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Journal of the

Amateur Yacht Research Society

Editorial TeamSimon Fishwick

Tom BlevinsDave Culp

Sheila Fishwick

AerodynamicsTom Speer

ElectronicsDavid JollyHuman & Solar PowerTheo Schmidt

HydrofoilsGeorge ChapmanInstrumentationJoddy ChapmanIceboats & LandyachtsBob Dill

KitesDave CulpMultihullsDick Newick

Speed TrialsBob DownhillSteam PowerLord Strathcona

StructuresKeith BurgessWindmills & TurbinesJim Wilkinson

Catalyst is a quarterly journal of yacht research,design, and technology published by the

Amateur Yacht Research Society, (RegdOffice9 Lynton Road, Thorpe Bay , Essex SS13BE, UK)Opinions expressed are the authors, and not thoseof AYRS. AYRS also publishes related booklets.

Contributions are welcome from all. Email themto Catalyst@fishwick.demon.co.uk, or send (atyour risk) disks or typed copy with illustrationsto the Societys office. AYRS can take noresponsibility for loss or damage.

AYRS members receive both Catalyst and thebooklets. Subscription is UK20 or US$30 perannum for a Full Member, 10 or $15 forstudents and retired members. Send subs-cription requests and all other queries to theAYRS Office, BCM AYRS, London WC1N 3XXUK, phone +44 1727 862268 or email:ayrs@fishwick.demon.co.uk

AYRS is an UK Registered Educational CharityNo 234081 for the furthering of yacht science.

Website: http://www.ayrs.org

2000 Amateur Yacht Research SocietyBCM AYRS, London WC1N 3XX, UK

All Rights Reserved

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Sir Reginald Bennett was best known to the general public as a British Member of Parliament,and the man who as Chairman of its Catering Sub-Committee filled its cellars with fine wines,but to the yachting world he is better known as firstly Chairman of AYRS and then of theWSSRC.

He was born in July of 1911,in Sheffield, England, the sonof a civil servant. He won ascholarship to Winchester

School, where he started theschool sailing club, and anotherto Oxford University where heread physiology. He thencontinued his studies inLondon first in medicine thenspecialising in psychiatry.

He had always had a love ofyachting. At Oxford, he sailedfor the University from 1931

to 1934, and in 1934-5 washelmsman and navigator onthe J-Class Shamrock V, racingagainst the Americans for SirRichard Fairey. In 1936, hewas reserve for the BritishOlympic yachting team at Keil,and later raced in the 12 Metreyacht Evaine. He was founderof the Imperial Poona Yacht

Club, an institution whichdespite its name is peculiarlyBritish, devoted to the lighterand enjoyable things of life.For example, each year itchallenges the OxfordUniversity Sailing Club to abackwards-sailing race on theRiver Thames!

He learned to fly before thewar, and gained his wings withthe British Fleet Air Arm in1941, serving as a flying

medical officer with the rankof Surgeon Lieutenant-Commander (RNVR). He wastorpedoed twice, and awardedthe Voluntary ReserveDecoration in 1944.

He was elected Member ofParliament for Gosport &Fareham in 1950, remained sountil his retirement in 1979. A

master of fine wines, he won anumber of wine-tastingcompetitions, and claimedafter his retirement to havemade the best use of theParliament cellars since GuyFawkes filled then withgunpowder in an attempt toblow up the building (and themembers) in 1605!

Reggie Bennett becameChairman of the AYRS in1972, succeeding Sir PeregrineHenniker-Heaton, and serveduntil 1990. During his timehe built up a strong support forthe Society. He was a yachtingfriend of Prince Philip, Duke

of Edinburgh, and persuadedhim to become our President.In 1980, he succeeded BeecherMoore as Chairman of the RYA

Speed Sailing Committee, andwhen that body wastransformed into the WorldSpeed Sailing recordsCommittee, became its firstChairman, continuing untilshortly before his death. Underhis patient leadership, theWSSRC has becomeuniversally recognised as theauthoritative body for thesupervision and ratification ofrecords under sail.

He is survived by his wife,four children andgrandchildren, to whom AYRSextends sincere condolences.

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The AYRSs longstandingmember John Hogg died on 24thJuly 2000 at the age of 85.

John was born soon after thestart of the Great War on March19th 1915 in the seaside village ofSketty, near Swansea, close to thehome of his mothers talentedCavill family.

After the Armistice his fatherreturned to the iron and steelindustry and the family movednorth.Although the family sufferedmuch from the effects of theDepression on employment in

steel making, John received anexcellent education at theManchester Grammar School.This led him into his lifetimemanagement career with the GasIndustry as a chartered engineer.

In the early 1950s, John hadmoved South to manage the newlynationalised Southern Gas Boardin Bournemouth and, of course, tomess about in boats of everydescription. By this time he was

already a radio control pioneer,developing most of the radio andelectromechanical systems for asuccession of model yachts whichhe raced successfully in Poole.

This led inevitably to his workon yacht research, testing scalemodels of Americas Cup challengersSceptre, and Kurrewa and designingand building new ways of measuringsailing performance at full size. Aswell as providing endless fun on

other peoples boats, he found thisa perfect outlet for hisextraordinary inventive skills.

Soon he was creatingmicroelectronic forerunners oftodays instruments for measuringwind and water speed, aerofoilshape, boat speed to windward(Vmg), and countless othergadgets which his embarrassedchildren would be expected to teston roads and various other public

places.

John Hogg, 19th March 1915 - 24th July 2000

Working with good friends[George Chapman and others], hispapers on performance measurementprovided an important practicalcontribution to the creation of theAmateur Yacht Research Societyand its influence on fast yachtdesign.

In 1960, when his job moved toSouthampton, the family moved

to Curdridge. It was here that Johnand Ena settled happily in the yearleading up to his retirement. Onlythen was he persuaded to buy anextremely small yacht of his own.Moored on the Hamble, theEmily Rose was frequently trailedto St Mawes for their annualholiday and on it he enjoyed manyhappy summers with his grandchildren, Derek Mallinson andother Curdridge friends.

In 1970, sailing had started tobecome an industry, and Johnsson Rodney was able to applysome of this home backgroundwhen he joined the small businessthat has developed into rope-holding equipment specialists,Spinlock Ltd. Cowes.

John was the first to acknowledgethat his rich and varied life wasonly made possible by Enasendless patience and devotion. As

wife, mother, crew, cook,

housekeeper, secretary, she wasalways the supporting audiencethat he needed. So when the time

came, and illness forced her toslow down, he relished theopportunity to care for her for aslong as he was able.

It was from the strength of theirlife together in Curdridge thatJohn so enjoyed being able tocombine his fascination withresearching, measuring andmaking things with his abidinglove for the village and its people.

I met him in 1947 shortly after

he had helped form the RadioControlled Models Society. Thosewere the days of one-valve receiversworking a sensitive relay which inturn controlled electro-mechanicaldevices, in which he employedmuch ingenuity. He was on totransistors as soon as they came onthe market, and led their use.

Equally, and for the AYRS moreimportant, he was a leader insailing boat performance

measurement, using pocket-moneybudgets and largely home-madeequipment. Looking back it isremarkable that he was involvedwith Americas Cup challengers,but times have changed ! Evenwhen affordable yacht performanceinstruments came on the marketin the late 1950s, the cost of a fulloutfit equalled what he (or I) wasprepared to spend on the boat.This is still largely true, but then it

is difficult to compete financiallywith sponsored professionals.Only in very recent years has theprice of dinghy-scale equipmentstarted to come down.

His writings in AYRS publicationsrank with those of, for example,Edmond Bruce and Harry Morss,and are a lasting memorial.

He was a good friend who willbe sorely missed.

G.C.Chapman

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We had a good uptake inpeople attending, in fact 31of uspartook of the dinner and thesocial evening on Saturday eveningwhere innovators discussed andshowed videos of their ideas, someof these still being models.Speakers included SimonSanderson who will be making anattempt at breaking the Worldspeed record in "Bootiful", a 50'

catamaran with innovative steeringcurrently awaiting favourable windconditions.

There was Chris Evans fromGermany discussing his foiled 20'Trimaran and Peter Rhodes-Dimmer discussing his currentRoyal Canoe Club Class B SailingCanoe project, a 17' hull poweredby a Boatek wing asymmetric foil.Kim Fisher showed us a model ofa concept he has in mind for a

water-borne sailing vessel usingland yacht principles withflotation wheels instead of hulls.Bob Downhill stood up and said afew words. He had been invitedand had kindly agreed to attendthe event and to be responsibletogether with Norman Phillips torun the timing for the speedcourse using his own sophisticatedequipment including laser tapemeasurement.

Among the models demon-strated on the water were:A sophisticated Hapa lateral

resister/stabiliser by John PerryAn wind-controlled symmetric

foil sail on a 6' radio-controlledmodel showing its paces andcontrol worked convincingly byPeter Worsley.

An 18" windmill poweredmodel proved its ability to godirectly into the wind (believed by

some to be a breach of the Laws ofThermodynamics) but proved infact that this certainly is notbogus. To go against the windusing windmill power is possible!again by Peter Worsley.

Other models not actually onthe water were scattered about thelawns in front of the club andbeing thoroughly discussed by thedesigners.

Among the man-carrying boatsnot on the speed run was TorixBennett who unfortunately couldonly be with us for a half day onFriday with his tri-scaph Mini-Sea Spider but he quicklylaunched and demonstrated itsimpressive ability.

