Catalyst - Amateur Yacht Research Society · 1 30.64 Nick Beaney 2 29.19 Richard Ashenden 3 28.91...

CatalystJournal of the Amateur Yacht Research Society

Number 6 October 2001

CatalystJournal of the Amateur Yacht Research Society

Number 6 October 2001

OCTOBER 2001 1

Contents

Events3 Weymouth Speed Week

5 Ronde om Texel

7 Weymouth AYRS Meeting

18 Wind of Change 2001 - a personal viewChris Evans

Design13 Quarterline – easy build GRP yacht hull shapes

Tom Peat

16 RevolutionKim Fisher

Speedsailing24 From Hulls to Boards, Now Foils and Planing

Richard Boehmer

24 Hyperwind SailingDr Barney Kenney

Regulars27 Letters

29 Notes from Toad HillA solar panel experiment Frank Bailey

32 Catalyst Calendar

Cover Photo:John Perry’s hydrofoil close to

lift-off at Weymouth Speed Week2001. Wind about Beaufort F2

to F3.

Photo: Josephine Street

2 CATALYST

CatalystJournal of the

Amateur Yacht Research Society

Production Team —Simon Fishwick (Editor)

Sheila FishwickDave Culp

Specialist CorrespondentsAerodynamics—Tom SpeerElectronics—David Jolly

Human & Solar Power—Theo SchmidtHydrofoils—George Chapman

Instrumentation—Joddy ChapmanIceboats & Landyachts—Bob Dill

Kites—Dave CulpMultihulls—Dick Newick

Speed Trials—Bob DownhillSteam Power—Lord Strathcona

Structures—Keith BurgessWindmills & Turbines—Jim Wilkinson

Catalyst is a quarterly journal of yacht research,design, and technology published by the AmateurYacht Research Society, BCM AYRS, LondonWC1N 3XX, UK. Opinions expressed are theauthor’s, and not those of AYRS. AYRS alsopublishes related booklets.Contributions are welcome from all. Email themto [email protected], or send (atyour risk) disks or typed copy with illustrationsto the Society’s office. AYRS can take noresponsibility for loss or damage.AYRS subscribers receive both Catalyst and thebooklets. Subscription is UK£20 or US$30 perannum for a Full Member, £10 or $15 forstudents and retired members. Subscriptionrequests and all other queries to be sent to theAYRS Office, BCM AYRS, London WC1N 3XXUK, phone/fax +44 (1727) 862 268 or email:[email protected] is a UK Registered Educational Charity(No 234081) for the furthering of yacht science.

Website: http://www.ayrs.org

© 2001 Amateur Yacht Research SocietyBCM AYRS, London WC1N 3XX, UK

All Rights ReservedISSN 1469-6754

Two forthcoming AYRS Events

Both of these are in the UK. — If there is anythingbeing organised in the US in the near future, no-onehas told Catalyst!!

The AYRS Annual General Meeting will be held on 12thJanuary 2002 at 8pm at the London Corinthian Saling Club,Upper Mall, London W6. All are welcome, but only paid-upmembers are entitled to vote. Further details will be sent tomembers, or contact the AYRS Honorary Secretary.

A Boat Building Day will be held in the Thorpe VillageHall (between Staines and Chertsey, Surrey, UK) on 17thFebruary 2002 from 9.30am to 5pm.. Bring your projectalong, or if you cannot bring it, bring some pictures (OHP or35mm slides for preference) and be prepared to talk about it!(See page 28).

The end of the yearThe equinoxes – time of mists and mellow fruitfulness

in the northern hemisphere, but also the time ofequinoctial gales. Time therefore for speedsailors to packup the craft they have been building and head for thetrials waters. Time to find out whether those carefullyconstructed ideas really do stand a chance of taking thatelusive record.

In Europe, that means going to the Weymouth SpeedWeek, site of the first regular speed trials run by AYRS, atradition continued by Bob Downhill and his team. Thisyear’s speed trials were blessed with wind, perhaps too muchfor some people whose boats were not up to the task.Crossbow’s 1980 record still stands, but only just.

Time now then to think about next years developments,and maybe to write up this year’s work for Catalyst. Tell uswhat you have done, and what you will do next.

In the southern hemisphere of course, summer is justbeginning, and it’s time to come out of the workshop andstart some gentle testing. But maybe you people too couldtear yourselves away from the Barbie of an evening and tellus about it. Catalyst has few southern hemispheresubscribers, but those few we know are active.

We would love to hear from you all.

OCTOBER 2001 3

News

An innovation this yearwas the setting of a short,200 metre, inshore course.This being close to thebeach providedsignificantly smootherwater than the 500 metrecourse in the middle ofthe harbour, so it is notsurprising that speedswere higher. (NickBeaney’s best speed on thelonger course was 30.6knots). This was acontroversial move — theshorter course length isnot currently recognisedby the World Speed SailingRecords Committee. Itwas felt that there was ahigh chance of anexceptional gust carrying asailor at high speed all theway down such a shortcourse, thereby setting arecord by luck rather thanby skill. Such help over a500m course was felt to beless likely.

It has to be said though that when the WSSRCmade that decision, likely records were of the orderof 20 knots and a run would cover the course in 45seconds or so. Nowadays, a record run over the longcourse would take less than half of that time, and theargument is less strong. A short meeting of theboardsailors, observed by Michael Ellison forWSSRC, suggested that short “sprint” courses

should be used, toencourage speed sailing,but not recognised forthe world record. Thereis a view however thatsuch inshore coursesneed to be set to allowboats as well as boards totake part, and with aprescribed minimumdepth of water to avoidshallow-water effects.

For many of the boatentrants though suchconsiderations weremerely academic.Breakages were endemicin such strong winds, ofthe 20 boats entered,only 12 managed tosurvive unharmed longenough to make timedruns. Torix Bennet’s SeaSpider blew over in theboat park despite beingheld down by severalblocks of cement. GuyHawkin’s big proaMade in Dubai (a very

interesting design that we hope to describe in afuture issue of Catalyst) was thrown onto the rockleaving the slipway and broke its rudders, ChrisEvan’s Triton Chariot achieved a spectacular capsizethat fractured a float, and Patrick Mayne’s Foiler 21Speedbird also capsized, breaking the upper mast,apparently on impact with the bottom!

Weymouth Speed WeekCrossbow�s record stands � but only just!

