TECHNISCHE UNIVERSITEFT -L.zL TS'- r-1 Laboratoriurn voor Humaq;kpwç:Scheepshyrcmechanjca 1 Watercraft L. Tel.: 015- 773 - Fax: 015- 751838 1/L- ky.1tI In striving for ever higher speeds the flimiliar racing shells propelled by eight oarsrn en may have to give wato LW con yen rional wa cercra ft. Such a record-setting vehicle was designed and built by the a ud2ors
by Alec N. Brooks, Allan V. Abbott and David Gordon Wilson C .w c )
nih recently the slender shells. not experience any yertical accelera-craft's operators are no:likelyto or racing rowboats, made fa-tion, lift is equal to weight. beoverweight (assuming theyare miliar by the Olympic Games, For most watercraft lift is generatedhealthy, athletic individuals to begin the races on the Thames River in En- by buoyancy: the displacement of wa-with), the weight reduction must apply gland and other rowing regattas heldter by the craft's hull. The lift is equalprimarily to the vehicle itself. throughout the world, were the fastest to the weight of the water displaced, Efforts to this end have led to racing human-powered watercraft. The fast-and it operates even in the absence ofshells that weigh only a small fraction est of these, powered by a crew of eightmotion. In addton many high-speedof the opera:ors weighta relation oarsmen, achieve speeds of 12 knotsboats take advantage of dynamic lift.similar to that of a modern racing bi- over a standard 2,000-meter course.which is produced as the boat movescycle and its rider. In the past shells (One knot is equal to about half a me- through water. A common example of\vere generally made of cedar, spruce ter per second.) Human-powered we-dynamic lift is planing: when the bot-and mahogany, and they were made tercraft that are not bound by the ar-tom of the hull continuously deflectslighter by thinnirtg their hulls. (Indeed, bitrarv restrictions of officially sanc-water down'.vard so that lift is pro-the term "shell" arose because a care- tioned rowing events arelikelyto duced as a reaction force .:\boat thatless finger could easily puncture a equal or surpass this level of perfor-relies on planing for most of its lift wood hull.) In the 1950's experimental mance. Designers of these unconven- rides higher in the wateroften right atshells that had a skirt oi glass-flber- tional craft are disrensing \vith oars the surfaceand requires less buoyan- reinforced plastic were tried, and by and taking full ad';arttnge of moderncy. Until recently designers of human-the end of the 1960's commercial!. high-efficiency propellers. They are powered vatercraIt had not been ableavailable composite-based boats had even dispensing with hulls as theex- to SUCCC5Siifli incorporate dnamccchallenged :he dominant positton of plore innovative ways to reduce the re- hit mato their vehmcles. wood boats in rowing cu'cles. Toda'. sistance ainst motion, called drag. Thrust is the force (produced by thethe wood sacilis becoming a rar- that water exerts on a moving boat. actions of the operator in the case ofitv. Soohisticated comoosite materials fndd. two ofus (Brooks andhuman-powered watercriaf:) that pro- Lorsistineo re \i" ,-'bbott) have developed just such apels the craft. Drag is the force that bywith tioers Ci C polymer ororai;ide record-setting human-po'.vered water- definition acts in the direction oppo-have brouehtetown ate ue:gnt ot toe craft. The craft.iii,i' Fish I!. is rid-site to the direction of the craft's mo- ligiatest s;nge-person sheil to less titan den like a bicycle. I: has a pair otT hy- tion. If a coat is moving at a steady LU Kilograms. clrofoils, or ander'.vater wingz. and a speed, the thrust is equal to the drag. Itt high-efficiency propeller. It enables asummary. at constant speed lift bai- ssiiming that the weight of