A 10' pram dinghy with an oldversion of the Boatek asymmetricfoil sail was available for anyone tohave a go at and had a good take

up of enthusiastic volunteers.Winds in general varied

between 19 and 7 on Saturday and15 and 6 on Sunday. Top speedsmeasured over a 500m coursewere:

SaturdayPhilip Middleton with Triton

Chariot, a 20' foiled trimaranachieved 13.32 knots, wind speedratio 0.86

Patrick Mayne with Speedbirda 21' long Bruce foil stabilisedmonohull achieved 11.09 knots,wind speed ratio 1.39.

Simon Fishwick with his 16'open sailing canoe achieved 4.70

knots, wind speed ratio 0.38.

SundayDanny Mann/Philip Middleton

took over Triton Chariotachieving17.39 knots, wind speed ratio 1.24.

A National 12, (helmsman'sname not known) achieved 7.77knots, wind speed ratio 0.60.

Chris Evans with Trixi, anaerorig trimaran achieved 7.19knots, wind speed ratio 0.48

(before he broke his mast)Slade Penoyre with an early

Catapult inflatable catamaranachieved 7.18 knots, wind speedratio 0.80.

Winds of Change: A Rally for innovative water craft

We had great weather for our first "Winds of Change" Rally which took place on August 18th20th, at the Royal Harwich Yacht Club, on the estuary of the Ricver Orwell in Essex, E. England.

John Perry towing his hapa

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Tritons ChariotSimon Fishwicks canoe crept

up to 4.97 knots, wind speed ratio0.41.

Many thanks to the Commodore,the sailing committee and membersof the Royal Harwich Yacht Clubfor not only allowing but alsoactively helping to make this asuccessful event. Special mentionmust go to Herbert the driver ofthe committee boat which was

used for stake boat No 1, andTerry Corner, vice commodore,skipper of his own 30' Freedomrig yacht being stake boat No 2.

Lots of others to thank! ChrisEvans, co-sponsor of the eventdonated champagne and wine forthe individual events. Linda &Denis Alan, with their motor boatand C & D Rowe, with their 14'hydrofoil stabilised craft, standingby as safety boats, Steven Fryer

who brought his motor cat fishingboat around from Felixstowe Ferryto act as support boat on thecourse. Sheila Fishwick who splither time between manning theshore based headquarters andspending time on the stake boats.In fact all those who made theevent go with a swing.

Bob Quinton5 knots or bust - the Editor at

Winds of Change!

Monohull 24 hour recordnow 430.7 miles!

Dominique Wavre, skipper of18m (60ft)Vende Globe entryUnion Bancaire Prive, has claimedthe records for the maximumdistance sailed by a singlehandedmonohull in 24 hours with adistance of 430.7 nautical milesbetween December 8 at 17:00

UTC and 9 December at 17:00UTC an average of 17.95 knots.Sailing at speeds of up to 30

knots at times, the Swiss registeredUnion Bancaire Prive set therecord between 45 45 21S, 1122E and 4522S, 21 37E on itsway round the tip of Africa intothe Southern Ocean.

With the arrival of this goodnews, the delighted skippercommented: It is super to

baptize my entry in the IndianOcean with this record. I wasalready a few years ago holder ofthe record as a crew with IntrumJusticia during the Whitbread with427 miles; but that was setapproximately 1000 miles more tothe east from here, and we were 12on board under spinnaker!

It is a little mad to be goingfaster with a shorter boat andsinglehanded! These boats arefabulous and especially Union

Bancaire Privewhich is a truewind-rocket. It is stressful, theboat vibrates a lot, like a sailboardand it all becomes difficult onboard. One really is very shaken

and I have even got a little fed up!But I am super content with theway were going.

With bursts of speed to 32knots, the skipper thought well ofbeing close to dethroning YvesParlier of his record establishedlast December (420,06 traversedmiles). Marc Thiercelin, hispredecessor, had two years oldearlier made 396,5 miles duringone of the stages of Around Alone.

At the time of writing, UBPand the rest of the Vende Globefleet are crossing the SouthernIndian Ocean towards the south ofAustralia. According to theforecast weather, the situationwhich awaits us in the south ofAustralia is delicate. There is adepression which discourages usfrom leaving the course for CapeLeeuwin but an enormousanticyclonic ridge which bars the

pathunder Australia. The weatheris not too cold, they are quitelenient conditions for the latitude50s.

Information from WSSRCand Wavres website -

www.dominiquewavre.com -Translation: S Fishwick

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Your Letters

A Rope Experiment

Im all for simplicity, butsuspect that Im not the onlyreader who finds Franks report[Catalyst 2, p52]just a bit tooingenuous. Surely hes usedYoungs Modulus where heshould be speaking of spring rate- and the distinction is not trivial!

But nonetheless, I do agree thatrope manufactureres are remarkablycoy about giving proper engineeringspecifications for their products,

and that textbook practice hasfailed to keep up with the arrivalof MMFR (man-made-fibre rope).For instance, in an article in anAYRS publication a few yearsback, I argued that in manycircumstances an anchor warp ofMMFR offers more safety for agiven mass than does the all-chainwarp commonly employed. Onthe other hand, few sailing bookstell us, for instance, that a reef

knot in conventional 3-strandman-made fibre rope is morethan commonly useless - in factdownright dangerous. Why do theauthors of such books leave us tofind out the hard way?

And more generally, I feelFranks letter should encourage usto put more emphasis on sailingsafely and less on sailing fast.The latter may be more glamourous,but I suspect more sailors lose

their lives through mis-use of ropesand bad seamanship generally thanthrough a misunderstanding of fluidmechanics. Further, as Frank hasshown, you dont need a lot ofexpensive kit to do the research.

Mike Bedwellmichael_bedwell@hotmail.com

Determining MaximumBoat Speeds inRadiosailing:

The question of what R/Csailboat is fastest, has been hotlydebated in the past and has been aperennial focus of spirited debateever since two or more modelyachts hit the water. The followingis an example that will require thecooperation of anyone that has aconstructive idea or ideas on howto improve upon this draft. Anyand all of your creativeexperiential inputs will be mostappreciated.

In order for order to be createdfrom a potentially chaotic set ofrules, it has been decided tocategorize all of the recognizeddivisions in Radiosailing into threemajor Classes.

Class 1: All recognized One-Design Classes in the AMYA orany National RadiosailingAuthority recognized by ISAF-RSD, regardless of LOA. This isinclusive to multihull; multimasts

and all boats will compete onlyagainst other boats in its specificclass. As a result of the theoreticalfact that "all one-design boats arecreated equal", the skipper will bethe holder of record in the Note ofRecord for that particular One-Design Class of yacht.

Class 2: All recognizedDevelopmental Classes in theAMYA or any NationalRadiosailing Authority Recognized

by ISAF-RSD regardless of LOA.This is inclusive to multihull;multimasts and all boats willcompete only against other boatsin its specific class. Skipper, designtype, manufacturer, and sail / rigdesigner, year of manufacture andany other detailed pertinentinformation should be included inthe Note of Record.

Class 3: UnlimitedExperimental Class: this will be

broken up into 2 major sub-divisions. Class 3/A will havemonohull yachts. Class 3/B willhave multihull yachts. Both ofthese in turn will be sub-divided

into three categories based onLOA; LOA/O over 1.5 Meters;LOA/M medial between 1.1 butnot greater than 1.5 meters; LOA/U 1 meter and under but not lessthen .70 meters. Sail area andnumbers of masts will not factorinto the unlimited experimentalclass. As the intention of this classis to go for all-out speed regardlessof hull forms and rigging types.But as per Class 2, Skipper, design

type, manufacturer, and sail / rigdesigner, year of manufacture andany other detailed pertinentinformation should be included inthe Note of Record.

An example of a Class 3/BLOA/O boat will be of a multihullyacht that is 1.9 meters LOA.

Rules for "cross-divisional"competition will need to beestablished in order for a spirit offairness to be at the forefront. It is

recommended that any cross-divisional competitions be keptunofficial in order to reduceredundancy. Redundancy in thiscontext is used as a means forclarification; as each division willalready have had its ownindividually set records with whichto have to compete against.

Course Standard Measurementswill be in the metric unit ofmeasurement with the English

Standard of measurement inparentisies. The length of theCourse will be of two types 2Long and 1 Short. The 2 LongCourses will measure either 25 or50 Meters (whichever is practical)with the Short Course measuring10 Meters. An exception to thiswill be in the special event that aSet Long Distance Course is calledfor. New Zealand s WellingtonModel Yacht Clubs Project "X"

from the South Island to North

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Island or from the ShakerVillage Sailing Clubs swimmingbuoy and across Lake Masscomato the Dartmouth Sailing Facilitysouter mooring fields buoy and

back, a distance of approximately3 kilometers (1.8 miles). Or anypermanently set distance ofapproximately 250 meters plus. Apermanently set course of between101 to 249 meters will beconsidered a Medium LongDistance Course. All speedattempts will be of the "Flying-Start" type. As some yachts arefaster going at a particular point ofsail then others, the point of sail

and course configuration will beset to met the unique requirementsof that particular yacht. A notedetermining the yachts point ofsail should be included. Forpractical reasons this latter courseshould be applied using the ShortCourse or the Medium 25-MeterCourse. However, a long distancebroad-reach might serve mostmultimasted / multihull sailingrigs best.