After a number of years of indifferent weather, WeymouthSpeed Week this year had wind!

The opening Saturday saw winds of about Force 4, but by Sunday, gusts of up to 35 knots werebeing observed, and this continued through the Monday and Tuesday, easing off somewhat towardsthe end of the week. Not surprisingly, the windsurfers had a great time. Nick Beaney recorded thehighest speed of the week, 35.2 knots, on the Monday — just short of Crossbow’s Portlandrecord of 36 knots set in 1980. The most interesting challenge of the week came from thekiteboarders. Chris Calthrop set a speed of 33 knots in only six runs. Injury prevented him fromdoing more, but it is clear signal that the kites are a force to be reckoned with.

Nick Beaney, photo: R M Ellison

4 CATALYST

Weymouth Speed Week

500 Metre CourseKnots Entrant

1 30.64 Nick Beaney2 29.19 Richard Ashenden3 28.91 James Paine4 28.60 Pete Martin5 28.47 Angus HitchinBoats28 19.34 Alan Blundell Vari Scari triscaph29 16.79 John Peperell Catapult30 16.06 Alex Montgomery Catapult32 15.34 Neils Haarbosch Flaxcat34 14.34 Torix Bennett Sea Spider triscaph35 14.27 Chris Evans Foiler 21 Boomerang36 13.93 Patrick Mayne Foiler 21 Speedbird37 12.56 Fred Ball CopyCat38 12.22 Philip Middleton Triton Chariot39 11.86 Neils Haarbosch Kiteboat40 11.48 Slade Penoyre Catapult + hapa41 9.03 John Perry 2-foil trimaran

200 Metre CourseKnots Entrant

1 35.22 Nick Beaney2 34.52 Stacey Vass3 33.54 James Paine4 33.38 Richard Ashenden5 33.38 Chris Calthrop KiteboardBoats28 17.61 Alex Montgomery Catapult30 11.54 John Peperell Catapult31 9.45 Fred Ball CopyCat32 9.07 Neils Haarbosch Flaxcat33 6.68 John Perry 2-foil trimaran

ResultsOverall results were dominated by sail- and kite-

boards. No less than 27 of them exceeded the fastestboat speed of 19.34 knots set by Alan Blundell’s Vari

Scari on the long course and the same was true forthe inshore course. The top-ranking ’board resultsand all the boat results are given below.

SPEEDBIRD under tow after breaking the mast

Torix Bennett’s SEA SPIDER did not complete a runThe Dutch Kiteboat at speed

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OCTOBER 2001 5

Events

Ronde om Texel 2001The Round Texel race this year was a test of concentration and endurance — concentration by the

competitors as they searched for the next tiny puff of wind to waft them on their way, and enduranceby competitors and spectators alike as they roasted in the unrelieved sunshine. Of the 700 or socompetitors who started, only 20 finished the course, the rest having fallen by the wayside.

The island of Texel lies on the north edge ofHolland. On one side is the North Sea; on the otherthe Waddenzee between a string of islands and themainland. The Round Texel race starts on North Seaside, passes round the north end of Texel, down theWaddenzee and back out to the North Sea to finish.On a good day, the fleet of boats have the tidalcurrent behind them all the way round, especiallywhen passing through the narrow gaps between Texeland adjacent lands. This though was not to be agood day.

The Round Texel race comes at the end of a week-long festival of catamaran races. For most of theweek, the westerly winds had been good, becomingquite strong as the sea breeze set in behind them.Out in the North Sea a swell had set in, producingsome surf on the beaches of Texel, but nothing thatthe boats could not handle in the prevailing winds.

The morning of the big race dawned fine andclear, but the wind was light and had backed to theeast. On the beach and on the start line the swell wasstill running, leaving competitors struggling topaddle and sail their way out through the surf. Firstof the casualties was AYRS’ own Slade Penoyre in hisCatapult – pushed backwards onto the beach by awave, his rudders caught on the sands and his tillerbroke. Others had similar problems. I saw one Formula 20surfing sideways in, narrowly missing a navigation beacon.

Out at sea, the light winds made it difficult forboats to manoeuvre, and many were drifting over the

start line. Still, it was the way they wanted to go,and with 700 boats lining up, there is no realprospect of a general recall, although individualscould be and were sent back. Eventually the fleet wasstarted, helicopters flying down the length of the linefiring flares to signal the start to those out of earshotof the shore, and the leaders stretched away north-eastwards towards the tip of the island.

Those of us on shore took to our bicycles,scooters and cars (Texel is an excellent spot forcycling being well provided with cycle tracks) andcrossed the island expecting to see the leaders passingthrough the narrow gap into the Waddenzee. Butacross the hazy Waddenzee there was no wind, thesea was glassy-smooth, and of catamarans there wasno sign.

Eventually, a small string of sails appeared in thedistance, moving oh-so-slowly along the horizontowards the turning mark at the end of thesandbank. For an hour we sat and waited but onlyabout 40 boats appeared struggling against the ebbthrough the channel between Texel and the nextisland. The rest had failed to make it.

With the ebb and the wind, such as there was,behind them, the leaders made better progress downthe inside of Texel until by the time they reached theother end, the sea breeze had set in from the NorthSea, and they beat up the coast, some even managingby careful control of weight and sheets to fly a hull forthe photographers as they crossed the finish.

Ronde om Texel 2001 – the Start

6 CATALYST

Ronde om Texel

Handicap ResultsSail No Class Helm/Crew Country Corrected Time729 Formula 18 Gavin Colby/Cori Camenisch AU 7.38.043222 Formula 20 Hans Bouscholte/Peter Desmedt BE 7.49.04776 Formula 18 Sascha Larsen/Wouter Jongeneel NL 7.49.24269 Formula 20 Han Verdeijen/Ruud Faase NL 7.54.2759 Formula 20 Peter Vink/Sven de Laaf NL 7.55.28747 Formula 20 Maarten Mol/Peter Bloemsma NL 7.55.44227 Nacra Inter 20 Paul Hamers/Koen Spoorenberg NL 7.58.22252 Formula 20 Willem van der.Geest/Robert van Rijn NL 7.58.45101 Formula 20 Arien Hofman/John Zuijderwijk NL 7.59.011561 tornado Remco Kenbeek/Herwin van de Kamp NL 8.00.0717 M18 Hakan Frojd SE 8.01.0432 Formula 20 Vincent Huntelman/I.F. Harskamp NL 8.01.422 Formula 20 Leen den Hollander/Sander Mulder NL 8.02.19159 Tornado Xander Pols/Leonique Faas NL 8.02.26141 Formula 20 Bas van Loon/Runar Damoiseaux NL 8.02.53111 Tornado Sven Karsenbarg/M. Heemskerk NL 8.06.311281 Nacra Inter 20 Cor Salverius/Tom Hardeman NL 8.12.33208 Formula 20 Harry van Rhijn/Klaas van Duin NL 8.36.0322 Dominator Piet Heemskerk/Antje Hoogendijk DE 8.41.12

Report by AYRS

Texel Rating Rule 2002 (version 3)You should know that the Texel Rating committee in Holland has decided to change the basic formula a bit

and change some other elements in the Texel Rating Rule. The most complete information is to be found onthe two websites mentioned in the text below.