the rue- singie rider to complete a 2,000-meter ances weigh: and thrust balances drag. 1. ing she! nas been reduccd to course siniflcancly faster than a single In order to translate efficiently apractical minin'J.:m, a dsignars rower in a shell can, and it has attained given human po'er input into speedlion must turn to other wnys of a maximum speed of 13 knot.s over the most imçcrtant objective is to rain- imizing drag. Shellsha'. e'.vhatac short distances. imize drag. One oh'. ions way to lessen called disriaceraer,s hulls: vir:aailv a: drag is to reduce the '.vciht of the their lift is rrod uced by trie huovanc ceardiess rjf desienwhether it is boat. Once a boat begins to move. :ms of the huh. Displacement hulls h.:' -: crude rlotation deicc ropeiledsource of liii airnotal'.' ass exact.;Inc uraque P:operzthat ther draat' b underwater kicking, a wood rafta drag reit:zy. By rn:nimiztns proaciles :e:o Cs tacit spec:l tiiOuf pushed alont h'poles, a dultout Ca- ',vetont 01 the Doat the requirea ltttt the water urraches zero. }-lcn:e a noc PC'.arCu b. padalcs or rcducd. and hnce the draz as.;oc.:t-'-ctV lOW s::ees displa:cracn:-:...... tao. ed forv. at! s':.ecaing 'earsev- ed '..'ith the lift is lessened. Since :ae 'r,iaies have ex:ren:etyIs L.,aa cr. '.vatrcrn(t rut:st eotitcad '.'i'.:t four baie OrCCs:.veight.lIft.thrust and '.rag. Wih: and lift are the simplest .-\'IONG THE FASTEST munn-povrid -atercra(t areo':rmtic':al ni:i:, cetounacrs:ai'id. \Ve ight isia1pll. the authors' uiico:, e':cion:,I ve:ici.'t,:[ih ii. The shcii. si'wn hertiu ret the gra.ita:ionnl force nulling down :our-rirne ()lv;npii Jnh:i ":tn131',;n.ve 'uilby .\tIrd St.irnprli .'.G u So on the craft apd its occul.'ant.: Ilit :s l-ivinFTiJz ii. ri.idu: by 'iet:heauth' i..'hb,tti. h.)s,irCd bap'i.t!-c'.:ii'n p thc force tha: ac:. up.:ard. oi:ntcract- pdller -jndi:pi'orred Stwo h drotoi s. r iihrwtcr ,s.c b1,:tcizI;. iits .i: the v. eight. ;'long ::.i hut does :ctu.iLv :G-J.e :'.e .'.ver turmaee and ur-;ne'ant ts:ps'': rue .rai': .n!. et I.",'-c- ::1-% ,..:'
are among the most elficierit of all ve-er the vetted surface area, the greaterwhich the flowischaotic andun- hicles. Racing shells, however, do notthe drag caused by the friction of the steady. Laminar boundary layers pro- operate at low speeds. water as it flows past the surface of the duce much less skin-friction drag than As a shell's speed increases, its draghull. This type of drag is known asturbulent boundary layers do. The increases dramatically owing in part toskin-friction drag. Hence as a boat isboundary layer on a shell is laminar at the formation of waves that emanatemade more slender, wave drag dimin- the bow, but only a short distance back from the bow and stern. The energyishes but skin-friction drag then be-from the bow it typically undergoes a needed to produce these waves is man-comes more of a problem. transition to turbulent flow. Drag is ifested as wave drag. Wave drag in- A hull designed for speedy boatssignificantly reduced if the transition creases rapidly with increasing speedmust therefore be shaped to minimize is delayed, thereby increasing the area but in an uneven fashion because thethe sum of wave and skin-friction of laminar flow on the hull. bow wave can interact constructivelydrag. Shells are designed to compete One method of extending the lami- with the stern wave (so that the wavesin six-to-seven-minute races at powernar boundary layer that is applied in are in phase and reinforce one anoth- levels of about half a horsepower persome specialized underwater vehicles er) or destructively (so that the wavesrower. (One horsepower is equal to ap- is the injection of long-chain polymers are out of phase and tend to cancel oneproximately 750 watts.) The resulting (sometimes referred to as slippery Wa- another) as the craft picks up speed. Atoptimal length-to-width ratios of these ter) into the boundary layer near the a speed called hull speed the bow is atsleek crait exceed 30. A single-oersoafront of the craft. Race-sanctioning or- the crest and the stern is at the troughshell, for example, has a length of be- ganizations are not likely to allow this of a single wave; in its passage throughtween eight and nine meters and a practice in competition, if for no other the water the hull has literally createdwidth of no more than U centimeters. reason than that it pollutes the water. a hill of water through which the boatIout that the optimal shellA similar anproach that might be al- must push. At this point a great expen-shape results in a skewed distributionlowed, however, would entail careful- diture of power is needed to increaseof drag at racing speeds: 80 percent ofly cultivating a 1a'er of naturally slimy the boat's speed. The human powerthe drag operating on the shell is due algae or some other innocuous micro-p plant cannot supply the required ef-- to skin friction and 20 percent is due to organisms on the hull. fort, and so hull speed acts as the effec-wave production. Boundary-Jayer suction is another tive speed limit of a human-powered technique that has been applied to sta- displacement-hull vehicle. that skin friction is the domi- bilize a laminar boundary layer. In this Hull speed is proportional to theGivennant source of drag operating on approach fluid in the boundary layer is square root of the waterline length ofa shell at racing speed, a substantialcontinuously "suckea' into the boat aOETJ human-powered watercrartreduction in drag is possible if skinthrough pores or small slots in the trve lông displacement hulls arefriction can be reduced. Skin frictionhull surface. Shells could make use of therefore less hindered by wave dragarises from a thin layer of water,boundary-layer suction if the' \vere than boats that have short hulls withknown as the boundary layer, thatoutfitted with a porous hull that would the same overall buoyancy. On theflows past the boats hull. There areallow water to seep in slowly. A small other hand, for a given buoyancy long,two fundamental types of boundarypump would serve to bail the water slender hulls have more wetted surfacelayer: laminar, in whiu-h the flow is out occasionally. area than short, wide hulls. The great-smooth and steady. and turbulent, in The texture of the vveteed hull sur- face can also plaa role in the re- LIFT duction of skin-friction drag. In'.es- tinations under the ausoices oTThe ro naics and S p ace DRAG ministration have sno\vn that a slick waxed surface does not always result in minimal skmn-rrtctiondrag. Sur- races with very tine grooves running in the flow direction, called riblets, have shown 6 percentlOSScrag than sn surfaces. iblets have been tested on rowed !/ shells by a group from the Flight Re- search Institute headed by Douglas a LHT McLean of the Boeing Company. The eroup covered a single-person shell THLST with an experimental plastic skin in (j which grooves been formed. The spacingbutween thegrooves was three-thousandths of an inch (about 80 FOUR BASIC FORCES must tre c isdared in designing boats such as the racing shell microntetersr.er than the groose shown her's: wei2ht, lilt, thrust and drag. \Vaiu!rt is the gravitational force acting on the sPacing on phonograph records. Tests bo:it and rho operator. Lift is ziormurllv generated by buoyancy. tit's upward force eguai toinhcateti rhnt the shell's maximum drew cigar othe water displaced by t:,e hout'hell. Additional lift, called dynamic lilt,speed was incrcisea b2 percent. A!