Please, note that this laststatement is NOT to beinterpreted as an inference foradvice, but that as of an exampleto help clarify the pointspreviously stated.

Verification Procedures will bedetermined by a committee of notless then 4 current members ingood standing with the relevantNational Sailing Authority andshould have no less then 2 neutral

committee members and 2 ormore but not more then 7members of the record attemptingyacht club(s). The sanctioning ofthese events will be done as for anyACCR or any other National orInternational event protocols.

Indoors Record Attempts: It isrecommended that the use ofhigh-velocity commercial gradefans be used for indoors recordattempts. A windmeter measuring

the wind speeds in meters per

second from 1 meter from thecenter of each fan used and at thestart, midpoint and finish lines berecorded. This will allow foraccurate assessments of the

conditions used for each attempt.Outdoor Record Attempts: The

variability of any outdoor attemptspresents a number of challenges, ifwave action, sea state, wind shiftsetceteras are counted in, anaccurate figure for each run will/should have a constantly variableout-come. In this event the highestspeed attained, will be theofficially recorded speed for theyacht.

Materials Needed for an officialrecording: A Radar Gun (two ifpossible), windmeter(s) to measurewind speeds from the center of thefans at 1 meter, start, mid andfinish lines. Stop watches/chronometers or any otherprecision timepieces (regularwatches are not recommended)time to be recorded to the 1,000of a second. Any other time /distance precision instrumentation

that you can suggest, will beconsidered for inclusion into thissection.

Information on all records andphotographs should be forwardedto the relevant Class Secretaries,the Presidents of the NationalRadiosailing Authorities, ISAF-RSD Officers, the Open ClassSecretary of the AMYA and will bekept in the files. Any informationwill be freely given upon request

and an answer returned via e-mailor if by snail mail the requestmust, please, be accompanied by astamped self-addressed envelope.

The premise of this endeavor isto keep accurate records on theevolution of our sport ofRadiosailing and not as a means ofestablishing "bragging rights" overone-another classes. With yourcooperation, we will have theopportunity to set the standards

for the following generations of

skippers, designers, manufacturersand constructors to build upon.

I hope that some of you willforgive me, if in sending you somee-mail messages or letters in

request of your counsel that itwont be misconstrued as beingintrusive on my part. Its just thatIll occasionally need to "pick-the-brains" of those of you whoseadvice Ive come to trust! Acommittee of Class Secretaries,AMYA Officers, ISAF-RSDOfficers, and as varied a group ofindividual Radiosailingenthusiasts, as possible will beassembled. Although, our world is

getting "smaller", the geographicdistances remain the same, so allcorrespondences will be handledeither via e-mail or snail-mail!

A form detailing the Note ofRecord is presently in the worksand will be submitted for yourcritique in the near future.

Thank you all in advance. Peaceand take care of yourselves.

Jose Torres Jr.Open Class Secretary

AMYAtorfam@valley.net

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The Amateur Yacht Research Society announces the establishment of a Prize to be awarded inmemory of John Hogg, the distinguished yachting researcher and amateur, who died this year onJuly 24th. The prize, of a value of 1000, will be awarded for the most meritorious contributionto innovation in yacht science made by an amateur researcher.

Nominations for the prize, which is open to anyone of any country, whether or not they aremembers of the Society, should be submitted to the Secretary of the Amateur Yacht ResearchSociety, BCM AYRS, London WC1N 3XX, to arrive by 1st September 2001. Nominationsshould be supported by evidence of the merit of the work done, peer review if any, details ofpublication (which may be in a recognised journal, or the Internet), and all other informationthat may be of use to the Prize Committee. If the work or any part thereof has been supported bygrants or other funds, full details should be given. Receipt of such funds will not in itself be a barto nomination, but since in part the purpose of the prize is to encourage work by amateurs, it isa consideration. Research carried out as part of normal employment will not normally be eligible.All information received as part of a nomination will be treated in confidence.

Award of the Prize will be adjudged by a Committee chaired by Mr. George Chapman, who is

himself distinguished by his contributions to sailing hydrofoils and marine instrumentation, anda long-time friend of John Hogg. The award will be announced at the London Boat Show,January 2002.

The Amateur Yacht Research Society acknowledges with gratitude the generosity of the Hoggfamily that has made the establishment of the AYRS John Hogg Memorial prize possible. JohnHoggs writings in AYRS publications rank with those of, for example, Edmond Bruce and HarryMorss, and are a lasting memorial.

He was a good friend to the Society who will be sorely missed.

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Possibly the best type of structural concept for maintaining the shape ismonocoque honeycomb cored sandwich construction using fibreglass face sheetsas complex shapes can be made relatively easily using fibreglass molds andvacuum bagging techniques.

Layups can be made which incorporate varying thickness skins to providereinforcing and basic strength where required while maintaining the outsideshape while the interior of the hull varies.

Assembly is in the manner of plastic model aeroplanes.The structure is broken down into easily manufactured components which

are then stuck together with glue.Below is an example of how this would all go together for a three segment assembly.Before we get to the manufacturing bit someone has to say how thick all the various parts have to be.You cannot make up a boat with all the skins the same thickness as the loads are never the same at any

two parts of the structure although that is a good place to start.John Perry built Crusader that way in his back garden and highly successful it was too. Crusader had

1600 sq ft of sail area was 52 feet long and some 25 feet wide and weighed 2.5 tons..I asked him where he got the design from and he told me it was a Tornado scaled up by a factor of 2.5

knowing John I believe him.He built it in his garden on Eel Pie Island

in 1977 from wooden false work from theinside out so the external f inish leftsomething to be desired.

The construction was foam fil ledsandwich about an inch thick with localreinforcing as required for the attachment ofstays etc and there was not a bulkhead anywhere.

In 15 knots of wind it did over 20 knots.I know because I measured it using acalibrated trailing log speedo.

Right then on to the nitty gritty.

In the quest for more speed of catamarans the only way to reduce drag is to make the hulls withas small a cross section as possible consistent with adequate buoyancy, structural strength, andstiffness. Buoyancy is easy to calculate, as is structural strength, but structural stiffness is not.

To state the obvious When designing long thin hulls it is essential to maintain the shape of thehull under all loading conditions.

O.K. where do we start?

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The loading cases for a boat are many and the combinations of load cases arealso many. The first load case that springs to mind is the boat sitting on the water.This produces up loads on the hulls equal to the weight of the boat.

With the sails set and moving forward side forces are applied to the hull (or thedagger boards) to equal the side force from the sails. The forward thrust causes a

pitching moment that shifts the centre of pressure of the water forward and henceputs more loading on the bows.

Another more interesting load case is the boat broaching at high speed in thetrough of a wave as the bow buries itself in the next wave causing the boat to yawcausing it to experience high side loads on the forward hulls.

You can (and should) go on like this building up primary load cases until youcannot think of any more.

Each of these primary load cases are completely balanced i.e. the boat is alwaysin equilibrium in all 6 degrees of freedom. For dynamic cases the mass and massmoments of inertia counteract some or indeed all of the unbalanced externallyapplied hydrodynamic and aerodynamic loads.

Knowing all the external applied loads the internal loading in the structure can

be obtained and the boat can be stressed to obtain the sizes of all the bits of structurethat contribute to the structural model of the boat.

This brings us up to the subject in the title long thin monocoque unbracedhollow structures subjected to side loads.

The basic formulae for calculating stresses assuming plane sections remain planeis: fm/y = M/I = E/R where fm= stress produced by the bending moment M

y = distance of the fibre from the neutral axisM = Moment applied to the section about the neutral axisI = Second moment of area of the section about the neutral axisE = Hooks modulus of elasticityR = Radius of curvature produced by the moment M

Also of course: fa = P/A wherefa = the stress produced by end load PP = the end load applied to the sectionA = the area of the section

And by inference: fs = S/A wherefs = the shear stress produced by shear load SS = the shear load applied to the sectionA = the area of the section

There are two axes about which bending takes place and the stresses have to be added to get the total stresses whenworking out the primary and combined loading cases.

Keeping it simple then lets go back to the original objective how to maintain the shape under load. The probability

is the cross section of a bow section is elliptical and a quick look at possible external loadings would reveal modes ofdeformation of the section caused by local loads.The next obvious investigation must be the effect of the accumulation of load on the overall structure. Finally the

effects of the overall loading deformation on the local deformation load has to be considered.About this point you are probably wondering what I am talking about but if you bear with me it all should become

clearer.

In the formulae for stress, the radius of curvature refers to the shape a beam takeswhen subjected to an applied moment. This moment produces stresses through thesection and the stresses when multiplied by the area of any particular section givesthe end load at that point in the structure. Because of the curvature of the sectionthe tension or compression in the skin of a thin section requires that a force W is

applied perpendicularly to the skin equal to faA / R or more regularly quoted as

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T/R where T is the end load in the skin.So if you look down on a long thin hull subjected to side load then the two

outside skins apply loads which tend to flatten the section. As the section flattensthe moment of inertia gets less , the stresses increase, the loads get higher andeventually the section flattens completely.

