U. S . NAVY'S DEEP SUBMERGENCE

By CAPT James P.WEOH 11, USM

Suhrine Development GroupOhT , CA 92106

ABSTRACT

Since its inception in 1970, Developmenta?d a biomedical research department. The greatest Group OWE113s functioned astine U. S. Navy's sole wealth of experience to date, however, has been with operating arm for underwater search, recovery, and deep suhergence vehicles. Hence, this paper will be rescue. As such, it maintains the largest, most directed toward recent experiences with these systems. diverse collection of DeepSuhergence assets in the world, including , manned and unmanned sub- DEEP SUBMERGENCE RESCUE mersibles, search systems, diving systems, surface ships, and shore facilities. A wealth of operational The Deep Submergence Rescue Vehicle(DSRV) system experiences have been acquired with these assets overhas been designed to providea quick-reaction, world- the past thirteen years in both Atlantic and Pacificwide capability to rescue personnel from a disabled Oceans, leading to the establishrnent of numerous tech-submarine, lying on the ocean atfloor less than niques and equipment developments. This paper will collapse depth. describe specific Subnarine Development Group systems and present results of several recent operations. Each of the Navy's two DSRV's (IUSTIC and AVALON) -Future glans will also be discussed. are designed to mate over the hatch of a disabled submarine and, with a crew of three, carry24 up to INTRODUCTION rescuees per trip back to safety. The outer hull, made of fiberglass reinforced plastic, 50 is feet in length The U. S. Navy's operational command for deep sub- and 8 feet in diameter. Within the lightweight outer mergence systems is Submarine Development GroupONE hull are three interconnected spheres, eachli meters located in San giego, California. The Development in outside diameter and made of HY-140 steel. Each Group was established in 1967 by the Chief of Navalvehicle has an air 75,000 of lbs and is capable Operations as part of the Pacific Submarine . It of submerging to a depth 5,000 of feet. acts as the Naxy'ssole operating arm devoted to the development of deep submergence capabilities for search, Propulsion and maneuvering of the DSRV is achieved location, recovery, and rescue anywhere in the world'sby an electrically-powered stern propeller within a oceans. moveable control shroud and four electrically-powered ducted thrusters (two horizontal and two vertical). Establishment of the Development Group was an out-The DSRV is designed to hover in currents up to one growth of the Deep Submergence Systems Review Group knot and mate with a disabled submarine lying on the established by the Secretary of the Navy1963 in after ocean floor at angles up 45 to degrees. Each vehicle the loss of the Submarine THRESHEX and the demonstratedhas a subinerged enduranceof approximately eight hours. inadequacy of the Navy's deep ocean capabilities as revealed in the searches for the THRESHER in 1963 andSpecial sensors and equipment necessary for 1964 and the H-Bomb off Palomares, Spain1966. in navigation, location and safety include a horizontal Prior to 1967, deep ocean capabilities, where they obstacle avoidance , vertical obstacle avoidance existed at all, rested almost entirely in various sonar, altitude/depth sonar, and short range sonar prototype and "one-of-a-kind" systems. These were com- which outlines any object directly beneath the DSXV monly operated by numerous organizations suchas Navy mating skirt and assists in determining the orientation laboratories, universities, and other institutions of the disabled submarine. Tn addition, each DSRV has generally supported by research and development funds.a doppler sonar, transponder interrogation sonar, Historically, the operating forcesof the Kavy (i.e., television and 35mm still cameras, external flood Fleet) were forced to rely on this mixture of deeplights, and viewports in the forward and middle spheres. ocean assets to respond to contingency operations. MYSTIC In the ten years since its inception, however, the Development Group has centralized the Navy's deep sub- Located atthe Submarine Xescue Unit at North mergence operational experience and assembled the Island Naval Air Station, San Diego, California, each largest array of diverse deep ocean assets ever operatedDSRV and its associated support equipment is capable and maintained under one organization, civilian or of being air transported by three Air Force C-141A military. These assets include deep suhergence aircraft. At-sea support is to be provided either by vehicles, deep submergence rescue vehicles, support a new catamaran ASR-21 Class Submarine Rescue Ship or ships, a research submarine, submarine an 58x437 Class nuclear modified to rescue ships, advanced systems, serve as a Mother Submarine, capable of transporting, schools for training divers and deep subnergence replenishing, launching, and recovering the DSRV while vehicles operators, shore-based maintenance activities,submerged. 379 US. Government work not protected by U.S. copyright. During 1982, MYSTIC conducted two operations of note. The first, taking place during August, was an Alternate Mission Exercise involving equipment and procedures not normally used in the rescue scenario; rather, these operations capitalizedon the usefulness of the DSRVas a search/work platform. The Alternate Xission Package consists of a dual range sidescan sonar, binocular optics, two television monitors, video tape recorder, and16mm picture camera.

During the August time frame, MYSTIC was tasked to search for and identify various objects such as a submarine anchor and deep seat training fixture. The boat successfully operated in a beacon field and exercised all system components in consort with standard onboard functions. These operations pro- vided valuable training which will be applied toward future problems suchas and aircraft recovery.

