VOLUME 11.NO.4

EDITOR-IN-CHIEFCDR James E. Roper

ASSISTANT EDITORS-IN-CHIEFCDR Stan Cwiklinski

W. R. Bergman

MANAGING EDITORJoanne L. Wills

DESIGN/PRODUCTION

Kathy Grubb

FACEPLATE is published quarterlyby the Supervisor of Diving to bringthe latest and most informativenews available to the Navy divingand salvage community. Articles arepresented as information only, andshould not be construed as regula-tions, orders, or directives. Discus-sions or illustrations of commer-cial products do not imply endorse-ment by the Supervisor of Divingor the U.S. Navy.

Requests from U.S. GovernmentalAgencies and military activities orpersonnel for distribution copies orfor changes in distribution shouldbe directed to FACEPLATE, Super-visor of Diving (Code OOC-D),Naval Sea Systems Command,Washington, D.C. 20362. Tele-phone (Area Code 202) OX7-7606or AUTOVON 227-7386. All othersuch requests should be directed tothe Superintendent of Documents,U.S. Government Printing Office,Washington, D.C. 20402.

the official magazine for the divers of the United States Navy

4 Soundings(j NSWC: Another Angle on the Mk 12

Ms. Ann RevercombNaval Surface Weapons Center

3 Mk 15 UpdateLCDR Dennis Baber, USNNavy Experimental Diving Unit

10 DEEP DIVE '80

1»5 BUD/S: Step One for a Special Corps18 T-ATF: A New Addition to the MSC Fleet

23 Mk 4 LifepreserverBMC(DV) J.H. Bloechel, USNNavy Experimental Diving Unit

24 HCU-2: Aircraft RecoveryLT Coleman Kavanagh, USNHarbor Clearance Unit TWO

26 HCU-2 "Unsinks" FireboatLT(jg) F.P. Magaraci, USNHarbor Clearance Unit TWO

29 Carpenter Stoppers: The History of TheirUse and DevelopmentCAPT W.F. Searle, USN (Ret.)CDR T.N. Blockwick, USN (Ret.)Mr. N.B. Davis

35 The Old Master

Page 8

Page 10

Page 13Cover: Mk 12 diver surveys, sunken German submarine.Inside cover: Clockwise from top left: fireboat is liftedto surface; Mk 15 diver on horizontal ergometer in theOSF; T-A TF CA TA WBA; BUD/S diver escape training;Mk 12 diver on vertical ergometer. Back cover: Mk 12diver inspects another area of sunken German sub.

FACEPLATE 3

Viewing a model of the ARS-50 Class ship are (left-right): A DM T. M. Hopkins, DeputyCommander for Ship Systems (SEA-05); CAPT Co/in M. Jones, Director of Ocean Engi-neering, Supervisor of Salvage (SEA-OOC); CAPT Peveril Blundell, Executive Director,Ship Design and Integration Directorate (SEA-03); and CAPT Edmund C. Mortimer,Project Manager, Auxiliary/Special Mission Ship Acquisition Project. This gatheringoccurred at the ceremony for the approval and signing of the specifications and the con-tract drawings of the A RS-50. The Design Manager for the A RS-50 is SEA-03; the Acquisi-tion Manager is PMS-383.

CORRECTION

A sentence on page 6 of the Fallissue was inadvertently left out ofthe first NEDU abstract, which mayor may not have caused someambiguity. The Superlite 17B metand exceeded all MIL SPEC require-ments. The actual report goes on tostate "this helmet should provide thediver with a high performance pieceof life support equipment under eventhe most demanding conditions."The Superlite 17B is not authorizedfor Navy use since the Navy has norequirement for this type of equip-ment in addition to its own Mk 1Mod 0 mask."

LCDR MELAMED, ISRAELI NAVY,VISITS NEDU

From August 21 through Septem-ber 16, 1980, LCDR YehudaMelamed, MD, of the Israeli Navywas a guest of the Navy Experimen-tal Diving Unit (NEDU). DoctorMelamed is Commanding Officer ofthe National Israeli Hyperbaric Insti-tute, which is responsible for all ofIsrael's diver equipment testing and

hyperbaric research. His tour atNEDU was spent working closelywith the Medical and Test andEvaluation Departments to get first-hand experience in saturation divingtechniques and unmanned diverequipment testing. He arrived inthe United States in January 1980,visiting various university, commer-cial, and military diving facilities togain state-of-the-art knowledge forthe Israeli Military divingcommunity.

CAVE DIVING

Cave diving appears to have greatappeal to many sport divers, includ-ing some Navy divers. Three Navymen were recently lost in a cavediving casualty, a most regrettableoccurrance. Cave diving is notencouraged in any way. However,if Navy personnel persist in thisactivity in their off duty hours,they should realize that additionaltraining is required. An excellentpamphlet entitled "Cave DivingSafety" is available from theNational Speleological Society, CaveAvenue, Huntsville, Alabama 35810.

CDR Bob Bornho/dt (left), CO of NEDUcongratulates LtCDR Harper.

HARPER MAKES LTCDR,RELIEVES HARWOOD AT NEDU

Stu Harper, Royal Navy, was re-cently promoted to LtCDR at hisnew posting, the Navy ExperimentalDiving Unit, Panama City, Florida.LtCDR Harper relieved LtCDR MikeHarwood as the RN Personnel Ex-change Program Officer in diving onSeptember 17, 1980.

LtCDR Harper has served in theRoyal Navy for 12 years. He hasbeen an MCD (Mine Warfare andClearance Diving Officer) since 1974.Before his arrival at NEDU, he was aPrinciple Warfare Officer aboard theanti-submarine frigate HMS Dido.

LtCDR Harwood returned to theUK after participating in the ad-vancement of several USN EOD-related projects, including the Mk 16Underwater Breathing Apparatus, thePortable Recompression Chamber,and the Mk 4 Divers' Life Vest. Heis presently assigned to the AdmiraltyUnderwater Weapons Establishmentin Portland, England.

4 FACEPLATE

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industrious engineering andresearch went into buildiirg; theSSys-tem. The Navy DepartrneTitSrlqog-"nized; their efforts .thrSiJghiStheissuance of Navy- ; ; Aehleveifteri t :

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main objective was; to icomplete system to fit"74-foot "Mike Boat" (LGM-8)lStrlvout any modifications to

The module is portable^i ble, and can be taken aP3lKil«|;canbe picked' up, placed' "onsfaJ l̂n, :carried aboard ship, |itte)i|;|;;:gMs/abarge, or even lifted via ,hel|l||iterto v/herever distressed:

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NSWC:ANOTHER ANGLE ONTHE MK12 DEVELOPMENT

Packaging the Mk 72 for shipment.

This article is reprinted from "On theSurf ace"-weekly newsletter for theNaval Surface Weapons Center. Theauthor is Ms. Ann Revercomb.

Unplug the old system, plug in thenew—an almost effortless procedurethat in its simplicity belies the exten-sive work required to develop a con-cept into a usable, more efficientproduct.

The new Mk 12 Surface SupportedDiving System is no exception. As 40complete diving outfits were deliv-ered this calendar year to operationalFleet units, new ship constructions,and shore installations, trained mili-tary personnel will be "plugging in"the Mk 12 system to existing on-board equipment. Each delivery cul-minates a 4-year effort to provide theFleet with an alternate to the old Mk5 diving system, adopted more than60 years ago as the standard systemfor use by all Navy divers.

G FACEPLATE

The Naval diving community is al-ready finding the new Mk 12 systeman improvement in many ways. Forthe past year, Mk 12 outfits havebeen used in Navy diving schoolsacross the country for training pur-poses. As anticipated, the Mk 12 isproving to be more comfortable andsafer for divers, while allowing themgreater mobility and flexibility oftasks.

The modernization project wasinitiated through the encouragementof the Navy Experimental DivingUnit (NEDU), Panama City, Florida,the originators of the basic conceptfor the new system. In the late1970's, full sponsorship was shiftedto NAVSEA, with guidance providedby Program Manager Jack Stockard(OOC) and CDR James E. Roper,USN, Supervisor of Diving. Lendingits design and engineering expertiseto the effort was the Naval CoastalSystems Center (NCSC), PanamaCity, Florida.

The role of the Naval SurfaceWeapons Center (NSWC), Dahlgren,Virginia, began during the prelimi-nary design phase in 1976 and hasextended throughout the develop-ment and procurement stages, ac-cording to Bill Furchak (G52),NSWC's former Mk 12 ProjectManager.

"We started out as a technical sup-port agent for NEDU and NCSC," heexplained. "Our responsibilities in-clude providing design review; pre-paring software documentation; per-forming environmental testing; andconducting reliability and maintain-ability analysis. We were subsequent-ly designated as system configurationmanager and as system acquisitionagent for NAVSEA. In this capacity,one of our most significant accom-plishments was to develop the pro-curement package for commercialproduction of the Mk 12."

"In essence, our contributions inthis phase helped to get this equip-ment to the Fleet faster and in amore mannerly and organized fash-ion," he continued. In addition tothese functions, NSWC is involved indesign and redesign of various com-ponents for the Mk 12 system and inproviding technical expertise to Fleetunits using the system.

June 20, 1980, was a red-letterday for personnel from the Engineer-ing Branch (G52), who had workeddiligently on the project. Assemblingand packaging two Mk 12 outfitswere completed on this day, and thefirst shipment to an operational Fleetunit—Harbor Clearance Unit ONE,Pearl Harbor, Hawaii—was under way.Thirty-eight additional outfits will beshipped to 23 locations by the end ofthe year, completing the FY78 pro-curement schedule.

NSWC personnel are also handlingFleet procurement contracts for theFY79 and FY80 buys. With 29 Mk12 outfits purchased for 1979 and 27for 1980, component equipmentarrives regularly at Dahlgren and isstored in the Seaplane Hangar untilFleet deliveries are executed.

