of US Navy Diving
USS Squalus (SS-192)
World War II
Carl Brashear, Master Chief Boatswain's Mate, USN
Fleet Diving Since World War II
Loss of USS Thresher (SSN-593)
Deep Submergence Systems Project
US Navy Saturation Diving
Open-Sea Deep Diving Records
The US Navy is the forerunner in the development of modem diving and underwater operations. The general requirements of national defense and the specific requirements of underwater reconnaissance, demolition, ordnance disposal, construction, ship maintenance, search, rescue, and salvage operations repeatedly give impetus to training and development.
Early History of US Navy Diving
The early history of diving in the US Navy parallels that of the other navies of the world. Since the middle of the nineteenth century, the Navy has employed divers in salvage and repair of ships, in construction work, and in military operations.
For the most part, early Navy divers were swimmers and skin divers, with techniques and missions unchanged since the days of Alexander the Great. During the Civil War Battle of Mobile Bay, swimmers were sent in ahead of Admiral Farragut's ships to locate and disarm Confederate mines that had been planted to block the entrance to the bay.
In 1898, Navy divers were briefly involved in an international crisis when the second-class armored battleship USS Maine was sunk by a mysterious explosion while anchored in the harbor at Havana, Cuba. Navy divers were sent from Key West to study and report on the wreck. Although a Court of inquiry was convened, the reason for the sinking was not found.
The beginning of the twentieth century saw the attention of all major navies turning towards developing a weapon of immense potential - the military submarine. The highly effective use of the new weapon by the German Navy in World War I heightened this interest, and an emphasis was placed on the submarine that continues today.
The US Navy had operated submarines on a limited basis for several years prior to 1900. As American technology expanded, the US submarine fleet grew rapidly. However, throughout the period of 1912-1939, the development of the Navy's F, H, and S class boats was marred by a series of accidents, collisions, and sinkings. Several of these submarine disasters resulted in a correspondingly rapid growth in the Navy diving capability.
Until 1912, US Navy divers rarely went below 60 fsw (feet of seawater). In that year, Chief Gunner George D. Stillson set up a program to test Haldane's diving tables and methods of stage decompression. A companion goal of the program was to develop improvements in Navy diving equipment. Throughout a three-year period, first diving in tanks ashore and then in open water in Long Island Sound from the USS Walke (Destroyer No.34), the Navy divers went progressively deeper, eventually reaching 274 fsw.
The experience gained in Stillson's program was put to dramatic use six months later when the submarine USS F-4 sank near Honolulu, Hawaii. Twenty-one men lost their lives in the accident and the Navy lost its first boat in 15 years of submarine operations. Navy divers salvaged the submarine and recovered the bodies of the crew. The salvage effort incorporated many new techniques, such as the use of lifting pontoons, but what was most remarkable was that the divers completed a major salvage effort working at the extreme depth of 304 fsw, using air as a breathing mixture. These dives remain the record for the use of standard deep-sea diving dress. Because of the depth and the necessary decompression, each diver could remain on the bottom for only ten minutes. Even for such a limited time, the men found it hard to concentrate on the job at hand. They were unknowingly affected by nitrogen narcosis.
The publication of the first US Navy Diving Manual and the establishment of a Navy Diving School at Newport, Rhode Island were the direct outgrowth of experience gained in the test pro gram and the USS F-4 salvage. When the United Stares entered World War I, the staff and graduates of the school were sent to Europe, where they conducted various salvage operations along the French coast.
The physiological problems encountered in the salvage of the USS F-4 clearly demonstrated the limitations of breathing air during deep dives. Continuing concern that submarine rescue and salvage would be required at great depth focused Navy attention on the need for a new diver breathing medium. In 1924, the Navy joined with the Bureau of Mines in the experimental use of helium-oxygen mixtures. The preliminary work was conducted at the Bureau of Mines Experimental Station in Pittsburgh, Pennsylvania. Experiments on animals, later verified by studies with human subjects, clearly showed that helium-oxygen mixtures offered great advantages over air for deep dives. There were no undesirable mental effects and decompression time was shortened. This early work laid the foundation for development of reliable decompression tables and specialized apparatus, which are the cornerstones of modern deep diving technology.
One year later, in September of 1925, another submarine, the USS S-51 (SS-162), was rammed by a passenger liner and sunk in 132 fsw off Block Island, Massachusetts. Public pressure to raise the submarine and recover the bodies of the crew was intense. Navy diving was put in sharp focus and the Navy realized it had only 20 divers who were qualified to go deeper than 90 fsw. Diver training programs had been cut at the end of World War I, and the school had not been reinstituted.
Salvage of the USS S-51 covered a ten month span of difficult and hazardous diving, and a special diver training course was made part of the operation. The submarine was finally raised and towed to the Brooklyn Navy Yard in New York.
Interest in diving was high once again and the Naval School, Diving and Salvage, was reestablished at the Washington Navy Yard in 1927. At the same time, the Navy brought together its existing diving technology and experimental work by shifting the Experimental Diving Unit (EDU), which had been working with the Bureau of Mines in Pennsylvania to the Navy Yard as well.