If you want to see this in action get a drinking straw and apply a bending momentat each end and watch the mode of failure.Naturally if there is already curvature built in during manufacture this modifies

the loading but the cross section of the hull must have bending stiffness to withstandthe crushing loads. Additionally if honeycomb construction is used the difference ofloading between the inner and outer skins must be chosen carefully such that thedifferential forces do not exceed the crushing strength of the core. If you have a thinoutside skin and a thick inner skin ostensibly carrying all the major bending of thehull, it is possible for the skin to come away from the core.

Naturally the radial stiffness of the cross section has to have no more than threethin sections or the ring stiffness is lost by the structure becoming a mechanismwhich will be unable to withstand any radial unbalanced loads.

Enlarging a bit on methods of assembly it is worth mentioning good and not sogood designs, bearing in mind the structural ramifications. The first example of across section is one with three seams longtitudinally which translates in structuralterms a frame having three pin joints. It is fairly obvious that this section will notcollapse.

The sandwich construction provides longtitudinal bending stiffness and if thejoints are not too thin then local deformation is not significant.

The same line of reasoning applies to a section with two joints to make up the hull.Where this type of construction is useful is the designer has a lot of freedom to

make the moulds for laying up the sandwich making sure there are no reentrant angleswhich would interfere with the vacuum bagging that is almost mandatory for makingthis type of structure.

Proceeding on the line of reasoning if the joints are made flexible or indeed in themore general case of an unsupported thin shell structure then it is not difficult tovisualise the various modes of failure that can occur.

The example shown here is reinforced top and bottom with thin shell sides. Waterpressure crushing loads would combine with structural overall loading to cause earlycatastrophic failure. Reinforced sides would encourage the thin shell to bow upwards anddownwards, which in turn would reduce the moment of inertia to a point where largecracks would appear where the thin shell was forced into a small radius of curvature.

People think that the process of design is checking the worst stressed areas and making sure those bits do notfail. Most boats are much too bulky and there is a built in safety factor which saves the reputations of the lessfamous designers. You know the sort of thing the first time the boat goes out the odd failure occurs here and therewith attachments of stays to hulls cleats and the like. However when you get to really cutting down the safety

margins you get into the realms of having to pay attention to every part of the structure.Compare the thicknesses of aeroplane fuselages and the average yacht. If the average passenger examined thestructure of a Boeing 737 stripped of the interior furnishings he or she would be appalled at what little held them30000 feet up in the air.

Interestingly enough if you use a computer program for calculating the stresses the resulting radial stiffnessrequirements indicate relatively high radial moments of inertia are needed which do not appear when you straingauge sections. When displacement of the cross section is taken into consideration the radial bending stiffnessrequired is of the order of 10 times less than the calculations show and effectively build in a safety factor thedesigner does not know about.

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Team Philips, as we now all know,came into difficulties on March 29th2000 during her sea trials when a45ft portion of the port hull becamedetached. She was towed back toTotnes, Devon and was taken to thebuild site so that repair work couldbegin.

A full structural survey showedthat the 45 ft port bow section ofTeam Philips failed due to aproduction problem. On each sideof each hull, and along most of theirlength, there were two longitudinalcarbon strakes (strips) which arepositioned to take the transverse andvertical load on the hulls. The surveyestablished that the strakes were notfully bonded to the Nomex

honeycomb core and therefore wereunable to take the compressive andtensile loads applied to them duringthe sea trials.

We have heard that although thehull was surveyed using ultrasonictesters prior to launch, thebubbles, effectively the whole

length of the strakes, were so largethat the equipment failed to detectthe edges.

The solution involved workinside and outside of the hulls. Theunbonded strakes were accessedfrom the outside of the hulls byremoving a 405 mm wide strip ofthe outer carbon skin and theunderlying Nomex core from oneend of the hull to the other. The new

What went wrong, and how Team Philipswas repaired

additional structure consisted of alongitudinal corrugation of carbon/foam core which provided a shearlink between the inside and outsidehull skins.

Additional longitudinal carbonstrake material was applied to theoutside face of the corrugations to

produce a relatively slender beamwith balanced sections. These strakesare subject to very high endloads,both tensile and compressive, as theyreact to the hydrodynamic loadsgenerated by the hulls as they passthrough waves.

To prevent buckling, a numberof lightweight ring frames werebonded every 0.6 metres to theinside of the hulls. These frameswere produced from 3D design

software, and were cut by water jetfrom sheet foam in segments. Thebasic laminate was completed in thefactory and the segments passed intothe boat through the deck hatchesfor assembly and final taping to theinner skin of the hull.

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FERRO-CEMENT REPORT

Since our previous articles on ferrocement construction there have been a number of changesso a brief update and account may be useful to someone considering purchase or even building aferrocement craft.

Most surveyors now refuse to report on ferro-cement hulls, and for this reason only third partyinsurance is available. Without either destroying orultrasound testing the entire hull, it is not possible to

say beyond doubt thatthere are no voids and sothey will not sign. If thehull was built andplastered under survey thisseems very unfair.

Blue Circle is my thirdferro yacht. She was givento me as a derelict, havingfallen over when one ofher legs broke, and shewas holed in the bilge.

Experts did not agree onthe best method of repair.The way I chose was fast, not expensive, and hasworked well for three years including rough weatheroffshore and drying out on my tidal mooring(without legs as its mud). Other methods may haveworked as well, but I worried about fresh cementbonding to the 1976 original.

I enlarged the hole to sound non-rusty rods andmesh then removed all loose cement. I straightenedthe bent rods and tied in extra where the old oneswere rusty. I replaced mesh with new wire. Then

complete and strong the strength is always in thearmature I mixed epoxy resin with ordinarycement powder and plastered over the sole, fitting awater intake in case a future owner should want awater cooled engine. The cement powder is only afiller but it makes the repair the same density as theoriginal, hit the hull with a hammer and you will notfind the repair (hence the caution by surveyors?).Frost has not caused any problem. Blue Circle is nowfor sale, finished.

Because of the lack of insurance, ferro cement yachtsare inexpensive. This should be a warning to everyone

not to build a new yacht in this material without some

exceptional reason buy second hand but be verycareful and decide in advance what you need.

My previous concrete boat was a 38' shell lyingin a quarry. I worked on it for a while but I could

not complete the job by thetime, in 1995, I had to sellto raise money to fight acourt case with my bank. In1999 that problem wasresolved, not by lawyers butby Robin Fautley FCA whoaudits the AYRS accounts.In the meantime, severalowners had also failed tomake further progress onthe hull, and it was again

for sale in January this year.(Can you call a concrete

structure, with rust and some 20 extra holes it?).Its condition was not good I have not seen thelast survey report but it certainly frightened the yardwhere it was stored, and neighbouring yacht owners,who all felt it was too dangerous to be moved especially by crane over their boats! In part it may bethat the yard stood to lose 10 per week and theneighbours would no longer have a chance to stealanything. She became mine on 1st February.

This second (fourth?) concrete boat (CB2) will

become Sea Bee II if I complete the work to gether seaworthy. Target for this is October. I have anengine, a Lister 20 h.p. with starting handle. I amabout to install 2 tons of ballast and have bought 40pigs iron ones weighing 56 lbs each. I hope mybrother is making a rudder and I think I have fixedthe keel. This hull seems to be built using pipesinstead of rods. Beside the flat steel keel plate a pipewas laid on each side. These, especially the port one,had rusted and the concrete around had beencrushed. The two worst areas were aft where the keelhas been in wet ground for 12 or more years, and

forward where the main support was probably not

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wide enough. I know that for long periods the hullwas full to the stern tube with rain water so veryheavy. Note: avoid hulls made with pipes if you can.I hope I have cured this by inserting a steel rod forreinforcing concrete right along the pipes from aft,

coating them with cement as they went in. I thenchipped off all the external rust and loose cementand applied a thick coat of epoxy and cement mix.When filled and faired, I plan to paint with epoxytar to the waterline. On Blue Circle this has beenvery satisfactory tar does show through the antifoulin places but its not a worry to me.

When ferro cement hulls are built, the mesh androd (or pipe) armature has to be suspended, so thatthe cement can be applied in one non-stop operationall over the hull. Adding this extra weight oftencauses the mesh to move. Port and starboard quarters

of CB2 are not the same shape. Mainly this is abovethe waterline, and as I can only see one side at atime, I shall not worry; but just maybe she(havingbecome a boat) will try to sail round in circles. Foamsandwich yachts are also sometimes different. This isdue to having a wood frame and heaters to bend thefoam or cure the glass. If the heat is not even (justhot sun on one side is enough), the wood bendstowards the heat.

If, like me, you find a derelict cement shellsuitable for use as a swimming pool, can it become aboat or are the surveyors correct? If it has a

substantial iron keel I can see no reason why itshould break in half when lifted. CB2 has a ferrodeck and coaming so is very unlikely to fold inwardsunless very tight slings were used without spreaders.The prediction that it would sink is presumably dueto the holes drilled by surveyors plus holes for watercooling, toilets, drains and whatever. I found 20. Imissed two, which were quickly filled from insidewith epoxy putty as the water came in. They wouldprobably have taken a week to fill the hull if left. Ahull holds an amazing amount of water, but freesurface can be a problem, as it all rushes forward or

aft, and can hit the bow or a bulkhead at just thewrong moment in a wave cycle. Just in case Isecured some drums of water in the keel space asbaffles.