As each outfit is delivered, it ishooked up to on-board equipmentpreviously used in support of the oldMk 5 diving system. The efforts ofmany individuals have been, and con-tinue to be, necessary for the Mk 12system to reach this final stage.Five Center engineers have partici-pated on the project over a period of4 years: Don vonAdlerhoch (SEA-05J), Project Manager from 1976 to1978; Jim Mallis (G51); Bill Furchak(OP-051 C), Project Manager from1978 to August 1980; Jim Rasor(G52), the current Project Manager;and Gary Chen (G52).

Able assistance has also been pro-vided by civilian employees and Navypersonnel detailed or loaned to theEngineering Branch of the Survivabil-

ity and Applied Science Division,where the program resides. Includedamong them are: Curtis Sisk (G23),a co-op student; Barbara Hall (M31),detailed from Travel Claims; DorothyBowers (S12), who provided con-tracting support; EMCWayne Walker,USN; and BMC (MDV) "Pete"Petrasek, USN (Ret.).

EMC Walker's services have beenespecially noteworthy, explainedFurchak. "While being regularlyassigned to Yardcraft (G63), ChiefWalker has managed to perform hisduties there as well as lend some ofhis electronics expertise for the de-velopment of test procedures and forthe packaging and assembling of Mk12 electronic equipment."

Essential support has also beenprovided by Petrasek, added Furchak."Before his recent retirement, BMCPetrasek was the diver detailer forthe Navy. He came aboard for 6months in 1979 to coordinate the de-tailing of Diving Supervisors toDahlgren so that they could learn as-sembly procedures for the new

equipment, preventive maintenancemeasures, and corrective actions. Healso coordinated the delivery ofequipment to the diving schools,allowing the Diving Supervisors totrain other divers in the use of theMk 12 system."

Especially appreciated was thework of ENC Clark P. Grover, USN,and ENC Gene Ganske, USN. Thesechiefs, detailed to NSWC for a shortperiod, handled the breakdown ofbulk shipments into individual items,repackaging into individual outfits,and boxing of the outfits for ship-ment.

The Mk 12 system has alreadyproven its worth to the Navy. It hasbeen used in salvage operations inthe Great Lakes; on the salvage ofUSCG BLACKTHORN, sunk inTampa Bay; and on dives to removeexplosive ordnance from the sunkenGerman submarine U-352. Divers in-volved on this last operation statedthat only the Mk 12 made this divepossible, ( s

NSWC management team, l-r: Jim Rasor, Bill Furchak, CAPT Paul Anderson, Dr. L.L. Hill, Dorothy Bowers, Pepe Sanchez, and DavidMa/ye vac.

FACEPLATE ~7

Mk 15 UpdateLCDR Dennis Baber, USN

Navy Experimental Diving Unit

Several important achievementshave been realized in the Special War-'fare Community concerning thedevelopment of the Mk 15 Under-water Breathing Apparatus (UBA).In April 1980, the Chief of NavalMaterial granted Approval for ServiceUse (ASU) for the Mk 15 UBA andthe Full Face Mask after the success-ful completion of their operationalevaluation. In addition, the Mk 15UBA Tables were revised, resulting ina better set of diving tables withwhich a diver can remain at depth fora longer period of time.

The Mk 15, developed and manu-factured by Biomarine Industries, isdesigned to support Special Warfareoperations. To date, 100 units havebeen delivered to the Fleet; and ithas been one of the diving rigs usedat the Basic Underwater Demolition/SEAL training course at the NavalAmphibious School in Coronado,California, for approximately 2 years.

The Mk 15 is a closed-circuit, self-contained, underwater breathingapparatus which circulates the diver'srespiratory gas through a carbon di-oxide absorbent canister. Biologicallyconsumed oxygen is made up andautomatically mixed with the diluentgas (air or nitrogen) through an elec-tronic oxygen sensor array to main-tain a preset 0.70 ATA constantpartial pressure of oxygen regardlessof depth. The N2 — O2 breathingmedium extends Special Warfare mis-sion durations and facilitates in-waterdecompression when required.

An arm-worn Underwater De-compression Computer (UDC) foruse in concert with the Mk 15 UBA

8 FACEPLATE

and Full Face Mask is currentlyunder development. During the sum-mer of 1980, 24 Special Warfarecombat swimmers from UnderwaterDemolition Teams ELEVEN,TWELVE, and TWENTY-ONE, andSEAL Team ONE participated in anexperimental dive series at the NavyExperimental Diving Unit (NEDU).During this series, 204 man diveswere conducted in the NEDU OceanSimulation Facility (OSF) hyperbaricchamber complex. The purpose ofthis study was to revise the initial Mk15 Decompression Tables. A signifi-cant achievement of this programwas the extension of no-decompres-sion limits at 40, 50, 60, 80, 100,and 120 feet of seawater (FSW),respectively. The resulting longerno-decompression limits will provideSpecial Warfare divers with theflexibility needed for both trainingand operating scenarios. Data collect-ed by NEDU medical personnel will

ultimately be incorporated into theUDC software program.

All dive profiles tested multiple,repetitive "working" dives in coldwater with 60- to 80-minute surfaceintervals during which the diversvigorously exercised. Each dive pro-file totaled 5 to 6 hours in duration.The 100-FSW no-decompression diveprofile (water temperature was 60°F)is representative of the multiple,repetitive dives conducted in theOSF wet chamber (below).

During the course of testing, thealgorithm used for computing Mk 15UBA diving tables was revised. Fulldetails of the modified algorithmalong with the complete findings ofthe testing will be the subject of afuture NEDU report. Revised decom-pression times for Mk 15 UBA div-ing will be promulgated in a forth-coming change to the U.S. NavyDiving Manual. ©

DEPTH (FSW)

1000

1000

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17801780178017

ACTIVITY

3.2 Mile Run

Rest

3.2 Mile Run

Dive Profile.

Photos show scenes from Mk 15 UBAstudy in the Ocean Simulation Facility,during which decompression tableswere revised.

FACEPLATE 9

DEEPDIVELCDR J.T. Harrison, USNNavy Experimental Diving Unit

The initial push for DEEP DIVE80 commenced in December 1979,immediately after the completion ofDEEP DIVE 79. Although nofurther dives have been planned thatwould approach the complexityor the historical achievement of the1,800 feet-of-seawater (FSW) DEEPDIVE 79, it was known that a diveof lesser depth would be requiredwithin the next year to verify thelife-supporting characteristics of theMk 11 Underwater Breathing Appa-ratus (UBA) to a depth of 650FSW.

During the ensuingyear, personnelat the Naval Coastal Systems Center(NCSC) developed what appeared tobe a reliable change to the Mk 11UBA breathing loop. After fullunmanned testing in the NCSCHydrospace Lab, the equipment wasconsidered ready for manned testing.

1 September 1980, marked theselection of a seven-man Dive Teamand the beginning of 12 weeks of ex-tensive, detailed, and exhaustivetraining. During the first 5 weeks,the Diver-Subjects never exceeded15 FSW in the Ocean SimulationFacility (OSF) test pool, but theyworked constantly towards equip-ment familiarity and physical condi-tioning in preparation for the dive.All seven members, plus two divesupervisors, had to become inti-mately familiar with the Mk 11

1O FACEPLATE

NEDU DEEP DIVE 198O

DIVE DAY

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Above; Projected and actual Dive profile. Below, top row, left-right: CEl(DV) Anderson, ENC (DV) Daigle, EN2 Carolan. Bottom-l-r: HTC (DV) Baiss (Dive Team Leader), EMl(DV) Patterson, EMl(DV)Moldenhauer,BM1(DY),Bouchey. v :

UBA, the Mk 11 Dry Helmet, theMk 1 Mod S, and the Non-ReturnVolume (NRV) Hot Water Suit.Nominal familiarity with the equip-ment is standard, but NEDU requiresthat Diver-Subjects be thoroughlyprepared for any and all emergenciesthat may occur. The only way toattain such an extensive level oftraining is to log many in-waterhours with the dive rig—repeatingdrill, after exercise, after drill.

Following the 5 weeks of pooltraining, the OSF watchstandersturned to the job at hand. For theensuing 4 weeks, all seven diveparticipants were compressed to30 FSW daily inside the OSF com-plex. The purpose of this daily pres-surization is threefold: First, medicalstudies require at least 28 psi pres-sure to supply sample gas to equip-ment to monitor divers' oral/nasal

and C02 canister gas content.Second, the divers are introduced towhat will become their home for theactual saturation dive, and by havingthem at depth within an enclosedenvironment, they are able to adjustto the reality of total confinement.Third, it afforded realistic training tothe OSF watchstanders.

The OSF is the largest and mostsophisticated hyperbaric complex inthe world, with 3,076 cubic feet ofdry living area and a 55,000-gallonwet chamber. It has six Environ-

mental Conditioning Systems (ECS),five mixed gas lines to each chamber,an elaborate fire suppression system,and an extensive communicationsnetwork. As a result, the start-upoperational procedures are extensive,and the total, undivided attention ofeach watchstander is required.Although all watchstanders havereceived qualification training andhave been duly certified by theNEDU Qualification Board, familiar-ization training is always conductedfor all hands before divers enter the

Diver wearing Mk I Mod S, using a Kinergetics heater.

chambers. This practice ensures thatwatchstanders are aware of anychanges that may have been in-corporated into the system sinceprevious training diving operations.

After the 5 weeks of pool trainingand 4 weeks of training within theOSF, DEEP DIVE 80 was ready toproceed. The chamber was pres-surized to 650 FSW on Dive Day 1(November 4, 1980), and for thenext 9 days, C02 absorbent canisterduration and graded exercise studieswere conducted. Dive Day 10 in-cluded pressurization to 1,000 FSW.For 5 days, the divers conducted drycold thermal studies and wet Mk 1Mod S dives for gas heater studies,using the Kinergetics Model 3375-3heater.