- car: be productd by the flow of water urrdtr the hell. Thrust. in thcase of human- though this ma. eeni like an irsignifi- powcr'sd water vehicles, is the force produced by the actions of the operator (herosen rowinu) that propels 'she craft forward. Drag is the resistance to the boat's forrvard mo-cunt amount, ita.:uis :tlent to a four- tier: it aric.s in n:os rcraft frrri the arcuiton of a wake (wave dm2) and the friction boat-lengta ndvnr.tage over a tnndur tot seen the hshi and the water tlowirrg past it (skin-friction drag). \\ hen a hoar : as a 2,',)ii).jniu' rae-c. constantpe'sd. lift balances weight and drrusr balances drug. TIre key objective in boat Ott the emisi's cf such encouraing d'sin ito minimize drag at the normal operating speed of the boar. At th's speeds reces' suIts thu cxr:e:n',catal skin up- sarv tOt corr.peririve rowing. dr::ga minimized by making a shell light. lung an'l narrow. pried to the -u;i o: the U.S. Olympic
110
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EECN PC;NT FC.FLYLI:O FS:-1 2 0 0 5 tO 15 20 .1 .2 .5 1 2 5 :0 SPEED (:
cc.\ .trc.i to s rcw'cr :es ;;rcv frvt tha: three n:si1ier :.. .t ..c;\: .h rt caiatTiu.'.I rn cli:.:.ir 'LLdShulk ..ith he ':rtc :e.t:l bar''. ares. 'O '(''flJ t4..,.fl'C ovet rots exertion lane for six if a nd air. :'tl;s:ei:g prob. n all. itO'.\ Cs er, thee:: tpuf is ui:'..lcr'atCi ':11 could bc sob.ci H: . 10 I!:Ci .K.:r:ci :'cl: :e.-sc:.tlno tore than htdf .her'c- overarcr'ithe':11--it :c dv'.tee.'iLl'.as Vrios l.tON ..:eet asibrnerinv. u;t iCIS. : lever Cf :adstcticn.fiCi tdno :Thnz rIte.srrerntr.cu ' cre the 1 bc enough :e encice ln:vrLlly. y;teigi-.t. redul-eran'\ 'enni'..n.i a ridedisiriae.;s :a iuch more s. ,;tar tad ."ffl1iifl easulti-tele.:i.:il fO_ s:cni ccnuttton end .ie:crn-in;to1 has more .urf.;v sea than ut hull thun CIS :It tic turn n the cettur:..ur.t-cf toe C\ vist. lhe traditivnai i-ospa -ocred propr-nrt'.'en Los\.ctc provhlv iust anou::hs bus ancto Sn:;- :t:c't:Cn. in which the ro.s ci si:s stiil port a aersons veigot. Altltoi:gh itis a tact beingevelopc.i forreetcal a::dbrings into play onihe in tisClcs not optimal for human-powered irans- ransport:tOn p.::roses. Such propel- of his back. shoulders an: arms. er-driven bo is aroved :o a pot t near the surface of the a titer. a eonilcrablv less poss er :.'' the cv- hnmen.ro.'. ered submarine could Icea 15:cr and luss :frinzthan canoes orchat motion. The addition cf the slid-great improvement oser a skin diver o: boats. In the1 SOcs a three-rider Inc selt. ho; CS erncreases the p055 er 'a ith fipc:-s. In the earls 1950k a tao- oelier-dr'.ca catar.t.raa t'.vn- :a level of rowing to rivalhat of cv- personhiman-os eredsubmarine tu1ed boat) " as sao:t to he 1 chatat least for periods of more than eat faster than 5 three-oarsmen shell called the lsltn-Sub. designed by Cal- a fe-v minutes. (The shcrt-period ad-vin Gci:gsver. 'a-as produced in limit- ver a 103-kilometer course on theviatage of cycling is lost .sf:er about aed quantities b Pames River the .'\eroet-Genera1 minute because of the limitations in-Corporition. Pushed forward byta in Some LSCJ\IfltCSCS Or prorellers osed by the human circulatory and tre that the' can be fouled wth weeds h0-nsil1imetei- counterrotatincpro. respiratory s StemS.) peilers. the sluni-Su'o reportcdlv could tad can strke bottom a shailcw The inherent advantace of :eddal- cr hut otherwse achieve speeds of seven knotsabout roocflers are par- ivea-propellerboats ocr rowedthree ames the speed at which a di'.er h '-'-p--ieje-bo,ns therefore lies che:is in the fact can ssvim under.vater. dications {see -Th. Screw Propeller. that cars are a less efficient meeha- Other designs seek to red uce the sec w E. Eugene Larrabee; SC:ENTIFtCnisn'. fr channeling human energy to ond m;jor dreg component, skin-fric- \\tERICAY. Juts. 