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##### DEPARTMENT OF THE NAVY -- NAVAL HISTORICAL CENTER805 KIDDER BREESE SE -- WASHINGTON NAVY YARD WASHINGTON DC 20374-5060

## Diving in the U.S. Navy: A Brief History

Early Historyof US Navy DivingUSS *Squalus*(SS-192)World War IICombat SwimmersCarl Brashear, Master Chief Boatswain'sMate, USNFleet Diving SinceWorld War IILoss of USS *Thresher*(SSN-593)Deep SubmergenceSystems ProjectUS Navy SaturationDivingOpen-Sea DeepDiving RecordsSummaryThe US Navy is the forerunner in thedevelopment of modem diving and underwater operations. The generalrequirements of national defense and the specific requirementsof underwater reconnaissance, demolition, ordnance disposal, construction,ship maintenance, search, rescue, and salvage operations repeatedlygive impetus to training and development. **EarlyHistory of US Navy Diving**The early history of diving in the US Navy parallels that of theother navies of the world. Since the middle of the nineteenthcentury, the Navy has employed divers in salvage and repair ofships, 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 Alexanderthe Great. During the Civil War Battle of Mobile Bay, swimmerswere sent in ahead of Admiral Farragut's ships to locate and disarmConfederate mines that had been planted to block the entranceto the bay.In 1898, Navy divers were briefly involved in an internationalcrisis when the second-class armored battleship USS Maine wassunk by a mysterious explosion while anchored in the harbor atHavana, Cuba. Navy divers were sent from Key West to study andreport 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 allmajor navies turning towards developing a weapon of immense potential- the military submarine. The highly effective use of the newweapon 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 severalyears prior to 1900. As American technology expanded, the US submarinefleet grew rapidly. However, throughout the period of 1912-1939,the development of the Navy's F, H, and S class boats was marredby a series of accidents, collisions, and sinkings. Several ofthese submarine disasters resulted in a correspondingly rapidgrowth 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 programto test Haldane's diving tables and methods of stage decompression.A companion goal of the program was to develop improvements inNavy diving equipment. Throughout a three-year period, first divingin tanks ashore and then in open water in Long Island Sound fromthe USS*Walke*(Destroyer No.34)*,*the Navy diverswent progressively deeper, eventually reaching 274 fsw.The experience gained in Stillson's program was put to dramaticuse six months later when the submarine USS*F-4*sank nearHonolulu, Hawaii. Twenty-one men lost their lives in the accidentand the Navy lost its first boat in 15 years of submarine operations.Navy divers salvaged the submarine and recovered the bodies ofthe crew. The salvage effort incorporated many new techniques,such as the use of lifting pontoons, but what was most remarkablewas**that the divers completed a major salvage effort workingat the extreme depth of 304 fsw, using air as a breathing mixture.These dives remain the record for the use of standard deep-seadiving dress. Because of the depth and the necessary decompression,each diver could remain on the bottom for only ten minutes. Evenfor such a limited time, the men found it hard to concentrateon the job at hand. They were unknowingly affected by nitrogennarcosis.The publication of the first US Navy Diving Manual and the establishmentof a Navy Diving School at Newport, Rhode Island were the directoutgrowth of experience gained in the test pro gram and the USS*F-4*salvage. When the United Stares entered World War I, thestaff and graduates of the school were sent to Europe, where theyconducted 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 airduring deep dives. Continuing concern that submarine rescue andsalvage would be required at great depth focused Navy attentionon the need for a new diver breathing medium. In 1924, the Navyjoined with the Bureau of Mines in the experimental use of helium-oxygenmixtures. The preliminary work was conducted at the Bureau ofMines Experimental Station in Pittsburgh, Pennsylvania. Experimentson animals, later verified by studies with human subjects, clearlyshowed that helium-oxygen mixtures offered great advantages overair for deep dives. There were no undesirable mental effects anddecompression time was shortened. This early work laid the foundationfor development of reliable decompression tables and specializedapparatus, 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 sunkin 132 fsw off Block Island, Massachusetts. Public pressure toraise the submarine and recover the bodies of the crew was intense.Navy diving was put in sharp focus and the Navy realized it hadonly 20 divers who were qualified to go deeper than 90 fsw. Divertraining programs had been cut at the end of World War I, andthe school had not been reinstituted.Salvage of the USS*S-51*covered a ten month span of difficultand hazardous diving, and a special diver training course wasmade part of the operation. The submarine was finally raised andtowed to the Brooklyn Navy Yard in New York.Interest in diving was high once again and the Naval