During the period 6-22 December1982, the MYSTIC Figure 2. MYSTIC being positioned on center well participated in a flyaway exercise to Charleston, cradle of ASR-22ORTOLAN. South Carolina. This exercise was both for training and for the certification of the twin- DOLPHIN hulled ASR, USS ORTOLAN, for launch, recovery, and tracking of the DSRV. USS DOLPHIN (AGSS-555) is the Navy's deep diving submarine. The ship conducts weapons, acoustic, The DSRV system was loaded aboardC-141s two and environmental, marine engineering, and tactical op- one C-5A (figure1) for the flight-from North Island erations in support of the Navy's research and devel- Naval Air Station in San Diego, homeport for the opment communities. Manned by a crew of three off- DSRV'S. icers and twenty-six enlisted men, DOLPHIN is capable of carrying over twelve tons of scientific equipment to sea for periodsas long as three weeks. The ship can deploy from her San Diego, California homeport for out-of-area operations extendingto upseveral months.

In April1982, the ship conducted two weeks of highly productive upper Ocean turbulence experiments to examine near-surface seawater mixing off the coast of Southern California. The ship carried an instru- ment cluster mounted on a nine thousand pound tripod mounted on the forward deck (figure3). Half of these operations were conducted in consort with the R/V ACANIA. The operation was sponsored by the Naval Postgraduate Schoolat Monterey, California and the University of British Columbia in Vancouver, British Columbia, Canada.

Figure 1. DSRV-1 MYSTIC being loaded intoC-5A for flyaway exercise to Charleston, South Carolina.

Once at Charleston, the system was highway transported to the naval base on itsown trailers. The MYSTIC was fit up on the submarine,USS SEAHORSE (SSN-6691, which was to actas a mother submarine(NOSUB) for recovery backup and alsoas a training aid for dock- ing and seating. The MYSTIC was then installedon USS ORTOLAN (figure2) and transported to a dive site south of Grand Bahama Island,Two dives, numbers411 and 412, were conducted in this area with successful launches and recoveries using the center well-lowered cradle of ORTOLAN and several locations and landings on the submergedSEAHORSE. Following this exercise, the system was taken back to base and offloaded for transport to Charleston Air Force Base and the sub- sequent flight home. Not only was this an effective Figure 3. USS DOLPHIN shown with turbulence probe training and certification evaluation, it also gave tripod mounted on bow. additional credibilityto the practice of quickly transporting a complex system several thousand miles away and having it perform reliablyat its destination. During February 1983, the ship conducted a ten day "Deep Tow Sonar Array" operation in support of on-going research sponsored by the Naval Ocean Systems Center, San Diego, California. In this operation, a

380 four thousand foot passive sonar array was towed awayby from SCI than previously thought; the was range a six thousand foot coaxial tow cable. The tow cableable to accurately directSEA CLIFF to ahydrophone length was adjusted by means 12,000of a lb. location, thus verifying range accuracy forsub- a hydraulically-driven winch mounted externally on the merged target; constant depth comparisons SEAwith ship's forward deck. This operation satisfactorily CLIFF depth sensors versus range computed depth denorstrated the PeepTow System and helped to estab- provided a basis for rangedepthn accuracy. This was lish the baseline operation of the steerablebeam, the first opportunity for the range to track a sub- acoustic signal processing system for passive ranging.merged target from the surface to the ocean floor and exercise this area of the computer programs. The In April 1983, DOLPHIN tested a newly designed tracking results obtained whenSEA CLIFF was deeper deployment towing system that offers an inexpensive than the bottom plane of the range were discarded by and practical way to move the ship long distancesrange at personnel until analysis proved them correct. relatively high speeds. The "demonstration tow" The reversal of signs when a target is below the utilized USS POINT LOKq (AGDS-2) as the towing range had not been previously observed and aided in vessel. MLPHIN was towed five hundred nautical "Z" axis verification. miles during a four day period at speeds of up to ten knots. Higher speeds are anticipated for future In February 1983, the SEA CLIFF was used to transits. attempt recovery of a World War I1 Douglas Dauntless (SBD-31, ditched 1942in and resting in During June1983, WLPHIN conducted four days of 3900 feet of water,15 nautical miles off San Diego operations on the 3-Dimensional Tracking Range (figure 5) . The plane had been located on a routine Facility at San Clemente Island near Southern training mission24 months previously and was con- California. The test evaluated thc ebilityto safely sidered to be in good condition and of significant control asuherged submarine in three demensions on historical value. The operation called forSEA CLIFF the range. Submarine tracking certification require- to attach 5/8a inch Kevlar lineto alift strap, ments included exercising automatic tracking alarm originally installed over the cockpit, and transfer features which can alert the submarine to avoid the line to the twin hullASR, USS PIGEON for collisions with other vessels on the range and to recovery. prevent grounding when approaching shallow waters.

SEA CLIFF

SEA CLIFF (figure 4) a small, three-man submer- sible with an operating depth6,500 of feet, is used for underwater research, exploration, and work. Its 7 ft HY-100 hull is cradled within an aluminum framework and the entire assembly is covered with a free-flcadingGRP skin. The vehicle is 26 feet long, 12 feet wide, 13and feet high and weighs approximately 25 tons. It is equipped with two 7-function manipulators which can grasp or cut cable.