The basic Texel Rating formula was developed in 1984. In 1993 the formula was updated to Version 2.After another nine years, the rating committee in Holland have decided to give the formula another update.This is done to lessen a slight disadvantage given to very lightweight multihulls by the existing formula. Thesevery light boats now get higher TR numbers. As a consequence heavier craft get lower TR numbers. Allnumbers are relative. By this process, the total range of numbers given has been narrowed a bit.

The basic formula now becomes:

TR number = 100 / (0.99 * RL0.3 * RSA0.4 / RW0.3)

The power for RW has been lowered from 0.325 to 0.3. The constant factor from 1.15 to 0.99.Another change in the rule is in the way to handle spinnakers for the beach catamarans with LOA <= 22 ft.For these catamarans, if a spinnaker is to be used, 4 pts will be deducted from the calculated TR number.For catamarans which use spinnakers larger than the stated limits, the spinnaker sail area will be rated as

11% effective, so that percentage will be added to the total sail area. This means that the deduction will alwaysbe more than for spinnakers which are within the limits. The deduction depends on the size of the spinnaker.

More details can be found on the website www.texelrating.knwv.nl about the beach catamarans and on thewebsite www.ctcnederland.nl about all cabin multihulls, catamarans and trimarans

For any questions contact Geert Ruesink <[email protected]> (the webmaster for the beachcatamaransand member of the Texel Rating committee) or me <[email protected]>, or, better, email both of us.

Nico [email protected]

First to finish were the Formula 20s of Peter vanDeventer & Chris Ktijthe, Mitch Booth & HerbertDerksen and Jacco Salman & Marten Guyt. But theRonde om Texel is a handicap race and the winners

were not far behind them – the Formula 18 of GavinColby & Cori Camenisch. All in all it took theleading boats 7½ hours to get round – well short ofthe course record.

OCTOBER 2001 7

Events

WEYMOUTH SPEEDWEEK WEDNESDAYEVENING SEMINAR.

Report by John [email protected]

On the Wednesday of Weymouth Speed Week, AYRS usually holds a discussion meeting onspeed sailing at which a number of entrants are invited to outline briefly their projects. My noteson this meeting are as follows.

SLADE PENOYRESlade continues to experiment with towing hapas

alongside various types of sailing craft. A hapa is awing, or hydrofoil, towed underwater to generate aforce in the towing line which resists leeway and canalso reduce or eliminate heeling under sail. Thereare various hapa designs utilising different methodsfor controlling the depth of immersion of thehydrofoil.

Last year Slade showed us a hook shaped hapa, aspreviously used by Didier Costes and others. Thistype of hapa has the main hydrofoil surface curvedalong the span so that as it rises out of the water thepart remaining in the water becomes morehorizontal to provide an increasing downwardscorrective force. This year Sladeshowed us a prototype tee shapedhapa, the main hydrofoil beingthe cross arm of the tee which isconnected to the tow line by aperpendicular strut whichpenetrates the surface at an angleinclined towards the towing craft.A tail plane mounted behind thestrut is slightly angled to turn thestrut to drive it deeper into thewater. Stability is achieved bybalancing this against the effect ofa small canard which skims on thesurface and is mounted on an armabove the surface and projectingforward from the strut. This hassome similarity to the hapasconstructed by Ashford andBiegler.

Slade’s new hapa was tested bytowing alongside a motor boat

during this Speedweek. These early trials showed thatit behaved in a stable manner, at least in calm water.

An obvious application for a hapa is to reduce oreliminate the heeling of a monohull sailing yacht butSlade also envisages hapas to be towed by asailboard, perhaps with an attachment to the boardsailor’s harness. The hapa would take over from theskeg of the board in resisting leeway and because itcould remain effective when the board is airborneperhaps some spectacular jumps clear of the waterwould be possible. Slade would be keen to hear fromany board sailors who would like to work with himto develop this idea. ([email protected])

John Perry at Weymouth demonstrating that it is possible to windsurf towinga hapa. The board is a Catapult cat steered by Slade. The rig is a genuine

board rig, We completed a run over the course. It was not easy.

8 CATALYST

Weymouth AYRS Meeting

CHRIS EVANSChris again brought his 24 foot

day-sailing trimaran, Triton Chariot,to Speedweek. This fast and eleganttrimaran is fitted with retractableinclined surface piercing hydrofoilsoutboard of each float and a horizontalfoil on the bottom of the rudder.The craft has not yet lifted entirelyon the foils but no doubt thehydrofoils do provide useful lift andheeling resistance to supplement theeffect of the fairly small floats even atspeeds below the take off point.

Unfortunately the craft suffered amishap during this Speedweek andwill have to be transported back toChris’s workshop in Germany forquite extensive repairs. The authorof these notes happened to be aboard at the criticalmoment. Chris had just completed a run across thespeed course and was turning to gybe when I realisedthat I could see the seabed racing underneath,meaning that the water was getting a bit thin. Ishouted a warning but then the lee hydrofoil caughtthe bottom causing the craft to pitch forward. Thebow of the lee float then dived several feet into thewater, crashing into the seabed and the bow of themain hull also hit the seabed a moment later. I thinkwe were close to pitchpoling but recovered and sailedback to the slipway, settling deeper in the water sincesome of the watertight compartments were damaged.

The forward third of one float was broken awayand the bows of the main hull were split andleaking. There was no damage at all to the hydrofoilwhich had hit the seabed, although the hydrofoilmounting was slightly twisted.