School, Divingand Salvage, was reestablished at the Washington Navy Yard in1927. At the same time, the Navy brought together its existingdiving technology and experimental work by shifting the ExperimentalDiving Unit (EDU), which had been working with the Bureau of Minesin Pennsylvania to the Navy Yard as well.In the following years, EDU developed the US Navy Air DecompressionTables, which have become the accepted world standard, and continueddevelopmental work in helium-oxygen breathing mixtures for deeperdiving.The loss of the USS*F-4*and USS*S-51*provided theimpetus for expanding the Navy's diving ability. However, theNavy's inability to rescue men trapped in a disabled submarinewas 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 hoursafter the sinking, exchanged signals with the men trapped inside.The submarine had a hull fitting designed to take an air hosefrom the surface, but what had looked feasible in theory provedtoo difficult in reality. With stormy seas causing repeated delays,the divers could not make the hose connection until it was toolate. All of the men aboard the USS*S-4*had died. Evenhad the hose connection been made in time, rescuing the crew wouldhave posed a significant problem.The USS*S-4*was salvaged after a major effort, and thefate of the crew spurred several efforts toward preventing a similardisaster. Lieutenant C. B. Momsen, a submarine officer, developedthe escape lung which bears his name. It was given its first operationaltest in 1929 when 26 officers and men successfully surfaced froman intentionally bottomed submarine.**USS *Squalus*(SS-192)**The Navy pushed for development of a rescue chamber that was essentiallya diving bell with special fittings for connection to a submarinedeck 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 tothe surface. The rest of the crew, trapped in the flooded after-sectionof 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 onPearl Harbor. The raid began at 0755, 7 December 1941; by 0915that same morning, the first salvage teams were cutting throughthe hull of the overturned battleship USS*Oklahoma*(BB-37)to rescue trapped sailors. Teams of divers were put to work recoveringammunition from the magazines of sunken ships, to be ready inthe event of a second attack.The immense salvage effort that followed at Pearl Harbor was highlysuccessful. There were 101 ships in the harbor at the time ofthe attack and most sustained damage. The hardest hit were thebattleships, being one of the primary targets of the raid. Sixbattleships were sunk and one was heavily damaged. Four of thesewere salvaged and returned to the fleet for combat duty; the USS*Oklahoma*was righted and refloated but sank en route to ashipyard in the United States. Only the USS *Arizona* (BB-39)and the former battleship USS *Utah* (AG-16) could not besalvaged.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 makeshiftshallow water apparatus inside water and gas-filled compartments.In the course of the Pearl Harbor effort, Navy divers spent 16,000hours underwater during 4,000 dives. Contract civilian diverscontributed 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*, rechristenedas the USS*Lafayette*(AP-53),**caught fire alongsideNew York City's Pier 88. Losing stability from the tons of waterpoured 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 trainingby using the New York site for a new diving and salvage school.The Naval Training School (Salvage) was established there in September1942, and was transferred to Bayonne, N J in 1946.Salvage operations were not, of course, the only missions assignedto Navy divers during the war Many dives were made to inspectsunken enemy ships and to recover materials such as code booksor other intelligence items. One Japanese cruiser yielded notonly $500,000 in yen, but also provided valuable information concerningplans for the defense of Japan against the anticipated Alliedinvasion.**Combat Swimmers**The combat diving mission was the same in World War II as it hadbeen in previous wars: to remove obstacles from enemy waters andto gather intelligence. The Navy's Underwater Demolition Teams(UDT) were created when bomb disposal experts and SeaBees (combatengineers) teamed together in 1943 to devise methods for removingobstacles that the Germans were placing off the beaches of France.The first UDT combat mission, however, was in the Pacific. Itwas a daylight reconnaissance and demolition project off the beachesof Saipan in June 1944. In March of the next year, preparing forthe invasion of Okinawa, one underwater demolition team achievedthe exceptional record of removing 1,200 underwater obstaclesin two days, under heavy fire, without a single casualty.Diving apparatus was not extensively used by the UDT during thewar. No suitable equipmentwas readily available. UDT experimented with a modified Momsenlung and other types of breathing apparatus, but not until 1947did the Navy's acquisition of Aqua-Lung equipment give impetusto the diving aspect of UDT operations. The trail of bubbles fromthe open-circuit apparatus limited the type of mission in whichit could be employed, but a special SCUBA (self- contained underwaterbreathing apparatus) platoon of UDT members was formed to testthe equipment and determine appropriate uses forit.Through the years