1980]. Sr-hlad:Xthe propulsion of the Lear. F;:rther- i. tion drag, by employing dynamic lift ieh-efieciev propeller desiensmore. a rowed boats une'. en speed cx- to rause part of the boat out of the sva- an he applied. s:nce the po\ver level :s more of a drag penehthan the icr and thereby reduce the boatk vet- citelo'v.In aeit:on. rroL'eilcr-tDsmooth. coatintious seed that can beted surface area. Although dynamic aecds are low enough so that cavtC- achiei ci with a rroPe 11cr. ion is not a preblem. tCavita::on. th lift does incur a drag penalty of its own, in many instances the reduction ormation of bubbles of v:ater vapor. esisners of fast hum n-po.\ cred in skin-friction drag more than cons- rises 'vhen the absolute pressure on ss atercraft has e also at:ernued to nensetes for the drag generated as a ome part of the :otatmg propeller s mamjze drag in novel s Os. One '.vav by-prod ict of the dvn antic lift. educed below the waters vaoor pres- to virtually eliminate wave drag and at Human-powered water vehicles that Ire:itreduces etcieacv and cantne same time reducesktn-trtctton take advantage of the dynamic lift ause excessis e ::ear on :he blade sur-drag is to submerge the hull: the orera- Sces.) Several rte.v human-posvered achieved by alaning are still in the tor ,vould have to he supaorted aboveimagination of designers, but anoth- etercraft have been outfitted svith the water by narrow struts extendinger way to generate dynamic lift has ropellers whose efficiencies exceed upward from the hull. The minimal- 0 percent. been arplied successfully: 1-ydrofoils. drag hull inthis caseisteardrop- I-[ydrofoils are underwater '.vings that The rotating motion of proaellersshaped, with a length between three so makes it relatively easy to drive produce lift in the same was' as air- and four times its width. plane wings prod uce lift. The required tern by an arrangement of pedals, Such a configuration is like that ofa size of a hydrofoil '.ving is quite mod- rockets and chains much like that of unicu dc. and balancing would like- cycles. SUCh an arrangement takes est compared with airplane wings. 'vise he difficult, if not impossthle, forFor example, at a speed of nine knots Ivantage of the rapid and strongthe rider. Theodore Schmidt alleviated ovements of the legs. The circular something under a tenth of a square this problem somewhat by attaching meter of foil area is needed to produce :daling action in bicycling remainsfour small outrigger h drofoils toan e most efficient practical method of enough lift to support a single rider experimental submerged-hull craft of above the water.. hydrofoil designed Llnsferring continuous power from his own design. A tricvclelike arrange- to produce the same lift at twice the human being to a machine. (Itis ment of three smaller submerged-speed would require only a fourth as tt coincidence that record-setting hu- buoyancy hulls would be stabler butmuch area. an-powered air and land vehicles de-riot as efficient. Since the ratio of stir- ad on a bicvcleiike drive train.) ,\lthouah the small wetted area of Ii face area to displacement gets smeller hydrofoil.vincsresultsin minimal ;\ champion cs clist can produce as disalacenient :ncreases. one rig hull skin-friction drao. Isydrofoils do incur a ut:rfereat type of drag.....the h dro- foil tra'.els tlsrouzh she '.vater it leaves heltind a vortex wake, iust iS arplane \1.NPO\VERED ',VfERCRA1"T dkpIa-csuortcd shapes.COilStrUclI(i,rivri:ils'sings ia The enersis expended in i propuLsion de'iccs. Rcttively primitive craft.sre pnled 'zc) or paddted (d. and mdc of sitch di' erue narcr1 materialsas rcrds, 'ood and miittI kin.tnre rolerncrating :he ' ortex wake iS manulcsteu it are madc of 'jod or metal andnrc rowed (. :iri.ltion that cults Pr Ic ;sef the as a drag callc.l induced ulrag. .