The hulls are round bilge ‘tortured’ plyconstruction with epoxy fillet joints. Inspection ofthe damage showed that the epoxy joints were not aweak point in the structure since all the fracturesappeared to be in the timber itself, not at the joints.Chris was adamant that the craft will be rebuilt,possibly with slightly longer floats than before.

DIDIER COSTESDidier’s main interest these days is in airships and

he is currently completing a two person 18m lengthhelium filled airship as a commercial venture. But healso continues to work on his ‘Exoplane’ series ofexperimental sailing craft the latest of which hebrought to this Speedweek although unfortunately itwas damaged before it was able to get sailing.

Didier gave us a history of his development of

Didier Costes - Exoplane 5

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OCTOBER 2001 9

Events

this type of craft. The basic concept is a proa with aninclined sail mounted well to leeward of a main hull.There is a tiny lee hull under the sail but when thecraft is sailing this will normally be lifted clear of thewater. The main hull is fitted with inclined keels/rudders which lift typically about half the totalweight when sailing fast, the rest of the weight beinglifted by the inclined rig. At least one of the keels arecurved along the span. As for Didier’s hapas, thiscurvature controls the flying height. Didier has inthe past achieved 25 knots with this type of craft; forfurther details see Didier’s article in the last editionof Catalyst, the AYRS Journal.

Didier also briefly mentioned his work on airshipsincluding successful trials towing a hapa with anairship, the engine of the airship being switched offand the body of the airship acting as a sail, the hapaas a keel. Apparently an airship has a lift to dragratio of around 4:1 when inclined at a suitable angleof attack to a headwind – this is better than somesailing rigs and it also weighs nothing and does notnecessarily impart any heeling moment onto a watercraft which is in tow.

GUY HAWKINSGuy and his team made a first appearance with an

impressive new craft at this Speedweek. Guy wasquick to say that much of the basic concept of hiscraft was shared with the previous speaker’s‘Exoplane’ and other earlier projects. Like theExoplane, Guy’s craft is a two-way proa with inclinedlifting rig set well to leeward of the main hull. Therig is a single wingsail with flexible membranesurfaces tensioned over transverse ribs mounted on aleading edge spar and a main spar. The connectionbetween the rig and the main hull is a 12m long

streamlined oval-section beam mounted horizontallybetween the main hull and the base of the rig. Thisspar swings freely about a vertical axis bearing at themid-length of the main hull. This free rotation isintended to prevent the rig forces from overcomingthe steering controls.

The craft is to lift clear of the water at speed bymeans of cruciform shaped lifting and steeringhydrofoil units at each end of the main hull togetherwith the lift-force component from the inclined rig.The hydrofoils can be rotated about 180 degrees forsailing on both tacks. The hydrofoils are expected tooperate fully ventilated and it is hoped that this willavoid steering difficulties caused by transitionsbetween ventilated and non-ventilated operation. Athigh speed the lifting surfaces of the hydrofoils mayplane on the water surface.

The whole craft is well finished and the structureis almost entirely carbon fibre reinforced composite.Guy estimated that there was still three weeks fulltime work to do before it would be possible to startsailing trials so there was no possibility of seeing it inaction on the Speedweek course. The hulls and crossbeams were assembled and briefly launched and thisdid show up a weakness in the mountings for thehydrofoil units which were broken during this initialfloatation test but I don’t think it will be long beforethese are replaced with something a bit stronger.

The project benefits from industrial sponsorshipin Dubai and the craft carries banners declaring‘Made in Dubai’. Other sponsors include a finiteelement analysis software house and the wholestructure has been the subject of a study by finiteelement analysis. The main site for sailing trials willbe on a remote Scottish Loch. The team areconfident that they are in contention for the worldspeed sailing record.

Dr. Guy Hawkins and his team assembling his exotic craft for the first time. A very well built proa that had peopleguessing for days as it stood in the car park on its trailer waiting for calmer weather to begin the first

assenbly. There is a rudder at each end which is designed to 'castor' when the craft is shunted. The cross beam isfree to swing and the understanding is that it will find its own point of balance.

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JEAN HURTADOJean again brought his tri-hulled

craft from France, stowed neatly insections on a custom-made roofrack. This craft assembles into atetrahedral structure with largediameter but thin walled alloy tubesradiating from a central junction tothe extremities. Steel cables link theouter ends of the tubes and hold thestructure rigid. One of these cables isa stay for a triangular sail which hasa steeply inclined luff so that when itis filled by the wind it generates asubstantial lifting force on the wholecraft as well as a forward drive force.

Unlike many speed sailing craft itis very robust and it is also not asheavy as you first imagine. All thealuminium work is to a good standard and neatlywelded together.

The craft floats on three small aluminium drumsattached to the lower corners of the tetrahedronstructure, these drums being angled to provideplaning surfaces. The planing surfaces are set at quitea steep angle of attack to the water and for a futuremodification Jean plans to reduce this angle ofattack. Jean explained that the concept was inspiredby a 15 foot sailing boat with a generous 36m2

lifting rig which was built by Pilcher, an aviationpioneer, in 1894.

I was watching Jean’s craft as it made its best rundown the speed course and I saw that on two orthree occasions the craft did start to lift off the water.At these moments the craft accelerated dramaticallybut the small low aspect ratio fins and forwardmounted rudder then became ineffective causing thecraft to veer off course and slow down again.

The audience were amused by Jean’s comment “my boat is like a bus, not like a taxi – a taxi goeswhere you ask it to, my boat, well ….”

JONATHON BARTONThis was Jonathan’s first visit to Speedweek and

he is already toying with ideas for building a speedsailing craft. He has experience of sailing Tornadocatamarans and sail boards and he showed us aquickly made model to illustrate some preliminaryconcepts.

This model had a single narrow hull, based on theTornado hull shape and a small float set on a longarm which could move fore and aft as well as

somehow moving from one side of the hull to theother when tacking, perhaps it could slide acrosswhich would presumably require a small float ateach end. The rig would also be movable fore and aftand cantable from side to side by means of variablelength stays.

Obviously early stages, we hope to see him backwith an interesting new craft.