After completion of the work at1,000 FSW, an initial experimentalupward excursion of 170 FSW wasconducted. This resulted in vestibulardecompression sickness to one of theseven Diver-Subjects, who was suc-cessfully treated upon recompressionback to storage depth. The followingmorning, 12 hours after the excur-sion bends, Standard U.S. NavySaturation Decompression was prac-ticed and proceeded without incidentfor the next 11 days to the "sur-face."

During the decompression phase,the studies were continued with theMk 11 UBA, the Mk 11 Dry Helmet,the Tethered Diver CommunicationsSystem (TDCS), and human physio-logical studies to measure mentalattitude and aptitude. The divers"surfaced" on 1 December in goodcondition.

DEEP DIVE 80 was considereda great success because of theamount of reliable test data obtainedfrom the medical studies and theoverall performance of the Diver-Subjects. NEDU's next planned deepsaturation dive to 1,000 FSW isscheduled for the July/August 1981timeframe. Sft

IB FACEPLATE

: small boat exercise. Below: mud-caked HELL WEEK participant.

There is a certain mystique aboutthe U.S. Navy Special Warfare Com-munity and its members. It is one ofadventure, of physical and mentaltoughness, and-at times--of intrigue.These men have been described as"part commando, part bushman, andpart SCUBA diver . . . who knowthe risks and take them . . . . Mento count on."

Fact, fiction, or a little of both?Any attempt to answer this questionmust first include a look at where itall begins: BUD/S, the Basic Under-water Demolition/SEAL trainingcourse taught at the Naval SpecialWarfare Training Department, NavalAmphibious School, Coronado, Cali-fornia.

BUD/S' mission is, simply, totrain motivated U.S. and-on occa-sion-assigned allied personnel asNavy volunteers for duty with theNaval Special Warfare Units: TheUnderwater Demolition Teams(UDT) and the Sea Air Land (SEAL)

Teams. The term "motivated" is keyhere because personal drive anddetermination are essential not onlyto complete the rigorous 23-weekcourse, but just to enter it.

Prospective candidates for BUD/Svolunteer from the following sources:The Naval Academy, Officers Candi-date School, Navy ROTC, BootCamp, "A" Schools, Shore and FleetUnits, and occasionally from alliednations. To apply, one must be maleand 30 years of age or younger.

Those who are medically qualified,meet the administrative requirements,and are capable of passing a physicalscreening test may enter BUD/Sfrom a Recruit Training Center after"A" School or submit a Special DutyRequest (NAVPERS 1306/7) viatheir command to the Chief of NavalPersonnel.

The physical testing for entryincludes: Swimming 300 yards with-in 7-1/2 minutes using the sidestrokeor breaststroke, followed by a 10-minute rest period (standing in anupright position); doing 30 con-tinuous pushups in 2 minutes,followed by a 2-minute rest period;doing 30 continuous situps in 2 min-utes, followed by a 2-minute restperiod; performing six continuouspullups, with palms facing away,followed by a 5-minute rest period;and finally, running 1 mile within7-1/2 minutes wearing full lengthtrousers and either combat bootsor high-top "boondocker" shoes.

FACEPLATE 13

More than a course in basicUDT/SEAL skills, BUD/S can bedescribed as a highly intensive train-ing experience-both physically andmentally. After acceptance into theprogram and before the actualcommencement of BUD/S, studentsundergo a 2-week indoctrinationperiod that emphasizes physicalconditioning and academic review.During this time, the proper under-water recovery swimming stroketechniques and proper exercise andrunning techniques are tau grit-ski I Isthat will be put to increasinglydifficult testing as the course pro-gresses.

Phase I of training is 7 weeks longand concentrates on developing theparticipants' mental and physicalabilities and on testing individualdetermination and the ability to

Top, left: Diver training; right: HMCS Hubbard and QM1 Fuller. Middle: CDR Nelsonwatches exercise session. Bottom: LT Simmons explains Mk 75 UBA during diving phase.

FACEPLATE

work as a team. It also focuses onthe use of basic UDT/SEAL equip-ment as students progress throughlong distance running, calisthenics,obstacle course drills, pool andocean swimming, surf passage, andseamanship in inflatable rubberboats. In addition, the skills ofdrownproofing, flashing light, sema-phore, knot-tying, map and com-pass, and a high speed boat cast andrecovery are taught. Culminatingthis phase is "HELL WEEK," designedto test each student's ability tooperate under adverse conditions forextended periods of time.

Working in small boat crews andwith a total of 8 hours of sleep forthe entire week, the candidates run,swim, and engage in competitiveraces against other boat crews-allperformed in an abundance of sand,surf, and heavy mud. "HELL WEEK"is such that, when a student com-pletes this period, he is consideredto be well on the way to graduationfrom BUD/S. According to CDR TomNelson, the Director of the SpecialWarfare Training Department: "'HELLWEEK' is termed such because it iscarefully designed as the ultimatetest of a student's mental and phy-sical capabilities while in the first

Photos above show various scenes of BUD/S physical, diving, marksmanship, and reconnaissance training.

FACEPLATE 15

phase of BUD/S training. Contrary topopular opinion and the mythsgenerated by preceding classes, sep-arating the physically weak from thephysically strong is not one of thegoals of HELL WEEK. Rather,it is designed to instill in the BUD/Sstudent the qualities and personalcharacteristics which are so importantin becoming a professional in theSpecial Warfare Community: deter-mination, courage, level-headedness,self-sacrifice, and a strong teamspirit."

Phase II, which lasts 8 weeks, isthe diving phase. Diver training forBUD/S students differs from basicNavy diving training because of themore specialized mission of theSpecial Warfare Community. DivingOfficer LT Larry Simmons notesthat "Naval Special Warfare diving isunique in that it stresses the clandes-tine infiltration of enemy shoresrather than deep or working dives."One could say that the emphasis ismore on horizontal transit on orbelow the surface, rather than onvertical movement underwater.

Phase II qualifies students in thecare and use of open-circuit SCUBA(using compressed air), the closed-circuit Emerson rig (using 100percent oxygen), and the closed-circuit Mk 15 Underwater BreathingApparatus (UBA)-a variable, mixed

Small boat exercise. Below: Enjoying lunch in the mud.

gas apparatus that is relatively newto the Fleet. Free ascent, divingemergency procedures, and sub-marine escape trunk training are alsoconducted during this period. Thediving phase demands academic abil-ity as well as physical stamina.Comprehensive classroom studies ofdiving physics and medicine aregiven before pool indoctrination andopen water swims.

Phase III is 10 weeks long andconcentrates on land warfare, includ-ing small unit tactics, weapons, alltypes and uses of explosives, hydro-

graphic reconnaissance, communica-tions, and navigation through varioustypes of terrain under day and nightconditions. Practical application ofthis training is conducted during a20-day period at the BUD/S trainingfacility at San Clemente Island offthe southern coast of California.Here they practice heavy demoli-tions, make live demolition raids,and complete a series of long swims-the final one being a distance of 4 to6 miles.

A student must make a firm com-mitment to the training program andmust dedicate himself mentally andphysically to achieving the ultimategoal of graduation. It is not easy.Only 50 percent of those candidatesthat report for BUD/S indoctrinationeventually graduate from the course.For those who do, there are 3 addi-tional weeks of parachute trainingat Fort Benning, Georgia, beforereporting to either a SEAL or UDTunit Also, an extra 2 weeks ofinstruction are provided' for theSpecial Operations Technician stu-dents following their graduation.During this time, the hospital corps-men are given additional training indiving physics and underwater phy-siology to give them a more thoroughunderstanding of the effects ofpressure on the human body, acci-

16 FACEPLATE

dent prevention, gas analysis, mixedgas diving, treatment of divingdiseases, and use of the recompres-sion chamber.

After serving a 6-month proba-tionary period with a UDT or aSEAL unit, graduates are at lastentitled to wear the Naval SpecialWarfare insignia. They have proventhat they are qualified to be mem-bers of this elite corps.They haveproven that they are worthy ofmaintaining that "special" mystique.(]

Top, left: explosives handling; right: high speed bout cast and recovery. Middle, left: rape/l-ing; right: student "rings out" after graduation ceremony. Above: diving training tower atBUD/s.

History:Special Warfare teams trained their

own replacements until the early 1950's,when BUD/S was started on both coaststo meet the requirements of the KoreanWar. In May 1971, the east coast trainingfacility closed and all instruction wasconsolidated at the Naval AmphibiousSchool in Coronado, where ithas remained.The School also provides training invarious other areas in addition to BUD/S:Swimmer Delivery Vehicles, SpecialOperations Technician, Diving Supervisor,Indoctrination to the Service Academy,and escape training for submariners, Navydivers, and other qualified personnel whowish to learn escape training, lock in/lockout, buoyant ascent, and other relatedsubjects.

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T-ATF:A NewAdditionto theMSC Fleet

The Ocean Fleet Tugs (T-ATF-166Class) are new ships that combinesome of the capabilities of the U.S.Navy's tugs, ATF's, and the com-mercial offshore tug/supply boats.They are an intended replacement ofthe aging World War II ATF's, lastconstructed in 1946.

As a unit of the Mobile LogisticsSupport Force, the mission of thesenew ships is to take in tow ships ofthe Fleet that are battle damaged ornon-operational. To accomplish this,the T-ATF is capable of performingtowing tasks using permanently in-stalled equipment that is operatedby the civilian Military SealiftCommand (MSC) crew.

Also, the ship can accomplishvery limited diving and salvage opera-tions with portable equipment oper-ated by U.S. Navy salvage and divingpersonnel, and can engage in oilspill cleanup tasks with portableequipment operated by NAVSEAOOC pollution contractor personnel.Portable equipment is broughtaboard from shoreside equipmentpools. The salvage, diving, andpollution abatement personnel arealso not on board, but embark whenneeded as transients to provide theexpertise necessary for a particularmission.