\lso. is. sboildrrnd hccL-. or are paddled cit h fc.;t pc dais. britigimn. iito p Li the nr'ii'f the spray kicl.si;:p bvthe'.crtmcai muscles (v).Pcriul.drtveim- pro pet icr boats I 111%e ureater prop:Iim ti :1;- trls c.iml'l'C'rt:mS -ic hs ;lrofoil us '.he ihan ritt;_r ro;' ho;mts orajufe-.' tL'Ot huatS. '.m ci desi'is aid tulsa ts lava alcocut tlsru:eit mite .ri,ce if jhsitet back ott the such :rufr oumc'uumter. TIe wtared i:]!f fte..Cra tft;:tmjt suns in altl:caJ drag - :Lti;:IL:Itul c-alt j. for;m'ancc-. c;fecttic:i jnnatLthe pr&lmtt:n .t'arc .\ruc'.l'er:ss::crp.rol:iern's ;th hit-
.,...! ni-ri.' h.i.t-co:.:u It s la:vem toil enougi i:csip:. j;iC.lz :ui:-eeolJ ntcU.lk:.cdalc-d I to 1..aLrehn:\ hi.tli'i- c:.::. the era: cualLi cip :ur:hc:. pce.h. a.forc tht\ .0 i'ta.e c:f.'' I a clisinuec of 2.,.I,)-r.te_ the inrer !.:l t ci :hc . tcrIi rdx aiirtutcs'1 cecouds. eclips- :ersei ..s cbv red acme ,.2. Reeai. se cf ic-: :hc .; c':-lri recr.l tot1si:tCe mcv Cr It.roftis proeucc zcroft at the irthot:ent i!hcidi:s IsSC'CitucL3 by ii scconds. lhc tit.tts. efcourse. o 'cccJ. .otcrsOi t\ droro:!s. haunt- on cr-ru h'. are net dircrilv con:r.rtblc. becaie tuisa dtspcc;rtaz ha!1.i :-e. :roctl emit -ro not hu'.c thL'5iC ihcro'. inc record.' as set front a I!C'.I :cr the jflittCl tout pilses cn:e.i iroteniluls ItI!mn-,o.s e:u tnt-Stait tag start. a tzt. A wit !c.ted for a1- t:a:cs. '.vhich tta\itucl.i.ed spceds of Fish I has a high-c:heiacv. tspeed may ha'c:o he movtr.e ate me tItan knots. ouhe valet at I U knots before tt pcda-uriven propeller ndIno slender wmt-.cs supcc'rtcdb'.narrow vertical cneretcotigh lift :o support the Th:tl receaLly all h"an-pc.. ercd struts. The main '. tao, which carries ft and rider. This .soced ai\ cii he ':atcr-spred records vere held by 90 rcrccat of the craftsv ssih!e to achieve wh:c the craft is eioht, has a c:nacemcnt boats propelled h'; ours.tar \vmngspttn (1.8 meters) to mini- 1 snreortcd on thev.ater by its\\ium the intent of exceedinc these nine meat hull .:roer hdrofoii mizc mnducea crag and a smati chord, s:s, two of zis (Brooks and Abbott)or. no could reduce the ;ekcotf speed. :dth, to reduce sk:n-Irtctton drag. I 'S4 desioned and builtFim:ng Fish Th smaller front wing hasa configu- the drag caused by the increasedI. the first hydrofoilapabie of sus- ration much like an inverted T and face area would not chow the crafttamed flight on human power alone. is co as fast. tightly loaded: its mainpurpose is to The tickv problem of initially cettingprovmde stability and control. To this Stecking hvdrofoils o that smallerthe craft up to takeotT speed. whichend itis fizzed with a small, spatula- Is are placed beiO\V larger ones. as is had lagued earlier designers. '.'. as by- shaped device that automaticallycon- tie on motorized h' drcfc:lesseis. passed initially by eliminating the need trols the depth of the wino. The device ght C ire ant vent the ::oa lem.A emIt for a displacement hull. Flying speed :h such a tapered skates ot em the water surface, continu- Izader' arrange- was attained by catacuit:ng the craftously adjustino a thtn flap (analogous at of hvdrofoils could take oif atm::t'D the .vater from a floating ramp. v to the elevator on an airplane tail) to speed on the large upper foils.ay_ch as jets are launched front air- '.vhich it is !iakcd. ce sn:ctent st'ced has beenat- era:: carriers. lsing thtstiumag start" The front nine strut do uimiesas ned so that the lift produced by the L.nctag method. C) clist Ste' e Heug. a rudder and is connected to hicz dc