JOHN THURSTONJohn showed us a sailing model of a four hulled

craft fitted with a cascade of five rigid wing sails,that is a set of wings mounted along side each other.A full size version might have as many as sevenwings. The wings are mounted on a cross beam atthe rear of the craft and two of the small hulls are atthe extremities of this beam. The third hull ismounted from a cockpit structure which extendsforward from the centre of the cross beam. All thesethree hulls carry hydrofoils which have an invertedvee shape, presumably they are surface piercing. Themodel also included a fourth hull aft which wasneeded to obtain some extra bouyancy at model scalebut which would not be included in the full sizeversion.

The aft cross beam rotates on a vertical axis pivotas well as the sails each rotating on a vertical axisfrom this beam. John explained that this allows thesails to extract maximum energy from the wind bycovering the maximum area as seen in a projectionfrom the direction of the apparent wind. The modelwill in due course be fitted with a radio controlsystem for sailing trials.

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Events

MICHAEL ELLISONMichael briefly updated us with his progress on

fitting out his 38 foot ferro-cement monohull yachtbased on a hull which he found abandoned in aquarry.

The three-cylinder air-cooled Lister diesel is nowinstalled and Michael commented that he had notfitted a silencer since he so much liked the sound ofthe exhaust. The yacht will possibly be driven by akite rig and the eventual aim is long distancecruising.

NIELS HAARBOSCHNiels is the leader of the Dutch team which

produced the Aeroskimmer catamaran a few yearsback and has also been responsible for a varied rangeof small experimental craft. Niels told us about theirFlaxcat which is the most conventional boat I haveseen from this team.

What makes the Flaxcat different is that it is aneco-friendly construction, the hulls being mouldedusing resin reinforced with flax, the natural fibreused to make linen. Niels considers that flax-reinforced resin can achieve a similar weight andoverall strength to glass reinforced resin. Flax fibresare not as strong as glass but they have a lowerspecific weight at 600kg/m3 compared with 2800kg/m3

for glass and this allows a thicker laminate for agiven weight which helps panel stiffness.

The flax fibres are supplied as a randomlyoriented mat and Niels said that this is not verysuitable for hand laminating. If you try to roll resininto it with a laminating roller the roller just getslarger and larger and the laminate gets thinner!Instead the Flaxcat was built using resin injectionmoulding.

This means that the mat of fibres was fitted into afemale mould, a vacuum bag was applied over thefibres and a tube connection made between thevacuum bag and a bucket containing a carefullyjudged quantity of resin. When vacuum is appliedthe air is drawn out from the space between thefibres and replaced with resin. Resin to fibre ratio isgood and there is little wastage of resin.

Only a single resin injection point was used foreach half-hull moulding and a long coil spring wasplaced inside the vacuum bag to form a runner tohelp the resin spread the length of the hull. Theinfusion of resin into the reinforcement takesapproximately one hour regardless of the size of themoulding.

The hull moulds for the Flaxcat were as used forthe Aeroskimmer and are flatter bottomed than mostcats, this being intended to promote planing. Otherfeatures of the Flaxcat are fairly conventional and itperformed with better consistency than the morespecialist speed sailing boats to win the prize forfastest boat of the day on more than one occasion.

EMILE LAUTIEREmile is also from the Dutch team led by Niels

Haarbosch. He first told us a bit about their groupand pointed out the advantage of working as a teamto pool ideas and resources. Their team originallyhad nine members. This is now down to four butthe remaining members are true enthusiasts. Inaddition to meeting for sailing trials they meet on aweekly basis to discuss progress. The team generatessome of its funding by doing commercial work suchrepairing fibreglass hulls.

Emile then told us about their kiteboat whichmade brief bursts of speed but in general was slowerat this stage of development than the Flaxcat

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12 CATALYST


described above. This kiteboat is alightweight craft with a comfortableseating position aft in the main hulland a cross beam forward whichcarries two small stabilising floats, andsurface-piercing inclined hydrofoilsmade from aluminium extrusions.There is a horizontal lifting foil atthe bottom of the main rudder, andthis carries a large proportion ofcraft weight when full foil-borne.

The lines to the propulsion kitelead to controls just ahead of thehelmsman. Various types of kite canbe used. During this Speedweek thecraft was tested foil-borne under tow from a motorboat and also briefly under tow from a kite.

For future development the team are consideringdeveloping an electrically actuated and computercontrolled hydrofoil system, perhaps using movableflaps on fully immersed foils. The flaps might behinged to the fixed part of the foils by rubber hingeswhich could allow a better cross section profile thanconventional hinges.

They are working on the assumption that if sucha system were used for record setting then theelectric power would have to come from the wind,for example by use of a windmill powered generator.Michael Ellison said that the rules about this werestill under consideration and that if the power wereused only for control purposes then it is possible thatbattery power might be acceptable. This would needto be further discussed by the World Speed SailingRecords Committee.

BOB SPAGNOLETTIBob showed us the system he has built for tow

testing small models. A heavy weight falls undergravity to unwind a line off a small drum which ismounted, together with a larger drum, on a freerunning spindle. A line leads from this larger drumto a model craft which is drawn across the water asthe weight falls. An encoder on the spindle isconnected to a computer to determine the velocity ofthe craft throughout each run and the towing forceis determined from the weight and drum diameterstogether with corrections to allow for theacceleration of the model and other moving parts.

The system is suitable for models of around 400mm length and Bob would be willing to test modelsprovided by others.

Bob showed us two models he is currently testing,one representing the under surface of a conventional

sailboard and the other representing a sailboard witha stepped planing hull.

Bob constructed such a sailboard a few years backand achieved a speed of 31 knots, so theseexperiments could provide some interesting results.

BOB DOWNHILLBob, as well as being the organiser for Speed

Week, has been doing further experiments with thecraft he refers to as his ‘garage door’.

We have heard rumours about this for some time,but this year we had a first chance to see a large scalemodel of the real thing. Sure enough it does lookvery much like an ‘up and over’ garage door. It is aheavily constructed 2.4 metre square slab of timberfitted with four small surface piercing inclinedhydrofoils, one at each corner. The hydrofoils arehollow, fabricated from mild steel sheet and with akink about halfway along the length so that theupper part is at a shallower angle to the surface thanthe tip.

The first prototype door was a bit smaller at 1.2msquare and was fitted with a sailboard rig. Bob toldus that a skilled sailboarder did manage to get itgoing after a lot of practice. The larger version whichappeared at this Speedweek is intended only fortowing trials but the available motor boats wereunable to tow it fast enough to get it foil borne. A30hp motor boat would hardly move it but I assumethat this was due to the drag of the heavy raft likestructure, not the hydrofoils themselves.