Ian Hannay our past Chairman has sailed manythousands of miles with his ferro schooner Melinaand he has lent her for several Speed Week meetingsat Portland. Unlike CB2, Melina has a plywooddeck, which saves weight giving greater stability.Wood is prone to rot where damp and Ian had toundertake major repairs when he bought Melina.At 40', Ian can easily bring her in and out of

Weymouth Harbour to anchor in Portland on his

own. For less money than CB2 is likely to cost tobuild I was offered a concrete 46' ferro yacht withthe added bonus of a trip to Tenerife to collect her. Ideclined on the grounds of size. From 38' or 40' to46' everything is much bigger and costs more. Single

handing would be possible with mechanical aids, butraising the anchors or the sails becomes a serioustask. Running costs in paint, harbour dues, heavierropes and slipping costs all take a steep step upwardswithout any great increase in passage speed, range orbenefit for the purpose I expect to use the boat.

I accept that I cannot get insurance to cover anypersonal loss so I cannot take the family silver to sea.Not a real worry as it was sold to pay for legalbattles. I have a hull that is heavy, and, due to weightof deck, has only a moderate stability, therefore a lowrig or perhaps kite power is desirable. I have chosen

an air cooled diesel engine for hand starting, fueleconomy, low revs (shaft max 1000 rpm) and it canheat the cabin. I have to live with the noise and lowastern power.

Some of the ferro yachts for sale have been wellmade, well maintained and are very suitable forextended cruising. They are, in my opinion, excellentvalue, but, when you sell, will your investment bereturned? I hope to have a craft suitable and safe tocruise to Azores and the West Coast of Scotland atleast, at reasonable cost, and to last a few years.Other ferro yachts look rough, have been badly fitted

out and need major work to complete. I decided tobuild what I want on a hull I consider to be the rightsize having a fair finish and pleasing shape.

For my purpose and intended cruising waters, Iconsidered multihulls both two and three hulls.Passages would be faster, safer and more comfortable.I looked at two or three possible craft, but it seemsthat 40' is minimum to carry fuel, stores and a dieselengine. At these sizes, life in port becomes moredifficult with just one or two people. A multihullwill sit comfortably upright on mud or sand giving agreat advantage in using drying moorings; but I

would not be happy to go ashore leaving my homeat anchor in some remote bay even with fathomsof chain they tend to blow about. The final choicewas due to the ferro hull being offered, and I didnot, nor have I since, heard of a suitable low costmultihull that could meet my needs.

Michael Ellisons sailing biography runs from woodendinghies to singlehanded transatlantic racing, and is toolong to summarise! He was once the Administrator andis now the Chairman of AYRS.

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0

4

8

12

16

20

0 2 4 6 8 10 12

Beaufort Wind Scale

kn

ots

on the wind

beam reach

running

average

broad reach

Copyright 1999 Richard Boehmer

Potosi's Speeds on Different Points

of Sail

14.6

16.5maximum

via Lubbock

averages

via Prager

running in a gale

01-03 08-12 19-24 32-38 47-54 64-72

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11 wind forces) speeds. The highest values for eachof the 44 wind conditions are plotted in the twoaccompanying Figures.

Although the plots of Pragers data clearly showthat these two vessels did their best in gales (Force 7-

9) and were slowed in full gales (Force 10), for theirmaximum speeds we need to look elsewhere. For thePREUSSEN, we have a marvelous book (3) in whichthe author, Horst Hamecher, presents not only listsof all the daily positions and mileages for each of thePREUSSENs thirteen voyages but also a selection ofabstracted watch logs that contain date, watch time,distance traveled (divided by four equals speed),heading, and wind direction and force. A searchthrough Hamechers abstracted watch logs yieldedthe data also plotted in the accompanying Figure forthe PREUSSEN that maxed out at 18.25 knots for

one four hour watch.For the POTOSI, I could only find Lubbocks (4)

statement that the five-master covered 650 miles in48 hours with an easterly gale behind her. In one [4hour] watch she sailed 66 miles, giving an average of16.5 knots. Because the specific force of the galewas not stated, this speed has been plotted for themiddle two gale forces. Note that POTOSIs bestdays run of 378 nautical miles exceeded thePREUSSENs 369 nautical miles.

The simple conclusion drawn from these plots isthat a sailing vessels speed increases as wind speed

increases - up to a point - then it decreases! For twoof largest of all sailing vessels to have ever sailed the

seas, their speed peaked in medium gales; then theyslowed down as the wind speed further increased.This same situation obviously exists for smallersailing vessels but at lower wind speeds. Thisdecrease in speed is caused by either the skippers and

the crews prudent handling of their vessel (reductionof sail to trailing of warps) or by their continuousand dangerous loss of control of the vessel.

In either case, sailing vessels have a maximumspeed ultimately dictated by nature.

1. Wagner, B., Fahrtgeschwindigkeitsberechnung

fr Segelschiffe, Jahrbuch der SchiffbautechnischenGesellschaft, Vol. 61 (1967) pp.14-33.2. Prager, M., 1905, Die Fahrtgeshwindigkeit

der Segelschiffe auf groen Reisen, Annnalen derHydrographic und Maritimen Meteorologie XXXIII(January 1905), pp.1-17.

3. Hamecher, H., 1969, Knigin der SeeFnfmast-Vollschiff , pp.356-366.

4. Lubbock, B, 1932, The Nitrate Clippers, p71.

Silhouettes of POTOSI and PREUSSEN areredrawn after Alan Villiers (1971) The War WithCape Horn.

0

4

8

12

16

20

0 2 4 6 8 10 12

Beaufort Wind Scale

kn

ots

running

average

broad reach

on the wind

beam reach

Copyright 1999 Richard Boehmer

Preussen's Speeds on Different

Points of Sail

14.7

18.3

maximums via

Hamecher

averages via

Prager

various

19-24O8-12O1-O3 32-38 47-54 64-72

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ExplanationThe PAS principle is quite simple. However, it

can be embodied in at least four general types ofcraft, and some may be difficult to understandbecause of the relative motions involved. In its mostbasic form, Type 1, PAS would make use of twinvehicles, each with a wind turbine mounted on it,and some means to transmit energy between the twovehicles. One vehicle remains stationary, with its

wind turbine on, and sends its energy to the othervehicle. The other vehicle moves forward at a highspeed, with its own wind turbine off, andconfigured to create as little drag as possible. Thenthe two vehicles switch functions. In other words,they sail as a team by alternating which one producespower while stationary, and which one uses thatpower while moving forward. So this process isreferred to as power alternating sailing, or PAS.

A simple analogy with PAS is the way a personsfeet move forward when walking. The stationaryfoot is used to propel the moving foot forward, and

then they switch functions. While one foot isstationary, the other foot moves forward at abouttwice the speed of the persons body. The personsbody moves forward at the average speed of her twofeet. In principle, PAS is as simple as walking orrunning. PAS craft can move in any direction, butthe principle offers a potential speed improvementprimarily when moving upwind and downwind,since these speeds are currently much lower thanwhen reaching. However, it may eventually bepossible for PAS water craft to achieve averagereaching speeds which exceed those of current water

sailing craft.

Obviously, PAS vehicles must be designed forminimum aerodynamic and hydrodynamic drag, andminimum inertia. The cycle times should be as longas possible so as to minimize the time spentaccelerating and decelerating. Special attentionshould be paid to means of conserving andregenerating energy during the transitions from onepart of the cycle to the next.

Before presenting examples of the four general

types of PAS craft, we will briefly review the othertechniques which are currently available for sailingupwind and downwind. The emphasis will be onwind turbine boats, and also on vertical axis windturbines (VAWT), since PAS makes use of windturbines (or the equivalent), and VAWT may offersome advantages. At present, there is only oneproven technique for going directly downwind fasterthan the wind - the Bauer technique - so we willdiscuss that technique in order to establish thecontext for PAS.

Other Techniques for Sailing Upwind andDownwind

The common knowledge seems to be that iceyachts are able to move downwind, and evenupwind, faster than the wind by following a zigzag(tacking) course at high speeds. Hugh M. Barklacalculates that ice boats achieve a velocity made good(VMG) downwind of about 2.4 times the speed ofthe wind, and upwind they achieve a VMG of about1.4 times the speed of the wind. Land yachts arealso able to exceed the speed of the wind in this way,

at least downwind. Water craft using hydrofoils or

Power Alternating Sailing (PAS)

Sailboats are much faster when sailing across the wind (reaching) than they are when headingupwind or downwind. This difference is generally accepted as a normal part of sailing. Webelieve that difference might be substantially reduced, and this paper introduces a potential solution:Power Alternating Sailing (PAS). PAS craft might be able to sail directly upwind and downwindat speeds that are faster than the speed of the true wind, and faster than the velocity made good(VMG) upwind and downwind so far achieved by other types of sailing craft. (Readers will have

to judge for themselves whether the various PAS craft described below would actually function aspresented, since no testing or mathematical analysis has been done.)

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skis and sails or traction kites should be able toachieve a VMG downwind faster than the wind,although we have found no confirmation as yet.Upwind, we are not aware of any water craft whichcan achieve a VMG greater than the wind speed.

A windmill boat or windmill land yacht can movedirectly upwind because its power is initially higherthan its drag. (When stationary, the power of thewind turbine is proportional to the cube of the windspeed, whereas the drag is proportional to the squareof the wind speed.) So far as we are aware, nowindmill boat or windmill land yacht has exceededabout .5 the true wind speed into the wind (achievedby Jim Bates boat, Te Waka, in 1980 using ahorizontal axis wind turbine, or HAWT). This isprimarily because the wind turbine itself creates somuch drag while producing power. (The essence of

PAS is to separate power from drag, to divide andconquer this problem of wind turbines.)