The T-ATF propulsion system ismade up of twin 20-cylinder dieselsdriving through reduction gears toseparate shafts with controllablepitch propellers in nozzles. The tow-

n

18 FACEPLATE

\ng equipment consists of a towingand a traction winch, which, whencombined with the large open aftermain deck, provides a platform forperforming towing and limited sal-vage and diving portable payloadmissions.

T-ATF operations can be classi-fied in two general areas: full-timeship functions-for which the MSCcrew uses the permanently installedequipment—and portable functions-which are performed with equipmentloaded on board for specific opera-tions, under the control of Navytransient salvors.

The T-ATF's are equipped torespond quickly to a call from a shipin danger without having to returnto port first. Full-time functionsinclude the following capabilities:

• Wire rope towing: The ship iscapable of taking various typesand sizes of vessels for longdistance tows. Two- and one-quarter-inch wire rope, 2,500feet in length, is spooled ona single drum winch that isdriven by its own diesel engine.

• Synthetic hawser towing: Thetowing capability of the T-ATFis increased through the use ofa traction machine and the useof synthetic hawsers of up to a15-inch circumference.

The combination of the conven-tional wire tow with the tractionmachine for synthetic hawsers offerssimplicity and increases the relia-bility of the system.

• Quick reaction system: Thissystem provides the T-ATFwith an ability to preventbeaching or broaching of an-other vessel or to conduct de-beaching operations. In theevent the T-ATF receives a callto assist a ship that has beenbeached or is in danger ofbeing beached, the first at-tempt would be to pass a tow-line and pull with the ship'sengines and/or towing winch ortraction machine. The bowthruster may also be used,depending on the extent of the

FACEPLATE 19

grounding, to swing the T-ATFthrough arcs from port to star-board. Should this method fail,or if the T-ATF cannot main-tain headway because of windand/or current conditions, theMoorfast anchor would bedeployed.

The Moorfast anchor can be usedto hold the ship's head while pullingwith the main engines and towline.

• Mooring: The T-ATF is cap-able of taking up position andadjusting within a multi-pointmoor of up to four legs thathas been laid by another ship.

• Firefighting and dewatering:Firefighting is accomplished us-ing the installed fire monitorsin the superstructure andtwo diesel driven 1,500-GPMpumps with or without usingthe installed protein foam sys-tem. Located on the main deckaft are two manifolds, each ofwhich can handle up to fivestandard 2'/2-inch hoses. Con-necting the hoses to theinstalled manifolds and to thetug's portable eductors placedon a distressed vessel enablesthe crew to dewater a floodedship.

With portable equipment and addi-tional Navy and/or contractor per-sonnel, the T-ATF is capable of per-forming the following tasks:

• Salvage: When the T-ATF isassigned to a salvage mission,portable salvage equipmentsuch as a work boat, salvagecompressors, salvage weldingmachines, hydraulic pullers,etc. are loaded on board usingthe ship's crane. U.S. Navysalvage teams specially trainedto operate this equipmentboard the T-ATF and work inconcert with the MSC crew tocarry out the task.

• Diving: When assigned a divingmission, portable diving gear isloaded on board. This equip-ment could include diving com-pressors, HP air banks, divingstage or diving bell, two-lock

Fan tail set up for diving ops.

recompression chambers, etc,which are operated by U.S.Navy diving teams. The T-ATFcan support SCUBA diving,surface tended Mk 12 hard hatdiving, and surface tendeddiving using the USN Mk 1diving mask. In all divingmissions, the function of theMSC crew is to secure theT-ATF in a moor after arrivingat the diving site and to pro-vide living accommodations.Once at the site, Navy diverswill conduct the actual opera-tions.

• Oil spill control system: TheT-ATF can support a Navy off-shore oil spill control responseteam in spilled oil contain-ment/deflection recovery andin vessel oil offloading opera-tions. Specialized spill controlequipment from one of thefour strategically located Emer-gency Ship Salvage Material(ESSM) Bases can be deck-loaded on the fantail of theT-ATF. A NAVSEA OOC con-tractor response team boardsthe ship at a convenient portof embarcation.

The offshore spill control equip-ment includes oil containment/de-

Moorfast anchor is stowed in the hull.Page 21: Fantail loaded with oil spillequipment during exercise in SanFrancisco Bay.

SO FACEPLATE

flection boom and boom mooringsystems; oil skimmer vessels andrecovered oil storage barges or por-table bladders; hydraulic submersibleoil offload pumping systems; andworkboats, lightering fenders, shopvans, and other ancillary supportsystems to ensure self-supportingoperations. The MSC crew is re-sponsible for getting the spill con-trol equipment to the operationsarea after it has been loaded aboardand for providing general platformsupport.

The T-ATF 166 Class ship isarranged in five main levels or decks:the bridge deck, the upper deck, thefoc'sle deck, the main deck, and thehold. In addition, there is the topwheelhouse deck, the firefightingplatform, and the shelter deck atthe bow.

Equipment that is permanentlyinstalled is used during the conductof various diving and salvage tasks,and is not associated with any oneparticular job. The three majoritems in this category are the crane,Monark workboat, and bow thruster.

The crane has a telescoping boomthat can extend 64 feet and is cap-able of handling a 10-ton load at35 feet during a 7-degree roll of theship from upright to extreme portor starboard in a duration of 12seconds. It is used for shipping theportable bulwarks on the port andstarboard sides and also in handlingall portable diving and salvage gear.The ability to rotate the boom with-out vangs and the self-stowing cap-ability of the retracting boomrepresent an improvement over theking post and boom arrangement ofthe older ATF's. The crane requiresonly one man to operate it.

The Fleet Tug's workboat, a 24-foot all-aluminum V-hulled craft, isused during mooring operations tocarry the hawsers to the buoys forhookup and when slipping the moorto disconnect from the buoys (wea-ther conditions permitting). Theboat may also be used during salvageoperations for limited transfer ofmen and equipment.

The bow thruster is used duringmooring operations to adjust theship's position within the moor.Also, if conditions permit, it isused to work a distressed vessel outof its grounded position by swingingthe T-ATF through a wide arc whilegoing ahead on the main engines.

Another important item aboardthe tugs are the capstans. Actually,there are five on this ship—one per-manent on the main deck, two por-table capstans, and two anchorwindlasses/capstans on the foc'sledeck. The permanent one is a 2-speedelectric motor-operated vertical cap-stan. It is capable of handling 11-inchnylon and is rated for 30,000 poundspull at20feet per minute and 15,000pounds pull at 40 feet per minute.Two 2-speed electric motor-operatedportable capstans are sized for 6-inchnylon and are rated for 5,000 poundspull at 20 feet per minute. The twoanchor windlasses are rated at 27,000pounds pull at 20 feet per minute.

The T-ATF 166 Class ships aremanned by a crew of 16 MSC andfour Navy communications person-nel. The MSC crew are civilianemployees who are licensed orcertificated in accordance with theCode of Federal Regulations govern-ing merchant marine personnel. TheNavy communicators are Navy per-sonnel assigned to the T-ATF as aduty station.

The T-ATF ships POWHATANand MOHAWK are assigned to theNaval Surface Forces Atlantic. CAT-AWBA, NARRAGANSETT, andNAVAJO are assigned to the NavalSurface Forces Pacific. Two T-ATF's-SIOUX and APACHE-arescheduled for delivery to the Fleetin early and mid summer.

All delivered vessels have com-pleted diving and salvage trainingexercises in conjunction with HarborClearance Units ONE and TWO andwith Service Squadrons FIVE andEIGHT, respectively. During 1980,NARRAGANSETT and CATAWBAcompleted oil pollution abatementexercises in the San Francisco Bayarea and offshore in the PacificOcean, while POWHATAN con-ducted the same tests offshore in theAtlantic Ocean.

POWHATAN has been involved inseveral missions within the last year.In April 1980, using the Shell"SOCK" skimmer, it provided out-standing support for the only inten-tional oil spill tests in U.S. coastalwaters (off the New Jersey coast).This 10-day operation included thedispersal and retrieval of 50 cubicmeters of crude oil. POWHATAN'sversatility and the cooperation of itsMSC crew contributed to the success-ful execution of this task. In June1980, POWHATAN-with the SUP-SALV DEEP DRONE and Special

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Warfare Group (SPECWARGRU)TWO divers aboard--was involved inthe recovery of a helicopter off St.Croix. The deck space available onPOWHATAN's fantail proved to bemore than adequate for the DEEPDRONE system, SCUBA dive team,and the recovered helicopter wreck-age.

Because the water depth wasapproximately 3,000 feet, the shipwas required to keep station dynam-ically while DEEP DRONE, an un-manned tethered vehicle, was operat-ing. To avoid cable entanglement,POWHATAN's Master used the portscrew and the bow thruster to main-tain station within 600 feet (hori-zontally) of the vehicle. For therecovery of heavy objects, a 6,000-foot 41/2-inch nylon hawser was usedin conjunction with POWHATAN'straction machine. Lighter objectswere brought to the surface by DEEPDRONE, where SPECWAR SCUBAdivers transferred the objects toPOWHATAN's 10-ton crane and thelift aboard was completed.

Most recently, POWHATAN com-pleted towing operations involvingNavy pontoons in the Azores. After

T-A TF workboat assists at back end of fantail.

the successful conclusion of the sal-vage portion of this task, conductedby Harbor Clearance Unit TWO, thepontoons were barge loaded and onewas towed to Norfolk, Virginia, byPOWHATAN. In January 1981,NARRAGANSETT illustrated theversatility of the T-ATF ships whenit completed a task as a cargo vessel.

Though T-ATF's were not originallydesigned with such a capability inmind, NARRAGANSETT transport-ed a rather large amount of cargo (onthe main deck) to Diego Garcia fromSubic Bay.