In the following years, EDU developed the US Navy Air Decompression Tables, which have become the accepted world standard, and continued developmental work in helium-oxygen breathing mixtures for deeper diving.
The loss of the USS F-4 and USS S-51 provided the impetus for expanding the Navy's diving ability. However, the Navy's inability to rescue men trapped in a disabled submarine was not confronted until another major submarine disaster occurred.
In 1927, the Navy lost the submarine USS S-4 (SS-109) in a Collision with the Coast Guard cutter USS Paulding. The first divers to reach the submarine in 102 fsw, 22 hours after the sinking, exchanged signals with the men trapped inside. The submarine had a hull fitting designed to take an air hose from the surface, but what had looked feasible in theory proved too difficult in reality. With stormy seas causing repeated delays, the divers could not make the hose connection until it was too late. All of the men aboard the USS S-4 had died. Even had the hose connection been made in time, rescuing the crew would have posed a significant problem.
The USS S-4 was salvaged after a major effort, and the fate of the crew spurred several efforts toward preventing a similar disaster. Lieutenant C. B. Momsen, a submarine officer, developed the escape lung which bears his name. It was given its first operational test in 1929 when 26 officers and men successfully surfaced from an intentionally bottomed submarine.
USS Squalus (SS-192)
The Navy pushed for development of a rescue chamber that was essentially a diving bell with special fittings for connection to a submarine deck hatch. The apparatus, called the McCann-Erickson Rescue Chamber, was proven in 1939 when a submarine sank in 243 fsw. The USS Squalus (SS-192) carried a crew of 50 [56 and 3 civilians]. The rescue chamber made four trips and safely brought 33 men to the surface. The rest of the crew, trapped in the flooded after-section of the submarine, had perished in the sinking. The USS Squalus was raised by salvage divers using air and helium-oxygen mixtures. Following renovation, the submarine, renamed USS Sailfish (SS-192), compiled a proud record in World War II.
World War II
Navy divers were plunged into the war with the Japanese raid on Pearl Harbor. The raid began at 0755, 7 December 1941; by 0915 that same morning, the first salvage teams were cutting through the hull of the overturned battleship USS Oklahoma (BB-37) to rescue trapped sailors. Teams of divers were put to work recovering ammunition from the magazines of sunken ships, to be ready in the event of a second attack.
The immense salvage effort that followed at Pearl Harbor was highly successful. There were 101 ships in the harbor at the time of the attack and most sustained damage. The hardest hit were the battleships, being one of the primary targets of the raid. Six battleships were sunk and one was heavily damaged. Four of these were salvaged and returned to the fleet for combat duty; the USS Oklahoma was righted and refloated but sank en route to a shipyard in the United States. Only the USS Arizona (BB-39) and the former battleship USS Utah (AG-16) could not be salvaged.
Battleships were not the only subjects of the salvage effort. Throughout 1942 and part of 1943, Navy divers worked on destroyers, supply ships, and other badly needed vessels, often using makeshift shallow water apparatus inside water and gas-filled compartments. In the course of the Pearl Harbor effort, Navy divers spent 16,000 hours underwater during 4,000 dives. Contract civilian divers contributed another 4,000 diving hours.
While divers in the Pacific were hard at work at Pearl Harbor, a major challenge was presented to the divers on the East Coast. The interned French passenger liner Normandie, rechristened as the USS Lafayette (AP-53), caught fire alongside New York City's Pier 88. Losing stability from the tons of water poured on the fire, the ship capsized at her berth.
To clear the vitally needed pier, the ship had to be salvaged. The Navy took advantage of this unique opportunity for training by using the New York site for a new diving and salvage school. The Naval Training School (Salvage) was established there in September 1942, and was transferred to Bayonne, N J in 1946.
Salvage operations were not, of course, the only missions assigned to Navy divers during the war Many dives were made to inspect sunken enemy ships and to recover materials such as code books or other intelligence items. One Japanese cruiser yielded not only $500,000 in yen, but also provided valuable information concerning plans for the defense of Japan against the anticipated Allied invasion.
The combat diving mission was the same in World War II as it had been in previous wars: to remove obstacles from enemy waters and to gather intelligence. The Navy's Underwater Demolition Teams (UDT) were created when bomb disposal experts and SeaBees (combat engineers) teamed together in 1943 to devise methods for removing obstacles that the Germans were placing off the beaches of France.
The first UDT combat mission, however, was in the Pacific. It was a daylight reconnaissance and demolition project off the beaches of Saipan in June 1944. In March of the next year, preparing for the invasion of Okinawa, one underwater demolition team achieved the exceptional record of removing 1,200 underwater obstacles in two days, under heavy fire, without a single casualty.
Diving apparatus was not extensively used by the UDT during the war. No suitable equipment
was readily available. UDT experimented with a modified Momsen lung and other types of breathing apparatus, but not until 1947 did the Navy's acquisition of Aqua-Lung equipment give impetus to the diving aspect of UDT operations. The trail of bubbles from the open-circuit apparatus limited the type of mission in which it could be employed, but a special SCUBA (self- contained underwater breathing apparatus) platoon of UDT members was formed to test the equipment and determine appropriate uses for
Through the years since, the mission and importance of the UDT has grown. In the Korean Conflict, during the period of strategic withdrawal, the UDT destroyed an entire port complex to keep it from the enemy.
