like a mad tornado, out of control. Pontoons were smashed, hoses cut and I might add hearts were broken. It was the 13th of the month, July. Another 20 days of mopping up was required before we could again rig for another try The second try was successful.
Pontoons were rerigged for the second lift so that more positive
control over the bow was maintained. Squalus was raised
70 feet and towed toward Portsmouth until she grounded. The pontoons
were rerigged for lifting in the shallower water and Squalus
was lifted successfully and towed to the final grounding site
in 92 feet of water.
At this location all chafed hoses were renewed and two pontoons were rigged fore and aft at the stern. When the submarine was raised bow first, she was found to be transversely unstable. She listed heavily to port, dumped air from her ballast tanks, and sank. An attempt to lift the stern first failed because free water ran forward, making the bow too heavy. Two additional pontoons were rigged at the bow, Squalus was lifted and towed to Portsmouth where she was drydocked. Recommissioned as Sailfish, she served in the Pacific throughout World War II.
Squalus was the last submarine salvage operation undertaken by the Navy before World War II. Among the many submarine salvage efforts up to this time, the deep-ocean raisings of F-4, S-51, S-4, and Squalus were truly remarkable operations that demonstrated expertise in seamanship, engineering, and diving. They were all independent events with no real thread connecting them. There was no permanent organization for marine salvage, particularly the salvage of submarines. The organizations put together for each operation were disbanded after the operation. There was no central office to analyze the work and formulate a program to ensure mistakes were not repeated or to advance salvage technology and readiness.
The greatest legacy of this work between the wars was the almost accidental establishment of a tradition of conducting complex salvage operations totally within the Navy and producing excellent technical reports. The latter allowed those who were interested to study the operations and to learn what did work and what did not. The experience gained in submarine salvage also provided background in the organizational and logistical requirements of salvage operations that would prove invaluable in developing World War II salvage forces.