It appears that the T-ATF 166class ships will be a useful additionto the MSC Fleet. (£>

POWHATAN underway.

CO2CARTRIDGE INFLATIONMECHANISM

OVER-PRESSURE RELIEFVALVE

OUTER FABRIC ENVELOPE

INNER BLADDER

ORAL INFLATION HOSE

CO2 CARTRIDGEINFLATIONMECHANISM

Mk 4 Diver's Life PreserverBMC(DV) J. H. BloechelNavy Experimental Diving Unit

The Mk 4 Diver's Life Preserver(DLP) was designed to provide safeand dependable support for all openand closed circuit SCUBA (the Mk's15 and 16 Underwater BreathingApparatus) diving operations todepths of 200 feet of seawater(FSW).

The Mk 4 DLP is a yoke-type gar-ment that utilizes a single urethaneinner bladder, which is enclosed inand protected by a lusterless blacknylon fabric envelope. A non-metallic zipper in the neck openingprovides access to the inner bladderfor inspection and/or repair. Theharness assembly is of black nylonconstruction with plastic quick-releases on both the spine/crotch andwaist straps for ease in donning andremoval. The oral inflation hose withits mouthpiece and manual oral in-flation valve is held in place by aVelcro tab and is readily available tothe diver for oral inflation purposes.The over-pressure relief valve is

mounted low on the front of theDLP and is protected by the utilitypocket. The over-pressure relief valveis designed to lift at 2—2.5 psig overbottom pressure. The two CO2 car-tridge inflation mechanisms are thesame type employed by the Mk 3DLP and require the same care andmaintenance as before to ensureproper operation. It should be notedhere that the problems with the Mk 3inflation mechanisms have long beenrecognized and that a new non-mag-netic device is being developed. Allmaterials used in the construction ofthe Mk 4 DLP are non-magnetic.When the DLP is used by ExplosiveOrdnance Disposal personnel, itshould be used with Type II MIL-C-16385 C02 special non-magneticcartridges.

The Mk 4 DLP, utilizing four 31-gram CO2 cartridges, will provideapproximately 20 pounds of positivebuoyancy at 200 FSW. This will pro-vide sufficient lifting buoyancy tostart a diver with a completelyflooded Mk 15 or Mk 16UBAto the

surface from a depth. On the surface,a fully inflated Mk 4 will provide 42pounds of buoyancy and will supportan unconscious swimmer in a face-upposition in sea conditions up to seastate 3.

Since the Mk 4 DLP is a safety de-vice, properly performed scheduledmaintenance is essential to maintaina high reliability level and user confi-dence. Before any dive, all equip-ment will be carefully inspected. Thepre-dive inspection of any life pre-server must be the personal concernof each diver.

The life preserver support pack-age-with its Mk 4 DLP, Operationand Maintenance (O&M) Manual, re-pair, test and spare parts—is nowbeing issued to the Fleet. With anynew equipment package, mistakes arelikely to turn up, particularly in theO&M instructions. Fleet divers canhelp make this a viable system byreporting mistakes found in theseinstructions to the Navy Experi-mental Diving Unit in care of BMC(DV) Bloechel. ®

FACEPLATE S3

L T Co/eman Kavanagh, USNHarbor Clearance Unit TWO

"Thou arewedded to calamity...."— Shakespeare

Could the great playwright havebeen describing Harbor ClearanceUnit TWO in 1598? Most unlikely.However, HCU-2, as the AtlanticFleet's quick response diving and sal-vage team, often plays a vital rolefollowing an unfortunate turn offate.

On Friday afternoon, November14, 1980, a pilot attached to AirTest and Evaluation Squadron FOUR(VX-4) at the Naval Air Test CenterPatuxent, Maryland, was flying overthe upper reaches of the ChesapeakeBay near Bloodworth Island. His air-craft was the Navy's FA-18 Hornet,the first in a new generation of singleseat multi-mission tactical aircraft.Sleek and fearsome, the Hornetcould handsomely complement themovie set of the next Hollywoodouter space shootout.

Shortly after 1500, the pilotradioed to report that he was havingserious problems with the aircraftand would have to eject The pilotwas "plucked" unhurt from the chill-ing waters of the Chesapeake Bay bya SAR helicopter. The crippled Hor-net spun down into the bay, finallycoming to rest in 20 feet of murkybrackwater approximately 3/4 of amile west of low, marshy HollandIsland.

A search of the area was conduct-ed by a SAR boat and divers fromthe Naval Surface Weapons Center,Solomons, Maryland. The divers ar-rived after dark and searched withoutsuccess—only minor floating debriswas recovered that night.

On Saturday morning, a helicop-ter joined the SAR boat in searchingfor the downed FA-18. Locating andbuoying the wreckage site in the lateafternoon, the NSWC FAC diversawaited the ex-Coast Guard BuoyTender BRIAR. Using BRIAR as aplatform, a survey dive was conduct-ed at dusk and additional markerbuoys were attached.

Commander, Service SquadronEIGHT tasked HCU-2 with providinga salvage master and support divers.LT Donald R. Coins and three diversarrived that night at the SolomonsFacility and were briefed on theoverall situation.

On Sunday afternoon, November16, BRIAR returned to the wrecksite, established a two-point moor,and conducted one survey dive be-fore darkness. Despite visibility of 1to 3 feet and a water temperature of45°F, this dive recovered the air-craft recorder and one instrumentbox. The aircraft was discovered tobe in three major pieces: engine andtail section, port wing and fuselage,and starboard wing. Numerous small-er components littered the hardsandy bottom.

An underwater video-recorder wasbrought up from Norfolk, Virginia.Using the Mk 1 Band Mask, hotwater suits, and compressors from aFly-Away Dive System (FADS), thedivers conducted a complete video-tape recording of the major wreckageand the immediate area for theInvestigation Board. While awaitingthe arrival of the floating craneYD-233, in tow from Norfolk, thethree remaining instrument boxeswere recovered.

It was fortunate that salvage oper-ations had gone so smoothly. Shortly

after the arrival of the YD-233, highwinds and heavy seas precluded fur-ther operations. The floating cranewas positioned in a three-point moorwith BRIAR alongside.

When the wind and seas had sub-sided somewhat, the YD-233 was re-moored into a more favorable posi-tion that provided a lee for divingoperations. By Wednesday afternoon,the divers had rigged the major piecesof the aircraft for lift. The nose sec-tion broke off just aft of the cockpitduring the lift and was recoveredseparately.

It was estimated at the time thatapproximately 27,000 pounds ofwreckage were recovered by usingthe crane. The NSWC FAC and HCUdiving team utilized SCUBA and ajack stay to comb the cloudy bottomfor additional debris. The methodicaluse of the jack stay permitted recov-ery of all remnants within a 100-foot radius of the impact area.Attempts were made to locate theejection seat, an item greatly desiredby the Accident Investigation Board;but the high probability area wasswept with a drag line towed be-tween two Boston Whalers withoutsuccess. All recovered wreckage wasdelivered to NSWC FAC Solomons,where skilled investigators began topiece the puzzle together.

The harmonious and efficient sal-vage effort by Harbor Clearance UnitTWO and Naval Surface WeaponsFacility Solomons personnel onceagain exemplifies the comradery andsingleness of purpose that existthroughout the Navy Diving andSalvage Community. (Jfc)

S4 FACEPLATE

Above: FA-18, Left and below: FA-18wreckage retrieved from Chesapeake Bay.

FACEPLATE 25

HCU-2"Unsinks"a FireboatLT(jg) F. P. Magaraci, USNHarbor Clearance Unit TWO

During the predawn hours onOctober 10, 1980, a civilian securityguard at the Naval Weapons Station,Yorktown, Virginia, was making hisnormal rounds and discovered thatthe 60-foot (49-ton) station fireboathad sunk.

• Upon notifying all concerned,immediate action was initiated bythe Public Works Department tocontain any fuel that might leak.The Ordnance Department wasdirected to conduct an initial assess-ment dive using Weapons Station(EOD) diving personnel.

Results of the initial dive deter-mined that the boat was resting up-

right in 28 feet of water, with thestern in the mud approximately4—6 feet. The starboard side wastight against the pilings of the fingerpier where she had been moored.Commanding Officer, Harbor Clear-ance Unit (HCU) TWO was taskedby COMSERVRON EIGHT to con-duct the salvage of the craft.

A five-man diving team arrivedon scene by early afternoon onOctober 10 to survey the sunkencraft. Their first priority was todetermine the extent of the problemand the assets necessary for recovery.Based on the results of the initialsurvey, a tentative salvage plan wasdiscussed that would involve thecombined lift of two 50-ton mobilecranes and dewatering of the craft'sinternal compartments once it wason the surface. On October 11, HCU-2 personnel, assisted by ReserveHarbor Clearance Unit (RHCU) TWOpersonnel from DET 506, Norfolk,Virginia, and DET 813, Chicago,Illinois (the latter being on duty forweekend WET training), were mobil-ized to conduct the salvage attempt.By noon that day, all diving and sal-vage equipment was in position forthe initial salvage effort. Divingassets included SCUBA and the Mk 1Bank Mask with the new RHCU sur-face supplied diving system. Theportable diving system provided byRHCU-2 DET 506 proved ideal forthe job. Other salvage assets includedtwo mobile 50-ton cranes, two setsof 50-ton spreader bars, four nylonlift straps, three 2-1/2-inch home-lite stripping pumps, eight 10-inchDC plugs and four 3/4-inch wiremessenger straps.

After finalizing the salvage plan,it was decided that a wire messengercould be swept under the stern aftof the rudder after scouring out mudapproximately 4 feet deep. The sameprocedure was to be repeated for-ward, but would not be as difficultsince the bow was not imbedded inthe mud. Once the messenger wireswere passed under the boat thenylon straps would be connectedat one end and rendered around the

SB FACEPLATE

hull, utilizing the mobile cranes.When this was accomplished, thespreader bars and legs would beattached to the two eyes of thenylon straps. A light strain wouldbe put on the straps and, using nylonpreventers, the strap legs would behogged in against the hull at the gun-whale to prevent fore and aft slippingof the slings. This basic plan wasachieved after some modification.