'"C /j\1 /1 Ii iillli-i)''j,I :1.' 1 :ie'.tI-i.:tcd.u;tJ .it-'(liS'ri tt CuriLit .rriti ,u.Ur.rt :r.nt -.r tI,L;uJ lb.(.L:tt. lELtt uitrlt'.'"L'Chruke.fiee'I run a st:iTtlt_ ii:. .Lttiit cçd b% 1 :il-Iri.ul,ii.ir-:!11cic:.iV; j.ii,.r. t:iCS ,ii 's';iet tiletivdrt'jiS"tivts euirtic,tkd .:lt,lll.iiiiuliy i.:..t..f eb,t tu..i.. Its iY i d 113 - . .. : . -.---- ...------,----. - - :ctrs br :un:.nccr'.ft i :...ien much a '.vc.cd ruict rue- ui: cle.1 ne ttat ;.:'j '- C the v:- ;.fltuet. a j :uOJ:e(t Ok'. cL .s,s-'t _I c../ r;':,:' 1,..':ii d Joped aa t-tzr .--,:) :encrnent ol'th.,rirstcrsort of our /1 craft.\'.'e:tLd 1gh:. eiaht pon- :oon floats tot: the hare :ttt an an- s;:;' :s,ited tukeo:T e aId Lu.' m.d-e t'ra:u a ' .. l_\i;i s:anistill. This proved to be possible, -LL'i.± .'II.Iu. \' and with practce acceleration from a -. stnadint start to the fuhv foil-borne r -., I mode took onithree seconds. The t:_--:- - craft ako became much more prac- I tical because it could now "land" on, as well as take off from. its floats. (The catapult-launched Fi,ing F1s: I I,.:-*.'_____.--.ttt: \__ gave the rider a dunking whenever he stopped pedaling.) Aboard the F!fitg Ffsh If one of us (Abbott) recorded a time of six min- utes 39.44 seconds over a 2000-meter Ifvoujt your advertisinto reach industry and course from a standing startabout 10 government leaders in Iral\ reach for SCIENTIEIC seconds faster than the single-person AMERICAY's Italian edition, LE SCIEYZE. rowing-shell record. From afling start the hydrofoil watercrafr also was TodaItaly represents a country dat has mastered the able to sprint 250 meters in SS.46 sec- tinest points of high technology across the 1il1 spectrum of onds, reaching a maximum speed of industries. The people responsible tor Italvs achievements anproximately lknots. on the tcchhology front arc reading LE SCIENZE. time is ripe for a technoloical If von \\ant to reach Tons' Severn for derails, conta: Therevolution in human-powered rec- LE SC1ENZE S.p.A. reational watereraft. Laser In:erna- tional has just tntroduccd the da1lard, Via Del Lauro. 14 a partially enclosed. seaworthy boat 20121 \idano. Italy designed by Garr'. Ho Several new Telerthone (011) 392-S05-894 pedaled catamaruns and proas (boats that have one main hull and a small- er stabilizing outrieser) otTer rough- '.vater seaworthiness and impressive PAID CIRCULATION: 80.000 AGE: speed. Jon Knapp of Saber Craft has ADS Audited 25-34 ) )O. designed and built a oropeller-driven 35-54 63% proa that is faster than a shell in rough ADVERTISING RATES: water but, unlike a shell, requires no 00 14% special skills to operate. The Dorvcv- Blaektvhite page 82,050 dc, a propeller-driven single-hulled Four;'color page S3,650 craft designed by Philip Thiel, pro- vides good load-carrying capacity at 86% University dcrce or cc1uivalcnt speeds twice that of the rowed dory 5 S % Ovns 2 + cars from which it was dertved. \Vhether or not hydrofoil craft be- 8% 0vn computer terminal at home come popular for recreation, there 11% 1 ± air trips outside \V Europe in last seems to be little doubt that they will 12 monrhs flgure prominently in the next round 26% Uses credit cards of breaking records. The international Human Powered Vehicle Association 1Z'1) Uses intl. hotels alwavs!frcqucndv encourages competitioninhuman- po'.vered vehicleson land, on sea and INVOLXTI) IN CORPOR.XFE PURCHASE OF: in the airwithoe: :inv arbitrary Itmits 3"% (;Ofli')UtCt' F-iardwarc placed on their design. Such competi- tion will push the SPCS. of human- 23', .omtutcr Sotr\varc Services no's ered h\ drofii craft c' higher. It 42 Scientiric Instrmerrs is not farfetched to en-. i:on such craft 9° Pritarc Ra'.\ l areriak Chemicals reaching speeds as high as() i.:nots_ one and a half :imcs fast us the f)Y i(i: ll-.s 3. itt4 speeds ttLitned 1:.T'it'm' I! and sia:ñca',tlfaster titan 'he:ecds at- taincd by cme sl:chs uc:erec h thletcc carmert.