Nevertheless, the low speed ratio upwind forwindmill craft is somewhat puzzling given thatrelative speeds upwind in excess of the wind speedare possible in theory (see Reg. Frank, and A. B.Bauer). Perhaps no one has made a serious attemptto sail directly upwind faster than the wind becauseof the especially high rotor efficiencies and very lowvehicle drag that would be required. So far,windmill boats seem to have a top speed of roughly.5 the wind speed in all directions. By tacking, fast

multihull sailboats can currently achieve a VMG towindward that is only a little better than windmillboats. So on water (and even on land), sailingdirectly upwind faster than the wind would representa significant achievement.

For windmill boats, the best speed to windwardrequires a variable pitch for both the wind turbineand the water propeller, and probably a variable geartransmission as well. The wind turbine operates atreduced power (and at a reduced tip speed ratio) soas to achieve the best thrust to drag ratio (asexplained by B. L. Blackford). A large water

propeller similar in appearance to an airplanepropeller is required for high efficiency.(Consequently, a large, modified, model airplanepropeller, while not ideal, was used by Peter Worsleyfor the water propeller of his windmill boat, whichwas powered by a variable pitch HAWT via amultiple speed bicycle gear transmission). The mostefficient water propellers have been developed forhuman powered speed record boats, wheremaximum efficiency is critical.

A vertical axis propeller with a continuouslyvariable cyclic pitch may also be used. This type of

propeller is sometimes called a Voith Schneider

propeller, but other types of blade pitch control arepossible, such as that used by GiusseppeGigliobianco. The leading edges of his VAWTblades were joined, using short shafts, to the leadingedges of the vertical axis water propeller blades, with

the result that they controlled each others cyclicpitch angles when moving directly into the wind.(For higher efficiency, his blades should perhaps havebeen counterbalanced using a counterweight out infront of the air blades.) Variable pitch fin drives(vertical or horizontal) could be used instead ofrotating water propellers, and these may eventuallyprove to be more efficient and easier to constructthan variable pitch propellers. Varying the cyclicblade pitch of oscillating fin drives would berelatively simple. Also, a VAWT might be made tofunction as an air propeller during downwind

operation if it were controlled like a Voith Schneiderwater propeller.

In the context of both windmill boats and PAScraft (which use wind turbines), experimenters maywish to know that, while there are many types ofVAWT, the class of mass balanced cycloturbines (orgiromills), with self pitching blades (like those ofSicard, Sharp, and Kirke), seem to be the mostefficient. They are equal to conventional HAWT,according to wind tunnel tests and a mathematicalmodel developed by Kirke and Lazauskas, twoAustralian engineers. The Sharp turbine is

inherently the lightest of these, which implies that itis the most responsive to large and rapid changes inthe wind velocity, and it has good starting torque, soit should, on average, achieve the most energyconversion. (Models have been constructed asbearingless rotors.) The Sicard VAWT, and theSharp VAWT (and hybrids of these two) are simplefor amateurs to construct in model sizes, althoughfine tuning them at full scale would require adaptingthe mathematical model developed by Kirke andLazauskas. (A working explanatory model of theSharp VAWT can be made in about 5 minutes using

common office materials).To pitch their blades so as to maintain an efficientangle of attack, these mass balanced VAWT achieve adynamic balance between centrifugal force (actingon a mass) and aerodynamic lift (acting on theblade), which both rise and fall at a similar rate (bythe square of the ground speed, and the relative airspeed, respectively), so instantaneous differencesbetween the two are used to pitch the blades and tomaintain them at an efficient angle of attack. In1978, a wheeled model powered by a Sharp VAWT(4 ft. in diameter, 2 ft. blade span, 4 in. blade chord)

easily went directly upwind. But it was not built for

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optimum performance (no streamlining, a fixed gearratio, only 2 blades), and the speed ratio towindward was estimated to be not more than 05.

Other potential advantages of mass balancedVAWT for windmill boats and for PAS craft include:

1) good starting torque, 2) always oriented to thewind; 3) a lower center of pressure than HAWT(a VAWT can be much wider than tall, thus allowinga larger swept area and more power); 4) the bladeorbit can stay clear of the deck and crew; 5) thestraight, symmetrical blades can be allowed to pivotfreely so as to fully feather them, thus permitting theturbine to be quickly turned off and on whilerotating; 6) the blades (by tilting their bottom endsoutward, as suggested by Rainey), and/or thehorizontal support arms for the blades (functioninglike a helicopter rotor, with the pitch controlled by

surface runners or by vertical air vanes), can be usedto create an aerodynamic balancing force tocounteract heeling and/or to create lift; and 7) forreaching, the turbine can be stopped with thevertical blades oriented to function as wingsails (firstdone by Gigliobianco around 1993), and with thehorizontal support arms functioning as wings so asto counteract the heeling forces and/or to create lift.

The Bauer Faster Than The WindVehicle

Most people who are familiar with Newtons lawsof motion are sceptical about the possibility ofsailing directly upwind and downwind faster thanthe wind, but it was first done, downwind, 30 yearsago by Andrew B. Bauer. As reported to Bauer byDonald L. Elder, discussions at the University ofMichigan around 1950 considered whether or not avehicle could go directly downwind faster than thewind using the basic approach that Bauer laterconfirmed. In the interim, Elder found that mostaerospace engineers considered the idea to be a formof perpetual motion. In fact, Bauers manager at the

time, a well-known aerodynamicist, may havemotivated Bauer to resolve the question when he saidto Bauer, I bet that you cant get wind in your face.Bauer was one of the very few people who believed itcould be done.

C. A. Marchaj, in Aero-Hydrodynamics ofSailing, states that a wheeled vehicle built by AndrewB. Bauer went directly upwind faster than the wind.That claim is inaccurate. According to Bauer, hisvehicle was designed only to go directly downwindfaster than the wind, and it did so in February of1969, as he reported in his 1969 article. The speed

of Bauers vehicle upwind was 6 mph in a 12 mph

wind, which was achieved when merely backing upthe vehicle for another downwind run.

However, when going directly downwind, Bauersvehicle, with Bauer driving, reached a speed ofapproximately 14 mph in a 12 mph wind during a

sustained run of 40 seconds, thus outrunning thespeed of the true wind. Briefly, the vehicle achievedspeeds of about 15 mph in a 10 mph wind. Bauerstresses that, due to the steep wind gradient near theground, the altitude at which the wind speed and thevehicle speed are measured must be appropriate.Our own recommendation is that, to facilitatecomparisons between different types of vehicles,both measurements should be taken at the height ofthe center of pressure of the propulsion device.Otherwise, to use an obvious example, a vehiclepulled by a traction kite could exceed the wind speed

as measured near the ground, while the kite wasactually moving slower than the wind speed asmeasured at the altitude of the kite. And near thesupporting surface, as for models, differences of onlya few feet can make a significant difference.

Bauers technique for sailing downwind was to usea variable pitch (180 degrees), two bladed, horizontalaxis propeller (with moderate blade twist), 15.4 feetin diameter and mounted at the rear of the vehicle,which was a simple wood frame with a plywood seatand foot rests. The propeller was coupled to a singlebicycle wheel via a twisted bicycle chain, using a

fixed gear ratio. The blade pitch was controlled by ahand lever hanging vertically in front of the rider,and the rider used his other hand to steer by movinga very long tiller extending to the small front wheel.Two small side wheels were used for balance.

When accelerating downwind, the pitch of thepropeller blades, initially operating as a wind turbine(even though the blade twist is in the wrongdirection), is gradually reversed so that the rotorbecomes a propeller powered by the wheels. Thenthe vehicle is able to continue to accelerate andexceed the speed of the true wind. (In his 1969

article, Bauer also explains how a boat could use itswater propeller as a turbine to spin the air propeller.)In practice, the transition from turbine mode topropeller mode is smooth and continuous. This isperhaps so because, at that speed ratio, the spinningrotor would still create propulsive drag, like a dragsail pushing the vehicle, even if the rotor were notconnected to the wheels. The Bauer vehicle can bestopped quickly by reversing the blade pitch.

On Dec. 14, 1995, Bauer demonstrated hisdownwind technique in a most remarkable way atthe office of Paul B. MacCready, President of

Aerovironment (near Los Angeles, California), and

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winner of the Kremer Prize forhuman powered flight. Bauerplaced his model, which had a 20inch diameter, 4 bladed, fixedpitch propeller, on a 5 foot long

conveyor belt that he hadconstructed, and which included avariable speed motor. Thedemonstration took place in awindless room. The model washeld in position on the movingbelt until the propeller wasspinning at full speed. Whenreleased, the model was easily ableto advance against the direction ofthe belt faster than the belt wasmoving (8 feet per second).

The speed of the belt could beslowed until the model stayed inits original position, or the belt could be slowedfurther, causing the model to be carried slowly alongin the direction of the belt. In other words, theBauer technique works better as the belt speed (orwind speed) increases. For the model on the movingbelt, the same relative motions exist as when theground is stationary and the wind is moving. For awheel-driven propeller, the two situations areequivalent. So when the model is holding itsposition on the belt, it is moving at the speed of the

wind. When it is advancing faster than the speedof the belt, against the direction of the belt, it ismoving downwind faster than the wind.