But not to worry, the next version currently underconstruction will be larger but also very muchlighter. It will be elliptical in plan, made fromaluminium skins on a honeycomb core andmeasuring 25 feet long by 20 feet across. Eventuallyit is intended to sail it with twin side by side rigidwingsails adapted from glider wings.

Chr

is Ev

ans

The Dutch kiteboat being assembled

OCTOBER 2001 13

Design

Quarterline, easy build GRP Yacht hullshapes.

Tom Peat

At present a conventional GRP hull is rarely constructed by an amateur. The need to make aplug, and then a mould, makes one-offs uneconomic and time consuming. The alternatives,female mould or wood core are usually used, but these have their own problems – fairing and coreproblems among them. There may however be a way to produce a solid lay up GRP yacht hullwithout a plug.

The trick, if you can call it that, is to produceone-quarter mould and use this to make all fourquarters of the hull. This may seemcounter-intuitive as all four quartersof a conventional yacht hull aredifferent, although mirror images ofeach other. There are however shapesthat can be used to make a mould,from which all four quarters can bemoulded. The making of a concavemould straight off is more difficultthan shaping a plug. Only a quarterof the mould fairing is needed, so,with care, a reasonable mould can beproduced. This will save money andmaterials. Alternatively, a quarter-hull plug could be produced to makethe mould, if this was preferred.

There is then the business ofjoining these four shapes.

This is not the subject of thisletter, but I am sure this can be done, as I have seensome repairs that virtually do this.

By now you may be saying, “Show me one ofthese shapes”. First I must indulge in a little simplemathematics. This is for convenience and themethod could be used without my kind of maths.

The Power Curves:These are Y = Xa (X to the power of a). and are

shown in Fig 1 for X1.2 to X6

These are the curves used in the shapes becausethey are both easy to calculate and relatively easy tomanipulate. The shapes can be easily reproduced,and problems of fairing and calculating offsets arealso simplified.

Shape with some twist. (Axial moulds)Firstly we might consider a mould shape that

obtains a hull form purely by twisting the GRPlaminates. In this first and simplest case the hullwould be made of two longitudinal halves, either byjoining the pieces at the ends while moulding, or byjoining them when both quarters are out of themould. These halves are then given a uniform twistso the bow and stern take on their differing shapes.

This twist should be done with laminates in agreen condition so as not produce too much stress.

The form of such a mould is shown together withits equation in Fig 2.

14 CATALYST

Design

The equation is for thepositive quadrant; theother half of the mould(dotted lines) is just amirror image. Theapproximate section linesfor the hull this mightproduce are also shown inFig 2.

I have made a halfmodel of this to see howthe scheme would work.The mould, Photo 1(below), was constructedof strip planks on plyformers, following thecurves described above.This model mould isabout 1m long to makethe finished model flexrepresentatively.

The mould strips were coveredwith fibreglass, polished smoothand prepared for moulding.

The centre hull section curvewas placed one frame from theend of the mould. The secondcurve from the centre wasproduced twice and the mould made one framelonger than needed. This makes the correct curve inthe strip plank and gives alignment for “in-mouldjoining” of the sections. See Fig 3.

A half-model was produced from the mould; thisis shown in Photos 2 and 3 (opposite). This half hull

has been twisted through about 20 degrees from bowto amidships.

A tetrahedral section was added to make the pointof the bow, this could be added at the time ofmoulding, as, in this case, it is almost a flat plane.

The transom shape has been changed with a littletensioning. If a more pronouncedturn is needed at the transom theparts could be laid up with athinner area on the turn. Fig 4.

This is a fairly narrow hull butcould be made broader by alteringthe equation slightly, however thisshape is not ideal for a moderntype of yacht.

Non-axial mouldingA second approach is to

produce a mould shape that willproduce the quarters of a yachthull without twisting.

Again we will describe thiswith the power curves. A possiblemould shape and equation andthe section lines of the resultinghull are shown in Fig 5. The bow

OCTOBER 2001 15

Design

flare angle has been chosen here to make the deadriseclose to zero at the transom. There are sectionsshown on the mould diagram; these areapproximately the sections of the boat. Each of thesesections has its centreline and a notional deck levelwaterline. Some tumblehome is shown. This is not aproblem in this type of moulding, and could be usedto make more efficient use of the mould area.

This hull does not need twisting, but makes muchless use of the whole mould for the four individualquarters. This shape looks much more like aconventional yacht, and could be adjusted as desiredfor beam/length ratio and shear line.

The advantage of using this shape is that theinternal framing could be added while the hullquarter is still in the mould.

Further ideasThe methods described above can be combined.

Using both asymmetric mould coverage and twist inthe hull, a variety of different shapes can be made.

Computer solid modelling programmes might beconfigurable to generate such moulds for any shapeof boat, but some of these moulds may be almost asbig as a conventional mould, producing noeconomic advantage.

It is a good idea to produce models of anyproposed hulls as this is a good test of concept, andgives an indication of what may be encounteredbuilding a full size boat.

The method is not limited to the production ofGRP hulls. Pressed steel hulls made from a singlesmaller component may be possible, and concretehulls might be produced with a single flexiblequarter-hull mould.

There may even be an application for makingplugs for GRP moulds. I suspect that something likethis already happens in some instances.

The methods described have a kindof square symmetry (90-degreerotation); but other schemes can bebased on hexagonal symmetry.

I can envisage similar schemes thatuse from three to twelve identical curvedsections; however most of these wouldinvolve too many joints to bemanageable. I believe that my four-section “Quarterline” scheme isprobably the right balance for GRPconstruction.

Tom PeatCaithness, Scotland.

[email protected]

16 CATALYST

Design

This boat has already undergone preliminarytests on the River Deben, UK, and has proved

to be an interesting concept. Bystanderswatched in amazement as it sailed across thewater them surmounted a low mud bank andproceeded to sail across that also. Not its main

function in life, but it would make a greatfun boat!

The wheeled yacht now lives at Alton Water,Ipswich and has sailed twice. 1st sailing wasquite windy , Force 3-4, and it performed

well. The 2nd sailing, at which these pictureswere taken, was calm, Force 1-2.