Today Navy combat swimmers are organized into two separate groups, each with specialized training and missions. The Explosive Ordnance Disposal (EOD) team has the mission of han dling, defining, and disposing of munitions and other explosives. The Sea, Air, and Land (SEAL) special warfare teams make up the second group of Navy combat swimmers. SEAL team members are trained to operate in all of these environments. They qualify as parachutists, learn to handle a range of weapons, receive intensive training in hand-to-hand combat, and are expert in SCUBA and other swimming and diving techniques. In Vietnam, SEALS were deployed in special counterinsurgency and guerrilla warfare operations. The SEALs, also participated in the space program by securing flotation collars to returned space capsules and assisting astronauts during the helicopter pickup
Fleet Diving Since World War II.
Navy diving has not been limited to tactical combat operations, wartime salvage, and submarine sinkings. Fleet diving has become increasingly important and diversified since World War II. A major part of the diving mission is the inspection and repair of naval vessels to minimize downtime and the need for day-docking. Other aspects of fleet diving include the recovery of practice and research torpedoes, installation and repair of underwater electronic arrays, underwater construction, and location and recovery of downed aircraft. Ship sinkings and beachings caused by storm damage and human error continue to demand the fleet's salvage and harbor clearance capabilities in peacetime as well as in times of hostilities.
Loss of the USS Thresher (SSN-593)
Just as the loss of the USS F-4, USS S-51, USS S-4 and the sinking of the USS Squalus caused an increased concern in Navy diving in the 1920s and 1930s, a submarine disaster of major proportions had a profound effect on the development of new diving equipment and techniques in the postwar period. This was the loss of the nuclear attack submarine USS Thresher (SSN-593) and all her crew in April, 1963. The submarine sank in 8,400 fsw, a depth beyond the survival limit of the hull and far beyond the capability of any existing rescue apparatus.
An extensive search was initiated to locate the submarine, and if possible, determine the cause of the sinking. The first signs of the USS Thresher were located and photographed a month after the disaster Collection of debris and photographic coverage of the wreck continued for about a year.
Two special study groups were formed as a result of the sinking. The first was a Court of Inquiry, which attributed probable cause to a piping system failure. The second, the Deep Submergence Review Group (DSRG), was formed to assess the Navy's undersea capabilities. Four general areas were examined: search, rescue, recovery of small and large objects, and the Man-In-The-Sea concept. The basic recommendations of the DSRG called for a vast effort to improve the Navy's capabilities in these four areas.
Deep Submergence Systems Project
Direct action on the recommendations of the DSRG came with the formation of the Deep Submergence Systems Project (DSSP) in 1964, and an expanded interest regarding diving and undersea activity throughout the naval service.
Submarine rescue capabilities have been substantially improved with the development of the Deep Submergence Rescue Vehicle (DSRV) which became operational in 1972. This deep diving craft is air-transportable, highly instrumented, and capable of rescue to a depth of 5000 fsw.
Three additional significant areas of achievement for the Deep Submergence Systems Project have been that of Saturation Diving, the development of Deep Diving Systems, and progress in advanced diving equipment design.
US Navy Saturation Diving
The US Navy has developed and proved saturation diving techniques in its Sealab series as well as in ongoing programs of research and development at the Navy Experimental Diving Unit (NEDU), Naval Medical Research institute (NMRI), and the Navy Submarine Medical Research Laboratory (NSMRL) as well as many institutional and commercial hyperbaric facilities. In addition, saturation diving using Deep Diving Systems (DDS) is now a proven capability.
The Navy developed two types of DDS. The DDS MK I supported two 2-man teams of divers through a 14 day mission profile. The DDS MX I system used in trial dives to 1,148 fsw is no longer in service. The DDS MX 2 MOD 1, designed for saturation diving, supports two 4-man teams for an extended mission time. DDS MK 2 is installed as part of the basic equipment of the ASR 21 class of submarine rescue ships
Open-Sea Deep Diving Records
Diving records have been set and broken with increasing regularity in the past 70 years. In 1915 the 300-fsw mark was exceeded when three U.S. Navy divers, F. Crilley, W. E. Loughman, and E. C. Nielson, reached 304 fsw using the MX V dress. In 1972 the MX 2 Mod 0 DDS set the in-water record of' 1,010 fsw which was subsequently broken in 1975 when divers using the MX 1 Deep Dive System descended to 1,148 fsw. A French dive team subsequently broke the open-sea record in 1977 with a depth of 1,643 fsw.
Throughout the evolution of diving, from the earliest breath holding sponge diver to the modem saturation diver, the basic reasons for diving have not changed. The needs of national defense, commerce, and science continue to provide the underlying basis for the development of diving What has changed, and continues to change radically, is diving technology.
Source: Naval Sea Systems Command. U.S. Navy Diving Manual Volume 1 (Air Diving). NAVSEA 0994-LP-001-9110, Revision #2. 15 December 1988. [pages 1-14 through 1-21.].
Note: fsw = feet of seawater