In his 1975 text, Technical Yacht Design, AndrewG. Hammitt explains the Bauer technique, and heincludes a photograph of Andrew Bauers vehiclewith Bauer beside it. Unfortunately, neither the textnor the photographs caption credits Bauer, whichinadvertently creates the impression that the vehicleis Hammitts. Hammitt reports, A tuft on the frontof the vehicle was used to show the apparent winddirection. The vehicle went downwind fast enough

so that the tuft indicated a head wind indicating thatit was exceeding wind speed. One of Hammittsgraphs shows the power coefficients for thedownwind operation of both a wind turbine and awheel-driven propeller. The two curves cross, like awide X, where the vehicle is moving downwind atabout 06 times the speed of the wind, indicatingthat above that speed ratio, the propeller mode isincreasingly more effective than the wind turbinemode. (Figures in Bauer, and Frank, show this sametransition point.) Bauer states that a crossover pointof 06 gives optimum acceleration. That photo of

the Bauer vehicle may also be found in Crackpot or

Genius?by Francis D. Reynolds.Research papers on windmill ships and boats now

take for granted the possibility of sailing downwindfaster than the wind using the Bauer technique. Butsince the Bauer technique is difficult for most peopleto understand and accept (AeroVironment, Inc. hasreceived many letters from people still insisting thatit is impossible), an explanation using a simpleanalogue model may be helpful. The relativemotions may be more easily understood using an

analogy that does not include a wind turbine or apropeller, or the motion of fluids, such as air orwater.

Our abstract analogue model is inspired by twodevices built by Theo Schmidt. The analogue modelhas two pairs of wheels which are fixed to their axles,and the axles rotate. But the wheels on one side areonly half the diameter of the wheels on the otherside. The small wheels are placed along a board orplank, such as a ruler, which is itself lying on asmooth surface, such as a table, and the large wheelsrest on the table.

Assuming good wheel traction, if the ruler ispushed lengthwise at a speed of 1V (V here meansthe speed of the ruler), the model should move twiceas fast as the ruler (2V), and in the same direction.The ruler pushes the small wheels, and the smallwheels push the large wheels, causing the largewheels to roll. In turn, the large wheels (becausethey are larger and have a longer moment arm) rotatethe small wheels. The ground speed of the largewheels (2V) equals the speed of the ruler (1V), plusthe speed of the small wheels relative to the ruler(1V). That is, 1V+1V=2V. The ruler is analogous to

the wind, the small wheels are analogous to the

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wheel-driven propeller, and the large wheels aredirectly analogous to the original vehicle wheels.

The abstract model can also be used to illustratehow a wind turbine can move upwind against thewind. If the model is inverted so that the largewheels now ride on the ruler (we will ignore thevehicle lean that results), and then the ruler ispushed again in the same direction and at the samespeed (1V), the vehicle should move backwardsagainst the direction of the ruler at 1V (and 2V

relative to the ruler). That is, 2V-1V=1V. Thisconfiguration is analogous to a wind turbine vehiclemoving directly upwind at the speed of the wind. Inthis case, the ruler is analogous to the wind, the largewheels are now analogous to the wind turbine, andthe small wheels are now directly analogous to theoriginal vehicle wheels.

Higher speeds might be reached both upwindand downwind by adjusting the relative wheel sizes(the gear ratio) of the model. Note that in both ofthese analogies, the power is derived from thedifference between the wind speed (ruler) and the

ground (table), not the difference between thewind speed and the vehicle speed.The 30 year existence of the Bauer technique

raises a question: Why have no boats been builtwhich use this technique, even though theorists nowaccept the principle as valid? The explanation seemsto be that although the technique is remarkable initself, the all-round performance of windmill boats,so far, has not been particularly impressive. Thetechnique seems limited to a narrow range ofdownwind angles. Except perhaps for ships, it doesnot seem to promise a significantly better downwind

performance than might be obtained with more

conventional techniques. Andfinally, for sailboats, upwindperformance rather thandownwind performance is the areaneeding the most improvement.

The Bauer technique is, in ouropinion, a third step towardrealizing the potential of usingwind turbines for sailing. Sailingdirectly upwind was the first step,and using a wind turbine as anautogiro sail was the second step.And PAS might become a fourthstep.

The following descriptions ofthe four types of PAS vehicles areintended only to convey what may

be possible, not what is practical.Consequently, not all the details

are included, only the basic concepts. It is assumedthat any competent technical person could fill in thedetails.

Type 1 PAS: Twin Rail VehiclesNow we will consider the PAS technique and its

potential speed advantages for going upwind anddownwind. This example is intended only toillustrate the PAS principle in a clear manner, and to

explore its potential, since the application itselfwould be impractical except for demonstrationpurposes. In this imaginary example of PAS, twostreamlined vehicles on railroad tracks work as ateam. A horizontal axis wind turbine (HAWT) ismounted on each vehicle. Each HAWT has two setsof blades (for gyroscopic balance), and both sets canbe aligned parallel with the turbines tower structurefor storage. Each HAWT produces energy onlywhen its vehicle is stationary with its brakes locked.That energy is transmitted, via a third rail, to theother vehicle, which is moving at high speed up the

track. But before moving, its HAWT, with its bladesparallel to its tower, is lowered and stored inside thevehicle so as to reduce aerodynamic drag to aminimum.

We will also assume that the necessarymechanisms (not shown) for quickly storing anderecting the wind turbine, and for stabilizing thevehicle when stationary, are installed and are underthe control of an engineer in the cabin of eachvehicle. To reduce the weight aloft of the windturbines, so as to permit quick raising and lowering,we will assume that the electrical generators are

located within the vehicles. We will assume that the

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track is level and that it headsdirectly into the wind, and that thewind is blowing at 15 mph.

Consequently, we may alsoassume, conservatively, that the

moving vehicle, with its turbinelowered and stored, travels at aspeed of 60 mph, or 4 times thespeed of the wind (ground speed).So its air speed is 5 times the speedof the wind, or 75 mph. Thisseems to be a reasonable speed toassume since we know that even ahuman being, with a very lowpower to weight ratio, can pedal acarefully streamlined humanpowered vehicle (HPV) at over 68

mph, the official record of theInternational Human PoweredVehicle Association. In a 15 mph wind, a specializedwind turbine should be able to achieve a far higherpower to weight ratio than a human being, even ifthe electrical transmission efficiency is only 50%.And the aerodynamic drag of the streamlinedvehicle, with its wind turbine stored, would be quitelow. If more power were required, the wind turbinecould be made arbitrarily larger, since its powerwould increase faster than the power required topropel it (when stored in its vehicle).

The PAS principle is applied in the followingmanner: The lead vehicle, using energy sent to it,and with its wind turbine stored, speeds down thetrack for many miles, and then pulls off onto asiding and stops. There, it locks its brakes, quicklyerects its wind turbine, and transmits electricalenergy back to the rear vehicle. The rear vehiclesimultaneously turns off its wind turbine andquickly lowers it into a stored position. Then therear vehicle accelerates to 60 mph, eventually passesthe lead vehicle, and continues speeding down thetrack for many miles until it is able to pull off onto

another siding. There, it stops and sends its energyback to the other vehicle. This procedure repeatsuntil both vehicles reach their common destination.

At the end of the journey, we calculate the averagespeed of the two vehicles working together. Thatspeed is roughly half the average speed of onevehicle, or about 1/2 of 60 mph, or approximately30 mph. That means that both vehicles, poweredonly by each others wind turbines, have gonedirectly into the wind at a combined average speedclose to two times the speed of the wind. Thisaverage speed ratio upwind (2.0) would be

considerably faster than the speed ratio to windward

achieved even by ice boats (1.4). It would be aboutfour times the speed ratio that a windmill vehicle hasachieved so far (.5). While in theory a self propelledwindmill vehicle might achieve this speed ratio, itsdesign and construction would be extremelydifficult, if it could be done at all. In contrast, thesePAS vehicles would be relatively easy to constructusing current technology since they would be,basically, just an electric train powered by astationary wind turbine.

The two vehicles could work together to go backdown the track, in the same direction as the wind, atan even higher speed, since the moving vehiclewould experience much less aerodynamic drag thanbefore. The apparent head wind when goingdownwind would be 30 mph less than when goingupwind, so the downwind speed would be about 30mph higher, or roughly 90 mph (not considering therelatively small increase in rolling friction). Theaverage downwind speed of the two vehicles wouldbe about 45 mph, or roughly 3 times the speed ofthe true wind. Again, this speed ratio downwind

(3.0) would be faster than that of ice boats (2.4).And it would be about two times the best speed ratiobriefly achieved by Bauer (l.5).

However, the Bauer vehicle might improve itsspeed ratio as the wind speed increased, as in theexample of the model on the moving belt. And theaverage speed ratio of the PAS vehicles woulddecrease somewhat since, other things being equal,the proportion of time spent traveling at full speedbetween transitions would decrease. In other words,the time required for PAS transitions would take upa larger proportion of the total travel time. On the

other hand, if the PAS vehicles simply went farther

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between transitions, they could retain their speedratio.