On the first working dive, twodivers scoured out mud around thestern and succeeded in passing a3/4-inch wire messenger strap. It wasapparent that this was not the ideallocation for the final lift, but it wasall that was accessible under thecircumstances. It was conceivablethat the stern could be lifted out ofthe mud using another strap repassin a better location forward of thescrew between the shaft and hull.A messenger strap was also passedforward with much less difficulty.

On October 12, the lift strapswere connected to the messengerstraps and, using the mobile cranes,the straps were rendered around thehull and connected to the spreaderbars. The lifting legs were secured atthe gunwhale to prevent fore and aftmovement. The lift then com-menced. As the stern came up, theboat began to slip aft, causing theforward strap to chafe against thepilings and part the preventers. Thisallowed the forward strap to startslipping. The friction of the star-board side against the pilings causedthe boat to render around in theslings to approximately 40 degreesstarboard. The forward sling ulti-mately slipped off and the boatrighted. It was now apparent thatthe forward sling had to go fartheraft and the aft sling had to go fartherforward to prevent rendering.

Since the boat was steel hulled,it was calculated that spreader bars

would not be required to limitlateral compression on the hull.(Aluminum boats would not with-stand this force without damage.)The increased lateral pressure on thehull would keep it from rolling.Using a 2-inch wire strap passedthrough the bullnose, the bow waslisted until it was in sight at the sur-face with the stern still resting on thebottom. The lifting strap was noweasily repositioned. The bow wasset back down on the bottom. Thesame procedure was repeated at thestern using the aft towing bitts asthe lift point. It was lifted just clearof the bottom and a lift strap waspassed forward of the screw betweenthe shaft and the hull, and the sternwas lowered back down.

The hook was disconnected fromthe strap on the towing H-bitts andreconnected to the repositionedstrap. All slack was now taken upon the rig, and 2-inch nylon pre-

Page 26: Fireboat has been lifted to surface. Above: Dewatering operations.

FACEPLATE 27

Dewatering continues on f/reboat.

venters were passed around theslings at the gunwhale to preventfore and aft slipping. All pumpswere started, and four swimmerswere standing by with 10-inch DCplugs to secure open port holes.Pumping teams were readied tocommence dewatering the boat uponsurfacing. A defueling pump truckwas also standing by. The craneswere repositioned so that the boatwould slide aft as it was lifted.

Lifting commenced at 2:45 p.m.As the boat came up, it slid graduallyaft (as anticipated) until it was clearof the finger pier. The mobile craneswere now able to "top up," bringingthe boat in next to the main pier.This maneuver also reduced the angleon the boom, alleviating problemsof the crane outriggers lifting off thedeck. At 3:05 p.m., the boat was onthe surface and dewatering, defuel-ing, and patching commenced. Patch-ing consisted of plugging the eightportholes with 10-inch DC plugs andmanufacturing a gasket for the sea-

chest cover plate, which was foundadrift in the bilges of the engineroom. At 1800, custody of the60-foot fireboat was turned overto the Naval Weapons Station, York-town, successfully concluding theoperation.

The rapid response and timelycompletion of this job demonstratedHCU-2's mobility, which is necessarywhen a potential ecological problemis present. In this case, it was avertedsince the fuel tanks, which contained800 gallons, stayed intact and water-tight. It also gave participating HCU-2 reserve units an excellentexperience in "reaction" salvage.

The new Aqua-air portable LP airsystem that has been procured forall Reserve Harbor Clearance UnitDetachments was ideal for thisoperation. Although only certifiedto support diving to 30 FSW, theunit will give reserve detachments anexcellent capability and has a defi-nite use in the active duty div-ing community.

The Reserve Harbor ClearanceDetachments have frequently aug-mented HCU-2 personnel on opera-tional commitments with total ef-fectiveness. This effort typifies theteam spirit and expertise underscor-ing the total viability of this reserveprogram. ®

Participating Personnel:

HCU-2

LCDRS. W. Delaplane(CO, HCU TWO)

LT(jg) F. P. Magaraci(Salvage Master)

BMC(DV) A. W. MoonBMC(DV) D. L. JongquistEM2(DV) A. G. TschidaEN2(DV) K. R. JobesBM2(DV) R. D. SmithBM1(DV)T. W. MilesEN3(DV) ). E. PattenaudeEM3(DV) Marie Carol Beatie

RHCU-2 DET506:

HTC(DV) PutnamRM1(DV) AndersonEO2(DV) BowmanBM3(DV) Stepura

RCHU-2 DET813:

CDRS. D. ChubbCDR J. F. MeyerLCDRN. K. MorrisonLCDR R. E. SaciaLT D. A. ShankLT C. B. LaporteSK2 J .Z . StajuieMM2 D. A. YostEN2 J.T. EstepIS2 R. J.Castro

SB FACEPLATE

Carpenter Stoppers:The History of Tlieir Use 21111! DevelopmentCAPT W. F. Searle, USN (Ret.)CDR T. N. Blockwick, USN (Ret.)

Mr. N. B. Davis

Introduction:Ever since the introduction of wire rope into U.S.

Naval service, the need for a device to hold or grip thisrope has existed. Over the years the U.S. Navy has usedcarpenter stoppers (also referred to as wire rope grips)to fill this need. As the Navy's applications for carpenterstoppers have become more demanding, a number ofoperational problems and failures have occurred. Tosolve these problems, the Navy has periodically madeimprovements in the design of this salvage tool.

The evolution of Navy stoppers can be grouped intothree generations: "old World War II (WW II) style,""improved 1948 style," and "modified-improved 1968style." The "old WW II style" and earlier stoppers werebasically made in accordance with James Carpenter's1899 U.S. patent. In 1948, a major redesign was per-formed at the former Boston Naval Shipyard (BNS).The most significant improvement made was shiftingfrom a cast steel to an all forged steel construction,because forged stoppers did not have the same cata-strophic tendency as cast stoppers to explode when sub-jected to shock or impact loads. The most recent im-provements were made in 1968, again at the BNS.These changes were fairly minor modifications of the1948 design.

As the new generations emerged, several attemptswere made to purge the older "obsolete" stoppers(specifically the "cast" WW II style) from the Navysupply system. However, these attempts met with onlylimited success. In fact, some of the unsafe stoppers,which were scrapped, were subsequently sold as surplusto the commercial market and are still in use today.

This article outlines the origin of the carpenterstopper and its development and evolution within theU.S. Navy. It discusses some of the problems and failures

of Navy stoppers over the years, including the diffi-culties encountered in purging the "old WW II style"stoppers from the Navy system. Finally, detailed descrip-tions and figures are presented for all three generationsof Navy stoppers, including the current U.S. Navystandard design ("mod-improved 1968 style").

Enough description is provided in this article toenable the positive identification of 1948 and 1968style Navy stoppers. The Navy has already been directedto destroy all its "old WW II style" stoppers and it ishoped that, in the interest of safety, commercial usersof these outdated "cast" stoppers will follow suit byremoving them from service and destroying them.

The Origin and Evolution of the Carpenter StopperWithin the U.S. Navy:

The carpenter stopper derives its name from itsinventor, James Carpenter of Portsmouth, England.Carpenter received a U.S. Patent (No. 639,520) in 1899for his "Apparatus for Holding Cables, Wire Ropes, andetc". The purpose of the device, according to the inven-tor was as follows:

"This invention relates to devices for holding wirerope; and it has for its object to provide a simpleand improved device of this character which willeffectively and automatically adjust itself to varia-tions in the strain on the rope and which can bereadily disengaged under the heaviest strain with-out any injury to the rope."

The British soon put this early carpenter stopper touse in various applications. Some years later, in a pre-WW II inspection visit to the U.K., the USN Supervisorof Salvage saw carpenter stoppers (sometimes calledBoullivant Clamps) in use and recommended that they

FACEPLATE 29

be added to the U.S. Navy's salvage equipment. Follow-ing his recommendation, the first U.S. Navy stopperswere built at the BNS using British plans and specifi-cations. These early stoppers were made from caststeel and provided only a relatively low gripping power.They were not intended to develop the full breakingstrength of the wire rope they gripped.

The U.S. Navy put these stoppers to use in salvagework, towing, and minesweeping. However, while theincreased use of wire rope made stoppers indispensible,they proved to be far from satisfactory when used insuch demanding applications. By the end of World WarII, it was clear that there was a need for a more reliableand efficient stopper. To this end, in August 1946, theBNS was tasked to undertake the development anddesign of an improved carpenter stopper. In addition,the development program was to include the design of asatisfactory adapter type stopper for use with two ormore sizes of wire rope. Although adapter stoppers weresuccessfully developed, they have not been used exten-sively and are therefore not discussed here in detail.Improved 1948 Style:

The first task of the development was to define whatthe general requirements of the new and improved car-penter stopper would be. They were as follows:

• The holding power would be equal to or greaterthan the yield strength of the wire rope used, i.e.,two-thirds of the ultimate strength of the rope.

• The stopper would hold the rope so that therewould be no permanent deformation to the rope.

• The stopper would open when under strain.• The size and weight of the stopper would be as

small as was compatible with its strength and dutyrequirements.

Next, a critical analysis of the design and methods ofmanufacture of the original stopper revealed the follow-ing primary reasons for its poor performance:

• Lack of protection of the wire rope under load,• Excessive friction between wedge and body, and• Low strength of parts.To correct these deficiencies, the BNS made the

following changes to the "old WW II style" stopper:• Length of Grip: The length of the gripping por-

tion of the smooth wedge block in the old stop-pers was in ratio varying from 6 to 1 to 8 to 1,compared to the rope diameter. The latter ratiowas used in proportioning the new stopper.

