DEVELOPMENT OF A VALUE-ENGINEERED NOMAD BUOY GeraldTimpe (LT) William 0. Rainnie,Jr. U.S. CoastGuard NOAA Data Buoy Office NOAA Data Buoy Office National Space TechnologyLaboratories NSTL Station, MS 39529 NSTL Station, MS 39529 ABSTRACT In July 1946, theBureau of Ships became involved in a program todevelop automatic weather station Sincethe mid-1970s, the National Oceanic andAtmo- buoys. As a perspectivepart of this program,they sphericAdministration (NOAA) Data Buoy Office requested DTM8 to conduct a preliminaryinvestiga- (NDBO) hasused Navy OceanographicMeteorological tioninto the feasibility of mooring a buoy, simi- AutomaticDevice (NOMAD) buoys as partof their lar to Buoy By in 3600 ft ofwater with a 3-kncur- oceandata gathering network. These U.S. Navy- rent.3This investigation concluded that a hull built,20-ft long, boat-shaped hulls, have proven thesize of Buoy B couldnot support the static to beextremely seaworthy buoys. The hullsare weightof an anchor lineof sufficient length to be reliable,easily transportable, and for many appli- moored in 3600 ft ofwater. To supportsuch a cations,they are an attractivealternative to the mooring, a similar shaped hull had to be 20-ftlong conventional40-ft and 33-ftdiameter discus-shaped and displaceapproximately 20,000 lb.This was to buoys. As a result, NDBO, inearly 1979,began become theprototype of the buoy now calledthe activelypursuing the idea of designing and con- NOMAD. structing a secondgeneration, value-engineered (VE) version of the NOMAD buoy. A consulting firm In 1952, thefirst NOMAD buoy, NOMAD-1, was built was contractedto redesign the NOMAD hull, and in accordinglyspecifications to prepared by June1981, construction was started on a series of DTMB,3,4 and was deliveredNationaltheto five new NOMAD buoys.This paper describes the Bureau of Standards (NBS), who was taskedwith the design and constructionof the VE NOMAD buoy, and jobof evaluating the buoy.5 From 1954 to 1971, detailsthe efforts of industry and government 20 additional NOMAD hulls were built and subse- workingtogether to produce a reliable,cost effec- quentlyoperated by the NBS, Naval Air System Com- tive data buoy. mand, and NavalUnderwater Systems Center (NUSC), withfavorable results.6-9 NOMAD DEVELOPMENT 20-ft NOMAD VS 40-ft DISCUS The NOMAD hullis we1 1-documented to have been develo ed fromthe "Roberts buoy" or "current radio In 1959, atthe behest ofthe Office ofNaval buoy."!-3 The Robertsbuoy was a 6.67-ft Research (ONR), theConvair Division ofGeneral long,400-lb, boat-shaped buoy developed inthe Dynamics (GO) Corporation was contractedto gener- early 1940s,by the U.S. Coast and GeodeticSurvey, atethedesign of a eneralpurpose telemetry to measure strongtidal currents. The buoy'sper- oceanographic buoy?lO,yl distancelong for formance was satisfactory,but its limited size (2500mi) transmissions of HF radiodata. The restrictedthe buoy's use inother areas. designcriteria called for the survival of the buoy inthe following environmental conditions: current The successortothe Roberts buoy was theNaval velocityof 10 kn, windvelocity of 150kn, 60-ft ResearchLaboratory (NRL)Mark 3 buoy.This hull highbreaking wave, and an unspecifiedice loading. was designed by NRL forhousing sono-radio equip- Model tests wereconducted on tencandidate hull ment,moored in a strongcurrent in deep water. It forms,with Preliminary indications showing that was 12.58-ftlong and displacedapproximately 4700 thetwo leading contenders were the 40-ft discus lb. The buoy resembledthe Roberts buoy, but with buoy and the NOMAD. In 1965, it was concludedthat increaseddimensions to accommodatea largerpay- the40-ft 200,000 lbdiscus buoy was thebest load.There were two tentative designs of the NRL choice, and, as a result,the "Monster Buoy" was Mark 3 buoy, designated Buoy A andBuoy B. The two developed. The NOMAD hull was rejectedprincipally designshad the same dimensionsin plane; however, becausethe buoy's excessive rollmotion resulted Buoy B had an approximately8-in. greater draft inhigh antennaradiation losses, and alsobecause than Buoy A. NRL taskedthe David Taylor Model thehull was notsymmetrical. Another problem with Basin (DTMB) to conductmodel tests on bothhull the NOMAD (althoughnot mentioned inthe refer- typ es to determinetypes to their performance.2 The ences) was thebuoy's relatively small displaced resultsof these model tests caused DTMB to recom- volume. Inthe mid-1960s when the"Monster Buoy" mend thefurther development of Buoy B because of was conceived,the vacuum tubeelectronics used for itsgreater load-carrying capacity. dataprocessing and transmissionrequired diesel or 605 US. Government work not protected by US. copyright. propanemotor generators to provide the necessary requiredforpresent and perspective