Even higher speed ratios might be possible usingPAS since there are ways to increase the power todrag ratio of a PAS vehicle team. For instance, inthis example, each PAS vehicle could be constructedas a train with many cars, and each car could beequipped with its own wind turbine. Whenoperating the wind turbines, the cars would bespread out along the track (about 10 turbine

diameters apart, as is done on wind farms so as toavoid interference effects), thus multiplying thepower of each train an arbitrary number of times.But the cars would close up into a normal trainconfiguration when moving (with the gaps betweencars covered to minimize drag), so as to cause only arelatively small increase in aerodynamic drag overthat of a single vehicle (car).

In the above example, if the wind were blowingfrom the side of the track, the average speed ratio ofthe twin PAS vehicles would be somewhere betweentheir average speed ratios upwind (2.0) and

downwind (3.0). Just for the purpose ofcomparison, consider that with the wind comingfrom the side, if each vehicle used an efficientwingsail, they could move simultaneously at a speedexceeding 4 times the speed of the wind, as wasdemonstrated by the Amick Windmobile. It is forthis reason that when sailing across the wind(reaching) windmill boats and PAS craft would, inmost cases, revert to the use of direct sailingtechniques (wingsails, autogiros, traction kites, etc.).On the other hand, as the above example illustrates,there is no obvious limit on the average speed ratio

of PAS craft. And, when reaching(and perhaps even when goingupwind and downwind), PAS craftmight combine other sailingtechniques with PAS to further

increase their speed.

Type 1 PAS: Twin Craft onWater

On water, this same basictechnique might be used. Again,this example is intended to showwhat may be possible, not what ispractical. The two craft might flyjust above the water using wings inground effect (WIG; examplesof such craft may be found on theInternet) when moving at high

speeds (with hydrofoils or a hovercraft hull for takeoff), and a sea anchor (possibly a water turbine andtemporary water ballast) or a bottom anchor (inshallow water) when converting wind energy. Thetwo craft are connected by a very long, wellinsulated, electrical wire, which always floats still onthe water, that is reeled in and out only by themoving craft (so as not to drag the wire through thewater). Since the use of an electrical wire on waterwould be unwise due to the possibility of shocks,

plus the hazard of other boats cutting it, the conceptis not very practical. But it might work well enoughin open water for the average speed upwind anddownwind to substantially exceed the speed of thetrue wind. (The same technique could be used onland and ice.)

Given the much higher power required on waterthan on land, some form of power kites might beused instead of conventional wind turbines. Apower kite would generate power by sweeping backand forth across the wind at high speed (perhapsunder computer control using various sensors).

Small wind turbines are mounted on the kite(perhaps tip vortex wind turbines, which have beenused on a small airplane to recover 20% of theenergy normally lost to wing tip vortexes). At highspeeds, the wind turbines can be quite small and stillproduce high power, since their power isproportional to the cube of the speed of the relativewind, and kites can achieve air speeds of 100 mph.The electrical wires are then held out of the water bythe power kites. The wires connect each craft toeach kite. The moving WIG craft tows its kite, with

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the kite in a low dragconfiguration. But even powerkites would be suitable only inopen waters.

Type 2 PAS: A SingleVehicle With Two

Alternating Wind TurbinesType 2 PAS vehicle

configurations require only asingle vehicle with two windturbines (or the equivalent) whichalternate their off and oncycles. Their speeds wouldprobably be lower than that oftwin PAS vehicles, due to more

frequent cycles. The two windturbines move forward one at atime (when off, and configured to produceminimum drag), but both are mounted on the samevehicle - on long, parallel guide tracks, or at the endsof a very long beam that moves forward like a doubleended paddle, etc.

An example: A wheeled vehicle using anextremely long beam has a Sharp VAWT, and a drivewheel, at each end of the beam. Each VAWT powersthe drive wheel at the other end of the beam,through a clutch. Power is transmitted using

mechanical means - drive shafts, or chains, or cranksand cables, etc. Each end of the beam alternatelyswings forward through about 90 degrees of arc.The crew, in a separate streamlined cart, is towedusing a very long tube, which is pivoted at themidpoint of the beam. (The tube also serves toprevent the beam from tipping in response to windpressure on the VAWT.) This arrangement wouldminimize the inertia of the ends of the beam. (Overwater, the beam might function as a wing in groundeffect to reduce or eliminate the water drag of theadvancing end of the beam.)

The crew requires at least two control lines. Eachcontrol line turns one wind turbine on and theother turbine off, while connecting the onturbine to its drive wheel, and disconnecting theoff turbine from its drive wheel, plus applying abrake to the stationary wheel, which acts as a pivotfor the beam. So the off turbine continues torotate but produces no power, and low drag. Turnsare made by swinging one end of the beam forwardmore than the other end. As mentioned previously,special attention should be paid to techniques forconserving and regenerating energy.

Even drag sails could be used to go directly

upwind, although the vehicle would be just acuriosity, a toy, and its speed ratio would probably beless than 1. It would use a long beam as a lever toadvance into the wind in a manner somewhat similarto the example directly above. The long beam has apivoting drag sail at each end, and a wheel mountedat about 1/4 beam span from each end. A casteredtail wheel (for stability) is mounted on a short tubeextending out behind the middle of the beam. Thedrag sail at one end is pivoted perpendicular to the

wind, while its wheel is locked and serves as a pivotto swing the other end of the beam upwind until thebeam is at about a 45 degree angle to the wind. Theadvancing drag sail is turned parallel to the wind forminimum drag, and its wheel rolls freely. And then,in turn, the other end of the beam swings forward 90degrees in the same manner. A wind vane mountedat the middle of the beam is used to trip amechanical toggle switch, which turns the drag sailsand the wheel brakes on and off whenappropriate.

Type 3 PAS: A Single Vehicle with PowerSources Which Cycle On and OffWHILE Continuously Moving

This type of PAS vehicle can be confusing, so wewill consider both a complex example and a simpleexample. The complex example of a Type 3 PASvehicle is a wide trimaran equipped with two VAWT,which are triangular (in plan), both always on, andwhich rotate a water prop. Two such triangularVAWT are mounted side by side to form a widediamond shape (in plan), rather like the outline of

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wings as wide as the trimaran. Each wing leg isabout twice as long as its base leg. The base legs areabove the central hull of the trimaran. Both VAWTalways face toward the front (bow) of the trimaran,when moving either upwind or downwind. Eachturbine uses vertical blades (wingsails) supportedbetween two continuous belts, one above the other,that form the triangular outline of each VAWT.(The tip speed ratio of the blades would be about 4,and a control belt would collectively adjust their

pitch angles by loosening or tightening their mainsheets.) The blades move forward (always toward thebow of the boat) only when they are on the shorterbase legs. On the base legs, the blades move directlyinto the wind (they are off) when the boat ismoving upwind, and directly away from the windwhen the boat is moving downwind. The beltsalways move in the same direction.

Thus, the blades produce power only when theyare on the wing legs of the triangles - moving outand back and rearward relative to the boat whenmoving upwind, and the same when moving

downwind. The result is that when the blades areproducing power, they do not advance relative to thewater, so as to avoid the usual increase in rotor dragwhen moving upwind, and the usual decrease inrotor power when moving downwind. In otherwords, each blade moves rearward, while producingaerodynamic lift (they are on), at the same rate thatthe boat moves forward. So each blade, whenproducing lift, would function like the blade of astationary HAWT, or like a sailboat reaching backand forth directly across the wind, while the boatitself was heading upwind, or downwind, as fast as

the speed of the wind. If, when producing lift, each

blade traced a line on the water,the blades would leave a steppedsequence of straight lines, or rows,perpendicular to the boat andadvancing in the direction of the

boat, both upwind and downwind.The simple example of a Type 3

PAS vehicle is just a toy. It wouldgo only downwind, and it wouldbe unlikely to go downwind fasterthan the wind since it uses onlydrag sails. But it would probablygo directly downwind faster thanis possible using conventional dragsails, and it is of interest for thatreason. In this case, the two powersources are two drag sails that

alternately open and close, whilethey also move forward and

rearward relative to the front wheels of the vehicle,since they are mounted at the trailing ends of crankarms connected to the two front wheels.

The two crank arms are connected to outsidefaces, near the rim, of the two large front wheels,which are fixed to a common axle. The crank armpivots are offset 180 degrees from each other, so onecrank arm moves forward while the other movesrearward (relative to the front wheels). At theirtrailing ends, the crank arms are each supported by a

small wheel. Above each small wheel is a tallrectangular sail which opens and closes like a book(binding forward). The sails open in response to atailwind, and close in response to a headwind.When closed, they have a streamlined shape facingdownwind.

At the point where a rolling wheel touches theground, that point has no forward movement.Consequently, a crank arm pivoted near that point willmomentarily come to an almost complete stop relativeto the ground. A sail mounted at the other end of thecrank arm would therefore also come to an almost

complete stop, and that would subject itto high dragfrom the wind, thus giving the sail, and the wheels, astrong push (even if the wheels were moving faster thanthe wind). So the sails push the wheels, and therotating wheels, in turn, oscillate the sails. Thispumping motion of the sails functions like a verycrude sort of propeller, which would be more obvious ifthe vehicle were placed on a moving belt in a windlessroom. Seen in that context, this toy PAS vehicle mightbe described as somewhat similar to the Bauer vehicle -but using only a drag type propeller, rather than a lift typepropeller like the Bauer vehicle. (An