Figure 5. WW I1 dive bomber prior to attempted recovery. Line in foreground is attachedto aircraft lift strap and is being payed out from reel on SEA CLIFF.

Unfortunately, the lift structure parted during the lift when the plane 1500was feet off the bottom. The SBD-3 sailed back down, stuck in the mud, nose down, and gradually layed over upside down (figure6). Another dive bySEA CLIFF verified the bomber's position and established that its condition was still good, setting the stage for another attempt at recov- Figure 4. DSV-4 SEA CLIFF as a6,500 ft depth work ery, possibly during the summer1983. of submersible.

During February 1982, SEA CLIFF conducted extensive surveys of the ocean bottom west of San Clemente Island. The survey established the nature of condi- tions for a future tracking range. In addition, the vehicle was usedto recover and survey hydrophones on an existing 3-D range and verify range tracking accuracy. This latter service was not originally planned, but the need was recognized after operations began. The support ship, TRANSQUEST, andSEA CLIFF were tracked by range supplied equipment throughout Figure 6. Dive bomber in nose downattitude immedi- the mission. The following results were obtained: ately following fall backto bottom Currents later the 3D range is able to track targets much furtherpushed it over on its back. TmTLE

The DSV TURTLE has basically identical charac- teristics to SEA CLIFF, except it has been tested and certified to a depth 10,000 of feet.

During October 1982, TURTLE was instrumental in the recovery of a massive OTEC cold water(W), pipe moored in 4,500 feet of water off the island of Hawaii. The CNP was used to test the feasibility of pumping cold water from depth to condense refrigerant gas, vaporized by the relatively warm surface water during the OTEC process. The pipe actually consisted of a bundle of three 4-fOOt diameter polyethylene pipes 2250 feet long which were moored1,000 feet below the surface (figure7) and abandoned. A Figure 8. Surface Towed Search System (STSS) vehicle critical part of the salvage effort was assigned toduring launch. Overboarding A-Frame also functions the TURTLE, specificallyto cut theCWP bottom as submerged tow point. anchor chainso that the pipe bundle could float free for tow backto port. Initial dives on the site In November 1982, the STSS, still undergoing fleet provided an adequate survey. Then the submersible acceptance testing, conducted search operations for a attached pyronol torches to the chain, which were sunken suharine off the coast of San Diego in 4,000 fired remotely after TURTLE cleared the area. The feet of water. A deep ocean transponder(DOT) field torches were unsuccessful in cutting through the was sown and a systematic sonar search conducted, chain, so yet another dive was conductedto mechan- resulting in the locatian and inspection of the ically cut the1 3/8 inch wire ropes that held the SAEALO (figure 9) with TV and photo camera. Excellent pipe to the anchor chain. This was successful and video resolution was obtained at altitudes40 from feet down to5 feet from objectof interest. All in all, some150 hours of tow time were accumulatedin 1982, bringing the STSS closerto serving as an operational fleet system. Polypropylene Line Nylon Hawser

uI Collar Wire Line

Turtle Anchor Bottom cut Weight

prior to recovery. Figure 9. Photo ofUSS SABALO stem taken by STSS during testing.

STSS

The Surface Towed Search System (STSS) consistsof FWR€ PLAVS a sensor vehicle (figure 81, a handling/overboarding unit, a traction winch and cable storage reel, and The natureof deep submergence Dperations will topside control center. The vehicle is designed for continue much as it has. However, the effectivsness 20,000 ft. operationsand carries a high quality of those operations should increase with increased 2-beam, side lookingCTFM sonar, and high capacity reliability of existing assets and the addition/ (5,600 exposures) photo camera. The vehicle is improvement of others. picked up from a deck transfer track, 90rotated degrees, and plunged beneath the water by surface The SEA CLIFF has been dismantled and certain the stern-mounted handling crane. It is then streamed components sentto Mare Island Naval Shipyard, out and towed from boom the tip which also selvesas where a conversionto 20,000 feet operation is being the submerged tow point. Displays and controls are conducted (figure 10). plans call for com- all located within the operations vans including pletion of the conversion in late 1983. winch controls which regulate fish height above the bottom as it fliesat typical speeds of 1-2 knots.

382 SEA CLIFF conversion being machined at Mare Island Naval Shipyard.

The STSS will be upgraded and made more trans- portable by the addition of a Unitized Loading System (ULS) which places most major system compo- nents on a single bed (figure11) which can be highway or air transported and tied to down the deck of a selected ship of opportunity such as a T-ATF. /ADAPTERBOOU AND -- YODUE

HYDRAULIC / EYE

Figure 11. Arrangement of proposed &tized Loading System (ULS) for STSS.

Acquisition of a commercial medium-depth ROV will take place in fiscal year1984 with another scheduled for fiscal year1985. This will expand the role and capability of the Unmanned Vehicle Detachment and provide assets which have beennot readily available up until now for performing long-term remote work functions.

The continual accumulation of experience within the Navy, coupled with a conscious programfor improvement of systems can only result in a more powerful role for the navy deep submergence program in the future.

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