NDBO buoy power. It wouldhave been impossibleto fit such a sites. These studiesconcluded that discus buoys powersystem intothe confines of a NOMAD hull. as large as49 ft mightnot survive on some north- Today, integratedcircuits and CMOS technologyhave ernPacific and northernAtlantic sites. drasticallyreduced the power requirements.This, coupledwith the use of the UHF satellite communi- cations, has eliminated,for NDBO's use, thepre- In December1978, NDBO sponsored a "SevereEnviron- viousobjections to the NOMAD hull. mentNorkshop" todiscuss the problem of discus buoy'scapsizing in a severeenvironment and to seek possiblesolutions.16 Among the many con- THE NOMAD AND NDBO clusions of theworkshop were that 40-ft buoys should be used inlieu of 33-ft buoys in severe InJuly 1974, NUSC transferredthree NOMADS to NDBO sites, and solidballast should beused inlieu of forevaluation and use, followed by thefive more waterball ast for 33-ft hulls on severesites. It hullsin June1975. NDBO has sinceacquired title was furthersuggested that the NOMAD buoy should be to 15 ofthe 21 NOMAD buoys built. Of these 15 considered as a possiblesolution tothe severe hulls,14 are still in use inthe NDBO buoyinven- environmentproblem. Intheir many yearsof use, tory. One hull,designated 6N9, brokeits mooring no capsizingof mooreda NOMAD has beenknown to offthe New Jerseycoast in October 1980,and was occur. subsequentlylost at sea.The final NOMAD buoy acquired came fromWashington, DC Navy Yard in NDBO fostered and seriouslypursued the possibility 1981, and isbelieved to be thefirst NOMAD built, of the NOMAD as a solutionto the severe environ- NOMAD-1. mentproblem. In 1979,a NOMAD was moored nextto a 40-ft buoy at 45.9"N latitude and 131.1"W longi- tude,the site of the first 33-ft buoy capsizing. The objective was two-fold:to test for the sur- The NOMAD hull has become a reliablepart of NDBO's vivabilityof the buoy and instruments and to check hullinventory. Infact, in many areas,such as theresulting data quality. A mooringfailure cut cost and ease oftransportation, the NOMAD is a shortthe experiment, but sufficient data were col- superiorhull to NDBO's 40-ft and 33-ftdiscus lectedto indicate that the NOMAD satisfiedboth of buoys. NOMAD hullsare smal ler and cheaper to thetest requirements. Subsequently, the NOMAD was buildthan the larger discus hulls. In 1981, the independentlydeployed at the site, and duringthat priceof a NOMAD hull was roughly 20 percent of periodsignificant wave heights as large as 33 ft thatof a 40-ftdiscus. In addition, the biannual wereencountered. This test, combined with mooring maintenancecost of an aluminum NOMAD isless than design changes that expanded the use ofinverse halfof that of the large discus buoys. There are catenarytype moorings,17 led theto tentative alsoeconomical advantages otherin areas. The conclusionthat the NOMAD buoy was capableof NOMAD'S smallsize makes the buoy transportable by replacing a 40-ftor33-ft hull anyon site. truckor rail, whereas thelarge discus hulls must Because ofthis, the decision wasmade notto build betowed or transported by shipfrom location to 40-ftor 49-ft hulls as severeenvironment buoys, location. The reduceddrag ona NOMAD hullpermits and instead go forwardwith the design and procure- theuse of smaller, moreeconomical mooring compo- ment of a second generation NOMAD buoy.However, nents.In spite of itsbeing an unsymmetricalbuoy onlyyears of experience with NOMAD buoys in severe withonly a 15-ftinstrument height, the NOMAD pro- environments will answer thequestion. ducesdata quality (including one-dimensional wave data)equivalent to the larger discus buoy. There may be limitations on directional wave measurement due tothe hull's being nonsymmetrical, but this VE NOMAD DESIGN problem is understudy. Due toits smaller size, the NOMAD isslightly more vulnerableto collision In June1979, NDBO contractedthe consulting firm and vandalismthan the larger discus hull; however, ofChi Associates, Inc., to examinethe original all-in-all,the NOMAD'S advantages faroutweigh its NOMAD buoydesign and suggestpossible modifica- disadvantages. tionsto the design to reduce the buoy's fabrica- tioncost. The ChiAssociates work was performed inthree stages. First, given the operating envi- ronments theof buoys,Chi Associates was to SEVERE ENVIRONMENT BUOY developthe design criteria for the VE NOMAD. The resultantdesign criteria, detailed inTable 1, In a four-yearperiod, five of NDBO's discusbuoys followsthe same generallines as thedesign cri- havecapsized during severe weather events. Three teria developed for NDBO's VE 33-ftdiscus buoys. ofthese were 33-ftbuoys that capsized while Second, theoriginal structural design was modified moored inthe North Pacific. Onewas a 40-ft buoy slightly,after which the