• Location of Pulling Eyes: In order to obtain adirect pull, the stopper eyes were raised to coin-cide with the rope centerline. They were alsomaterially strengthened by a more gradual fairinginto the stopper body.

• Cover: This was reinforced with ribs to preventbending under the high transverse loads. The hingepin hubs were extended to assist in carrying theinternal loads.

Lock: On the smaller sizes of stoppers, the orig-inal design of the lock was retained. On the largersizes a special design was evolved for safety as wellas convenience. To open, this type required aheavy downward blow on the cover locking lug.The striking surface at the top of the lock wasdesigned to deflect the hammer outside the pathof the suddenly released cover.Wedge: This part became a die forging and had itsrope grooves formed during the forging process.The grooves had a pitch (or lead) slightly greaterthan before to conform to that of the rope at itsgreatest amount of stretch. The cavity ends andhelix ridges were well rounded over to preventinjury to the rope. The forward end was bevelledto prevent "digging in" as it slid into the stopper.No shoulder was required at the large end since thegap opening determined the maximum amount oftravel. To resist indentation of the cavity by thewire rope, steel of a slightly greater hardness thanthe rope was used.Smooth Wedge Block: To resist scoring andabrasion of the cavity by the wire rope, steel ofnearly the hardness of the rope was used. How-ever, by using a steel somewhat softer than thewire rope, abrasion of the rope was avoided.Forgings: To obtain the maximum strength, allbody parts were drop forged instead of cast. Inthe design of the different parts, every effort wasmade to eliminate any undesirable local stressing.All corners, fillets, and adjacent surfaces were wellrounded and faired for maximum strength.

Figure 1 "OLDWW II STYLE"Navy Carpenter Stopper

30 FACEPLATE

The stopper resulting from these changes is referredto as the "improved 1948 style." The two most signifi-cant changes were the shift from (somewhat brittle)cast steel to tougher forged steel construction and theaddition of reinforcing ribs on the stopper cover.

Tests were conducted to assure that the improvedstopper met all the general requirements that had beenformulated. It did—the most notable of which wasthat of weight. The stopper was shown to have a safetyfactor of 2 at the ultimate breaking strength of the wirerope. Such close design attested to the fact that theweight of the stopper had been made as small as possibleconsistent with the strength and duty requirements.This was favorable because the reduced weight wouldfacilitate handling and use at sea where the conventional5:1 factor of safety could not be afforded. The "im-proved 1948 style" carpenter stopper truly proved tobe more efficient.

For a number of years, "improved 1948 style" stop-pers were manufactured at the BNS and used throughoutthe Navy. Each stopper that was made at the BNS wastested. This included a proof test and a release underreduced load. After a stopper passed, it was stampedwith "BNS" and the date of test.Modified-lmproved 1968 Style:

In the 1950's there occurred at least two noteworthyfailures of carpenter stoppers during employment on asalvage job. During subsequent series of tests at the BNS,several weaknesses were revealed which would result inoperational failure of the stopper and bridle under highloads. These material and design deficiencies led to thefollowing failures during testing:

• A shear failure of the hinged cover under highloading,

• Bending of the cover hinge pin and deformationof the cover hinge pin holes and loose wedgeblock,

• Scoring and galling of the wedge bearing stripand shearing of its retaining screws,

• Shearing of the wedge retaing screw in the largersize stoppers, and

• Failure of the rope in the wire rope bridle.Because of the outcome of these tests, the BNS was

in 1968 once again tasked to evaluate the existing car-penter stopper design. Following the evaluation, BNSrecommended that to alleviate the causes for carpenterstopper damage and thus improve operational reliability,it would be necessary to:

• Initiate quality control procedures during themanufacture of carpenter stopper parts to ensurethat stress concentrations such as those causingcover failures would be prevented.

• Modify the loose wedge block and cover with ashelf for an energy absorbing pad and an impactsurface, respectively. This included making thecover hinge continuous. In this way, deformation

Figure 2 "IMPROVED 1948 STYLE"Navy Carpenter Stopper

of the cover hinge pin and associated damagewould be prevented when a loaded stopper isopened.

• Use a suitable extreme pressure lubricant on thewedge-bearing strip interface and ensure that thecarpenter stopper is correctly lubricated beforeeach operation. A molybdenum disulfide pastetype lubricant was recommended.

• Provide an abraded surface for the bearing striploose wedge block interface.

• Change the material requirements for wedgeretaining screws to MIL-S-890, Alloy No. 2 forincreased strength and add a second retainingscrew on the opposite side of the wedge on car-penter stoppers of size 5/8-inch and larger.

• Use only independent wire rope core (IWRC)rope of 6 X 37 WARRINGTON-SEALE construc-tion in the fabrication of wire rope bridles toprovide the strand support, flexibility, andstrength required.

These recommendations were incorporated intoseveral carpenter stoppers which were subjected to ex-tensive testing. The program's end product was the"modified-improved 1968 style" carpenter stopper,which could be safely and repeatedly operated up tothe wire rope's breaking strength. This stopper has beenadopted as the standard U.S. Navy design and is coveredby Military Specification MIL-S-24584. It does not dif-fer markedly in appearance from the "improved 1948style."

The final task of the BNS, accompanying the stopperimprovements, was the preparation of two additionaldocuments: 1) "Carpenter Stopper, Operation andMaintenance Instructions-Technical Manual" (NAV-SHIPS 0994-004-8010) and 2) "Wire Rope for Use withCarpenter Stoppers" (BNS Report No. TR - 57). Both ofthese documents are available through NTIS.

FACEPLATE 31

Discussion of Problems and Failures:The culmination of over 30 years of work by the

U.S. Navy has resulted in a carpenter stopper that is aneffective and efficient device for gripping and holdingvarious sizes of wire rope. This effort, however, has notbeen without problems. The forging, machining, andtesting of each stopper has been costly. Also, with theclosing of the BNS in 1973, the Navy ceased to manu-facture carpenter stoppers; yet the Navy still requiresand regularly uses carpenter stoppers in towing, lifting,and ship salvage (both surface and submarine).

Heretofore, this discussion has been related to U.S.Navy carpenter stoppers. It is thus prudent to point outthat carpenter stoppers have also been made commer-cially and used extensively throughout the world. Thecarpenter stopper principle is routinely used in mech-anisms such as hydraulic pullers and wire holding de-vices. In most operational uses, the requirements arenot as rigorous as those of the Navy. Therefore, com-mercial stoppers generally are manufactured and testedto different specifications and plans. Often, these stop-pers are cast rather than forged because of lower cost.It is therefore common practice to use a 5:1 safety fac-tor (much higher than the Navy's typical 2:1) to com-pensate for the poorer impact strength characteristics ofcast steel. Unfortunately, this 5:1 safety factor is some-times inadequate to prevent brittle fracture under thesevere dynamic loads encountered in offshore opera-tions.

There have been failures of carpenter stoppers incommercial use recently. In some cases the stopper hasliterally "exploded." It is not known for sure whetherthese failed stoppers were originally Navy stoppers orcommercial cast types. However, these is a good possi-bility that some of the failures were due to the use of"old WW II style" Navy stoppers.

The following is a possible chain of events leading tosome of these commercial stopper failures. When theBNS completed the development of the "improved 1948style" stopper, all "old WW II style" stoppers werereplaced with the newly designed ones. The "old WW IIstyle" stoppers were disposed of as surplus. As a resultmany appeared in commercial channels. In fact, somewere eventually sold back to the Navy and reappearedon the Navy's supply shelves. While the Navy has re-purged these "old WW II style" stoppers again, thistime with direction to destroy them, it is likely thatsome of these obsolete and unsafe cast stoppers willexist in commercial salvage equipment pools—an acci-dent just waiting to happen! It is therefore most im-portant that these stoppers be identified and destroyed.

The salient identifying feature of the "old WW IIStyle" stopper is its flat hinged cover (see Figure 1) ascompared to the ribbed cover of the "improved 1948"and "mod-improved 1968" stoppers. The shape of thestopper bridle ears are also a give-away. None of the cast

steel stoppers had the elongated ear reinforcement thatis characteristic of only forged assemblies (see Figure 2).The most important deficiency of the "old WW IIstyle" stopper is the fact that it is "cast" steel and thushighly susceptible to brittle fracture when subjected toan impact load.Description of Carpenter Stoppers:

Old WW II Style: These stoppers have flat, unribbedhinged covers (See Figure 1) and were manufactured bythe BNS until replaced by the "improved 1948 style"stopper. Because of their cast steel construction, thesestoppers are no longer authorized for and have thusbeen removed from U.S. Navy service.

Improved 1948 Style: These stoppers, shown inFigures 2 and 3, have characteristically ribbed hingedcovers. They were also manufactured and tested at theBNS. "Improved 1948 style" stoppers are completelyforged from steel and, while they can be improved uponby incorporating the 1968 modifications, they are stillauthorized for Navy service. Most of the carpenterstoppers in use today by the U.S. Navy are of the "im-proved 1948 style." All Navy-built carpenter stoppers ofthe "improved 1948 style" are clearly stamped "BNS"and date of manufacture.

Modified-lmproved 1968 Style: These stoppers arealmost identical in appearance to the 1948 style stoppershowever, several subtle differences exist. On 1968 stop-

Figure 3 "IMPROVED 1948 STYLE" Carpenter Stopper Assembly

33 FACEPLATE

pers of 5/8-inch and larger, a second retaining screw hasbeen added on the opposite side of the wedge. Also on1968 stoppers of 1-3/8-inches and larger, a rubberenergy absorbing pad has been added to the loose coverhinge pin when the stopper is opened under load. Fur-ther, the cover hinge has been made continuous. Finally,the test date stamped on "mod-improved 1968 style"stoppers would be 1968-1973. Because the BNS wasclosed in 1973, only a few 1968 stoppers were madethere. Current procurement at Baldt is, however, to thisdesign.