since, the mission and importance of the UDThas grown. In the Korean Conflict, during the period of strategicwithdrawal, the UDT destroyed an entire port complex to keep itfrom the enemy.Today Navy combat swimmers are organized into two separate groups,each with specialized training and missions. The Explosive OrdnanceDisposal (EOD) team has the mission of han dling, defining, anddisposing of munitions and other explosives. The Sea, Air, andLand (SEAL) special warfare teams make up the second group ofNavy combat swimmers. SEAL team members are trained to operatein all of these environments. They qualify as parachutists, learnto handle a range of weapons, receive intensive training in hand-to-handcombat, and are expert in SCUBA and other swimming and divingtechniques. In Vietnam, SEALS were deployed in special counterinsurgencyand guerrilla warfare operations. The SEALs, also participatedin the space program by securing flotation collars to returnedspace capsules and assisting astronauts during the helicopterpickup**Fleet Diving Since World War II.**Navy diving has not been limitedto tactical combat operations, wartime salvage, and submarinesinkings. Fleet diving has become increasingly important and diversifiedsince World War II. A major part of the diving mission is theinspection and repair of naval vessels to minimize downtime andthe need for day-docking. Other aspects of fleet diving includethe recovery of practice and research torpedoes, installationand repair of underwater electronic arrays, underwater construction,and location and recovery of downed *aircraft.*Ship sinkingsand beachings caused by storm damage and human error continueto demand the fleet's salvage and harbor clearance capabilitiesin 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*andthe sinking of the USS*Squalus*caused an increased concernin Navy diving in the 1920s and 1930s, a submarine disaster ofmajor proportions had a profound effect on the development ofnew diving equipment and techniques in the postwar period. Thiswas 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 thecapability of any existing rescue apparatus.An extensive search was initiated to locate the submarine, andif possible, determine the cause of the sinking. The first signsof the USS*Thresher*were located and photographed a monthafter the disaster Collection of debris and photographic coverageof 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 causeto a piping system failure. The second, the Deep Submergence ReviewGroup (DSRG), was formed to assess the Navy's undersea capabilities.Four general areas were examined: search, rescue, recovery ofsmall and large objects, and the Man-In-The-Sea concept. The basicrecommendations of the DSRG called for a vast effort to improvethe Navy's capabilities in these four areas.**Deep Submergence Systems Project**Direct action on the recommendationsof the DSRG came with the formation of the Deep Submergence SystemsProject (DSSP) in 1964, and an expanded interest regarding divingand undersea activity throughout the naval service.Submarine rescue capabilities have been substantially improvedwith 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 5000fsw.Three additional significant areas of achievement for the DeepSubmergence Systems Project have been that of Saturation Diving,the development of Deep Diving Systems, and progress in advanceddiving equipment design.**US Navy Saturation Diving**The US Navy has developed and proved saturation diving techniquesin its Sealab series as well as in ongoing programs of researchand development at the Navy Experimental Diving Unit (NEDU), NavalMedical Research institute (NMRI), and the Navy Submarine MedicalResearch Laboratory (NSMRL) as well as many institutional andcommercial hyperbaric facilities. In addition, saturation divingusing Deep Diving Systems (DDS) is now a proven capability.The Navy developed two types of DDS. The DDS MK I supported two2-man teams of divers through a 14 day mission profile. The DDSMX 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 two4-man teams for an extended mission time. DDS MK 2 is installedas part of the basic equipment of the ASR 21 class of submarinerescue ships**Open-Sea Deep Diving Records**Diving records have been set and broken with increasing regularityin the past 70 years. In 1915 the 300-fsw mark was exceeded whenthree U.S. Navy divers, F. Crilley, W. E. Loughman, and E. C.Nielson, reached 304 fsw using the MX V dress. In 1972 the MX2 Mod 0 DDS set the in-water record of' 1,010 fsw which was subsequentlybroken in 1975 when divers using the MX 1 Deep Dive System descendedto 1,148 fsw. A French dive team subsequently broke the open-searecord in 1977 with a depth of 1,643 fsw.**Summary**Throughout the evolution ofdiving, from the earliest breath holding sponge diver to the modemsaturation diver, the basic reasons for diving have not changed.The needs of national defense, commerce, and science continueto provide the underlying basis for the development of divingWhat has changed, and continues to change radically, is divingtechnology.Source: Naval Sea Systems Command. *U.S. Navy Diving ManualVolume 1 (Air Diving)*. NAVSEA 0994-LP-001-9110, Revision #2.15 December 1988. [pages 1-14 through 1-21.]. Note: fsw = feet of seawater

*20 November 2000*