OCTOBER 2001 17

Design

The wheels rotate, slowly, and it isincredibly stable. It is also very

comfortable as you lie down inside it,out of the wind with a headrest and thetiller and mainsheet at chin level. Theupwind performance is staggering as ithas very good grip on the water and so

stable. The pictures show it with itssmall sail: 7.24 sqm including the mastarea. I have not used the bigger DN ice

yacht sail yet as the centre of effortdisplacement it causes make it very hard

to tack.

18 CATALYST

Events

�Winds of Change... how it was for me.�Chris Evans

[email protected]

Having attended the inaugural Winds of Change last year I was delighted to learn that Boband Genevieve ( Bobgen) Quinton had made arrangements with The Royal Harwich Yacht Clubto stage another event this year. A double booking of club facilities called for a slight change indates but that was sorted out early in the year and caused no hardship. This is my story of theevent.

Once into August my thoughts turned topreparing for this event that would be held fromFriday August 17 through to Sunday the 19thAugust. I planned to take my newly acquired(purchased at last year’s Weymouth Speedweek)Foiler 21 “Boomerang” which I had refitted over thewinter months and my outboard powered inflatable.Up to this time I had not been able to sail Boomerangand was looking forward to doing so though Iwished I had been able to check everything on thewater and see that it really did work instead of theliterally dry run in front of my garage/workshop,much to the interest of my neighbours. With this inmind I was careful to make sure that I packed everything I could possibly need in case something wasnot quite right.

I live in the south of Germany, close to thebirthplace of Einstein, Ulm. Which is about 700miles from the Royal Harwich. My mode oftransport is a large (by European standards)American camper which being 9 meters long andtowing a trailer of 8 meters was only just inside legallimits. Not the most wieldy of vehicles but certainlycomfortable and I believe it was Confucius who said“The only thing that mankind really needs is‘Luaus”.

With so far to travel it was obvious that it wouldnot be for just a weekend visit and so I planned for a

two-week holiday accompanied by my wife Gabi.Departing on Thursday morning, we arrived at theRoyal Harwich in time for lunch on Friday, followedby a well-earned snooze to recuperate from theweariness of travelling.

That evening we were joined by our friends andorganizers, Bob and Genevieve to have supper in theyacht club. The club is set in a magnificent area onthe river Orwell. On the landward side of theclubhouse there are tall mature trees which protect itfrom westerly winds and with it’s long drive downthrough well kept grazing land from the smallcountry road, it has an air of grandeur that befits aclub that originated with royal patronage whenKings and Princes enjoyed racing huge yachts backin the 1800’s. Hence the title the ‘Royal’ HarwichYacht Club.

The present clubhouse looks as if it was built inthe 70’s and has been lovingly maintained. Thefloors are polished hardwood and walls are decoratedwith trophies in glass cases and various yacht flags ofhistorical interest. There is a large bar and adjoiningit is a smaller room used as a restaurant and‘function room’ when required. Both rooms havelarge floor to ceiling windows that look out over theclubs neatly mowed lawn with outside seating andtables, onto the Orwell river and its many mooringsthat line the dredged channel. The river is tidal and

The River Orwell at low tide . . .

OCTOBER 2001 19

Winds of Change

the difference between high water and low water isdramatic. At high water the water seems to stretchacross for about a mile but this vast expanse rapidlydwindles when the tide goes out to leave a deep-water channel only 1/8th the size of the former.

As far as our activities were concerned this wouldbe no hardship because high water would occurabout midday for the duration of our stay. Thiswould give us large expanses of water deep enoughfor the type of boats we would be sailing.

The following day Gabi and I assembled andprepared our two boats. One is an inflatable with a15 h.p. outboard motor that pushes it along rathersmartly. This I use to monitor test runs with ourhigh-speed sailer “Triton Chariot” and to be close byin case assistance is needed. The second boat is“Boomerang”, a boat I bought last year because itneeded renovation and is a particularly interestingdesign that was too far advanced for its commercialgood, consequently only half a dozen or so were evermade, and as far as I know this is one of the last twoin existence. It is a striking design rather like atrimaran, but instead of hulls on extendedoutriggers, this boat has a pair of foils - one eachside - canted at about 40° which provide all thestability required with minimal water resistance.Consequently they are quite speedy especially inlight winds.

With both boats assembled it was time for a testsail with Boomerang. This was the first time I sailedthis boat though I have seen it sailing at some of theSpeed trials I have attended. I had made somemodifications and was keen to put them to the test.One modification was to make it possible to steerwith the feet via foot pedals. I have this feature on acouple of my boats and it is worth another crewmember without the weight because it allows thehelmsperson to operate lines with both hands yetstill maintain steerage with the feet. This, of course,means that one sits IN the boat rather than theconventional style of sitting out or ON the boat. Iwas able to incorporate my conversion so that Iretained the original tiller steering and would be able

to choose whichever style I preferred.The weather was fine and sunny with a perfect

breeze for the occasion so Gabi accompanied me onthis maiden voyage. The smile on Gabi’s face saideverything as we slipped effortlessly through thewater. Crews on other boats beckoned to theircompanions who were below decks to come up andsee this strange boat that was overtaking soeffortlessly. Thumbs were raised in silent approval aswe passed them by with hardly a ripple from ourslim boat and it’s even slimmer foils. There would bethe inevitable slight increase of wind speed andBoomerang would immediately respond with a surgeof increased speed that would create a small wave atthe stern which gurgled as if Boomerang waschuckling with joy to be back in it’s true elementonce more.

We sailed to the next village, Pinmill, and thenturned back because it was clear that someadjustments to the lines that controlled the setting ofthe fore sail needed some adjustment. Back at theclubhouse our friends, Bob and Gen joked about thesheer joy shown on Gabi’s face as we sailed away, andGabi rejoined with the affirmation that ‘This boatwe will keep!’

The next couple of days just drifted by withoutanything spectacular. On Tuesday afternoon PhilipMiddleton arrived with Triton Chariot and westarted to assemble it but needed most of thefollowing day to have it ready for sailing. We set offtogether with Gabi and myself in Boomerang andPhilip in Triton. The wind was stronger this day andby the time we reached the open banked regionbelow Pinmill it was blowing a stiff breeze thatdemanded all my concentration and provided someexciting sailing.

As we sped along I heard a clunk on the port sideand looked over to see what it was. It took me acouple of minutes to realise that the portside staythat holds the mast up was streaming uselesslyastern. My first thoughts were that it had brokenbut it was later revealed that a securing pin had comeundone and the stay had fallen down. My heart

. . . and its hazards!