Figure 4 illustrates the general assembly of the "mod-improved 1968 style" carpenter stopper. This stopperis composed of five basic high strength alloy steel forg-ings: (1) hinged cover, (2) smooth wedge block, (3)loose wedge block, (4) the wedge, and (5) the coverlock. The loose and smooth wedge blocks are joinedtogether by the hinge pin (6), which is retained by a pin(7). The cover is joined to the loose wedge block by thecover hinge pin (8), which is retained by a pin (9). Thecover lock is joined to the smooth wedge block by thelock hinge pin (10), which is retained by a pin (11). Thebearing strip (12) is secured to the loose wedge block byfour countersunk screws (13) staked in position. Thewedge is retained by retaining screws (14) and (15) onall stoppers 5/8-inch and larger; however, smaller stop-pers have only screw (15). The cover lock is secured ina closed position to the cover by means of the lockingpin (16). The locking pin is secured to the lock hingepin by means of wire rope (17) and two swaging sleeves(18).

Carpenter stoppers manufactured after 1969 in sizes1-3/8-inches and greater have a rubber pad (19) installedon the loose wedge block. The rubber pad is retained byfour countersunk screws (20). Note that the assembly ofthe "improved 1948 style" stopper is the same as shownin Figure 4 minus parts (14), (19), and (20). Also notethe change in the cover hinge (1) from 1948 (Figure 3)to 1968 (Figure 4).

Adapter Type Stopper - Mod-Improved 1968 Style:The construction of the adapter type carpenter stopper(see Figure 5) is similar to the "mod-improved 1968style" carpenter stopper. In place of the smooth wedgeblock of the standard carpenter stopper there is an adap-ter block (21). There are four adapters (22) for differentsizes of wire rope. The adapters are secured to the adap-ter block by means of two screws (23). There are fourwedges (24) for different sizes of wire rope. The wedgesare retained in a manner identical to the 1968 carpenterstopper. While the adapter style carpenter stopper hasproved to be a successful design, it has not been widelymanufactured. It is not used frequently.

All U.S. Navy carpenter stoppers are identified withtheir respective size by an inscription on the side of thesliding wedge.

Figure 4 "MODIFIED-IMPROVED 1968 STYLE"Carpenter Stopper Assembly

Figure 5 "MODIFIED-IMPROVED 1 968 STYLE"Adapter Type Carpenter Stopper

Assembly

FACEPLATE 33

Figure 6 Wire Rope Bridle Assembly

Description of Equalizing Bridles:An equalizing bridle is an integral part of any car-

penter stopper. Without it, a balanced load can not beapplied to the wire rope under tension. For this reason,the two primary types of bridles, wire rope and chain,are described below.

Wire Rope Bridle: The wire rope bridle, shown inFigure 6, comprises three basic high strength alloy steelforgings permanently assembled together on a length ofwire rope (1). These parts are the equalizing thimble (2)and two sockets (3). The sockets are secured to the wirerope with zinc poured plugs. The shackle (4) is securedto the equalizing thimble by the shackle pin (5). Twosocket pins (6) are secured in the sockets by lock nuts(7).

Chain Bridle: The chain bridle is an alternative to thewire rope bridle. While some chain bridles do exist inthe Navy's Emergency Ship Salvage Material (ESSM)Pools, they are infrequently used. This is primarilybecause of their greater weight and handling difficulty.Summary:

This paper provides adequate information to identify"old WW II style" Navy carpenter stoppers. A briefdevelopment history has been provided so that thedifficulties inherent in the design, fabrication, and use of

this highly loaded component can be appreciated.It goes without saying that the maintenance and operat-ing aspects are of great importance if carpenter stoppersare to be safe and effective pieces of equipment. It isbelieved that the difficulties and problems encounteredin the development of this stopper by the Navy will pro-vide valuable information for the design, fabrication,testing, and use of carpenter stoppers and related equip-ment by the Government and commercial enterprises.Because of the low safety factors and high loadings nor-mally associated with ship salvage, it is particularlyimportant to identify "old WW II style" or other in-adequate cast carpenter stoppers to prevent disastrousconsequences in the course of these operations. Speci-fically, it should be ascertained whether a stopper isforged or of cast construction. If it is the latter, it shouldnot be used for high load applications such as ship sal-vage and similar operations. __ _____

Editor's Note:This article was prepared gratuitously by the authors

as a public service. It is based on their nearly 75 man-years of experience with carpenter stoppers.

CAPT Bill Searle will be remembered by manyreaders as the Philippine Area Salvage Officer (1954-'56), Engineering and Research Officer at the NavyExperimental Diving Unit (NEDU, 1956-'59), PacificFleet Salvage Officer (1962-'64), and as the Supervisorof Salvage (1964-'69). Since retirement in 1970, CAPTSearle has served both as a Senior Visiting Lecturer atthe Massachusetts Institute of Technology and asa consultant. He is Chairman of the firm Searle Con-sortium, Ltd., international consultants in ocean engi-neering, ship salvage, diving, towing, and rigging.

CDR Tom Blockwick became involved with Navysalvage during World War II, when in 1942 he attendedthe original U.S. Naval School, Salvage, at Pier 88 inNew York, alongside the sunken liner NORMANDIE.He participated in various harbor clearance operations inNorth Africa, Europe, and the western Pacific. He wasEngineering and Research Officer at NEDU (1947-'51);Technical Officer of JTF 7.3, involving deep oceanmoorings and salvage related to weapons testing (1959-'-61); Seventh Fleet Salvage Officer (1961-'64); and Chiefof Production Engineering at the Boston Naval Ship-yard (1964-'66). He will be especially remembered asSite Commander of SEALAB II. During his tour at BNS,he and CAPT Searle (then SUPSALV), initiated andmanaged the project which led to the 1968 modifica-tions to the Navy carpenter stoppers. Since retiring in1966, CDR Blockwick has been involved in variousocean engineering, salvage, towing, and ocean mooringprojects at General Electric Co., Ocean Systems Inc.,and Searle Consortium Ltd. He is currently SeniorOcean Engineer at Mar Inc., Rockville, Maryland.

Brye Davis has both a BS degree in MechanicalEngineering and an MS degree in Ocean Engineeringfrom MIT, where he studied under and participated insummer projects afloat with CAPT Searle. After gradu-ation in 1978, he served as an Ocean Engineer withSeaward International Inc., of Falls Church, Virginia,and Searle Consortium Ltd. Since 1980, he has beenan Ocean Engineer with Mar Inc., where he specializesin mooring, salvage, and towing components and sys-tems design. ____ ______________

3<» FACEPLATE

1Generally, when a serious recompression

treatment or diving-related matter arises, you, asthe individual charged with diver supervision, donot hesitate to seek professional guidance orassistance. It is well known that a telephone call,day or night, to the Navy Experimental DivingUnit (NEDU) will put you into direct contactwith a staff of qualified and experienced hyper-baric medical experts who are committed toquick-response advice and/or solution to yourproblem.

Besides diving medical inquiries, however,NEDU handles many other concerns related tooverall diver well-being, including recompressionchambers; diving apparatus and apparel; compres-sors, filters, and storage flasks; hyperbaric plumb-ing, components, lubricants, and cleaning.

For the most part, Navy personnel responsiblefor diving safety are knowledgeable and experi-enced and are routinely guided by official Navypublications such as the Diving Manual. Oftenwhen in doubt, they will go to NAVSEA orNAVFAC in search of technical answers. In asmany cases, though, they hesitate to ask for assis-tance at the headquarters level because of profes-sional pride or concern with the thought thatcalling on the certification authority might ad-versely affect their particular system or opera-tional situation. As a result, problems thoughtsolved by a "best guess" or "seat-of-the-pants"approach later re-occur, sometimes with danger-ous consequences.

In addition to a staff of medical experts, NEDUhas a team of hyperbaric experts who continuallyprovide technical and operational guidance to theFleet in diving. Consisting of Master Divers, DivingOfficers, test engineers, and hyperbaric specialists,this team understands your immediate need forthe direct, no-hassle approach to your divingproblems on hardware and procedural matters.

Each year, NEDU spends many man hours ontesting and evaluating diving support hardware.Included recently are new commercial SCUBAregulators, compressors, filters, life vests, depthgauges, the decompression computer, the Mk 12SSDS mixed-gas mode, the Mk 14 CCSDS, a diverrespiratory gas heater, and a new recompressionchamber, to name a few.

In the area of procedures, NEDU conducts agreat number of controlled manned dives yearlyin the Ocean Simulation Facility (OSF) Hyper-baric Chamber Complex to optimize decompres-sion schedules and saturation excursion limits andto test and validate new breathing mixtures. All ofthis is designed to extend our diving capabilitiesboth shallow and deep and to provide greater diversafety and versatility through revisions to theDiving Manual, decompression tables, and otherdiving-related and safety reference documents andpublications.

NEDU provides answers to the Fleet on divingtechnical problems or direction as to where theanswers may be found. In addition, NEDU servesas a clearing house point-of-contact where theFleet sailor may bring, and in fact is urged tosubmit, his ideas and beneficial suggestions as acontribution to a safer and better Navy DivingCommunity.

"Service to the Fleet" remains NEDU's proud-est and most concerning mission function. Forroutine matters, NEDU may be contacted throughthe Office of the Supervisor of Diving, Naval SeaSystems Command, autovon: 227-7606 or com-mercial: (202) 697-7606. Urgent matters may bereferred directly to NEDU at autovon: 4364351or commercial: (904) 234-4351. NEDU's mailingaddress is:

The Commanding OfficerNavy Experimental Diving UnitPanama City, Florida 32407

FACEPLATE 3E

DEPARTMENT OF THE NAVYNAVAL SEA SYSTEMS COMMAND

WASHINGTON, DC 20362

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