20 CATALYST

Events

stiffened with that awful realization that one stoodbefore a precipice.... something like pressing on thebrake pedal only to have it sink to the floor. OK, youhaven’t hit anything yet... but it’s just a matter oftime.

I quickly realized that as long as we stayed on thistack the wind would hold the mast up but if weallowed the boat to turn and the wind came behindthe sail the whole rig would come crashing down.My initial gasp and cry of shock had startled Gabiinto a state of extreme agitation. Now, I spoke mythoughts aloud for her to grasp the facts and how Iintended to handle the situation. Getting the saildown was out of the question because the pressure ofthe wind would be toogreat; anyway, weneeded that to keep themast up. Gabi triedsome suggestions but Icut her off sharplysaying I had to think...bless her heart she didnot take it badly. Theriver bank was mostlymuddy and soft so itwould not be a problemjust to drive up onto thebeach... This we decidedto do and I swappedplaces with Gabi toallow her to steer so thatI could jump into thewater as we approachedand take some of thespeed off the boat toavoid hitting the banktoo hard. As Gabi tookover the helm I warnedher not to allow thewind to back the sailwhich she immediately started to do but corrected itvery quickly as my voice rose to a crescendo....

I yanked up the centreboard just before leapinginto the water and successfully slowed Boomerangand slewed it onto the thick ooze of mud. The windpromptly pushed the boat further onto the mudwhich made me worry that we might become highand dry because the tide was falling; however, aquick inspection showed that the problem was only amissing securing pin, and I was able to rig up atemporary solution using the foresail halyard. Oncethis was done we could adjust the mainsail to relievethe winds pressure and then turn the boat and slideit off the mud bank. Needless to say the mud was

inky black and everything, including ourselves,looked quite a mess, but at least we were sailingagain; albeit with a ‘Jury Rig’ whose strength wassomewhat dubious. Consequently I sailed with greatcaution and sacrificed speed by spilling the wind asmuch as possible in order to arrive back in one piece,which I am relieved to say that we did. Back at theclubhouse it was straightforward to lower the mastand put matters to rights with some additional safetywires to avoid a recurrence.

Gabi was rather unnerved with all this andconfided with me that she had always assumedsailing to be a serene pastime; clearly that was not sowhen sailing with me.... I understood what she

meant but could notresist reminding herthat at the end of theday we had arrivedhome safe and sound.

Later that evening,about 6 o’clock,Philip and I preparedfor some sailing withTriton. Just as we setoff from the slipway Iremarked to Philipthat there were someominous black cloudson the horizon...shortly after that wewere subjected to analmighty squall thathad us sailing at fullspeed in a flurry ofspray and rain thatalmost blinded me onthe helm. Philip wasworking the trapezeand I shoutedthrough the wind to

him that I could see very little and he should warnme of any obstacles ahead as we blasted through thespray. He shouted back an acknowledgment.

We had fitted the foils but they were hoisted upabove deck out of use. The wind, however, was sostrong that it blew the leeward foil over the side andit then promptly deployed itself automatically.Bearing in mind that so far we have not had any realsuccess getting the foils to work you can imagine ourjoy when this foil suddenly lifted the hull that wasbeing submerged with the pressure of the wind clearof the water.... It was like magic. Suddenly, Philip,who was on the other hull that was previously beinglifted from the water, was now getting his feet wet!

Boomerang - a Foiler 21

Phot

o: G

abi K

oege

l

OCTOBER 2001 21

Winds of Change

There were some moments for us to give a fewwhoops of delight and then I heard a strangeclunking sound.... About the same instant I realizedthat we were too close to the shoreline and the soundwas from the foil hitting the riverbed; the foil wasripped from its mounting with a resounding clunk!Philip hurriedly recovered the broken foil and lashedit down on the trampoline deck whilst I did my bestto keep the boat under control and spill enoughwind whilst retaining steerage.

Muttering words of consolation and regret wecontinued and then made a turn to come back to theclubhouse. We now deployed the other foil andadjusted the sails and were rewarded to see that foilalso worked.... I fiddledwith the rear foilattached to the rudderand was delighted tofind that it respondedexactly as planned.What a pity we wereone foil less thanrequired.

With mixed feelingsof euphoria and dismaywe made our way backto the slipway andbrought the boatashore for the night.After a hot shower inthe excellent facilitieswe retired to thecamper for a beer andsome food anddiscussed the events.All in all the feeling ofjoy that the foilsactually workedovercame thedisappointment ofbreaking the foil. At least we had another set ofdifferent foils that we could try out over the nextcouple of days.

The next day was bright and sunny, with but littlewind, which ruled out any testing of foils. Wemessed about with some sailing but nothing veryspecial. Being the Friday some other participantsbegan arriving. Some we knew and there was muchchatter and passing on of news. That evening was ajolly time in the clubhouse where most of us alsohad a meal together. One of the arrivals was a chapcalled Patrick who owned the other Foiler 21 likemine. We had been in touch with email and I hadchallenged him to a series of races; the winner being

the best of three. He heartily accepted and wearranged to have the first race on Saturday morningimmediately after the days briefing which followedthe excellent ‘Full English Breakfast’ that was all partof the entry fee.

The course was set from in front of the clubhouseand sailing up to a large road bridge and rounding aparticular buoy named ‘Pond Ooze’ and finishing infront of the clubhouse. We started with the winddirectly from behind which is about the slowestpoint of sailing and the last of the flood tide pushingus in the right direction. Patrick headed straight forthe buoy and I took the more radical decision totack across the wind in order to make more speed,

the disadvantagethough is that one hasto travel a largerdistance. I certainlywas making more speedbut after tacking againand then closing onPatrick there was hardlyanything between us...Patrick then foundmore wind and edgedahead of me by aboutsix boat lengths. I triedeverything I knew butonly managed to stophim getting any furtherahead.

At the buoy Patrickturned before me andnow had the wind onthe ‘nose’. This wouldmake some interestingsailing being muchfaster and requiringmany ‘tacks’ that needto be executed

efficiently to minimize time lost with thismanoeuvre. He sheeted in his sails and his craftleaned over with the increased pressure from thewind. The lee foil bit deeper into the water and hisspeed increased, rapidly enlarging the gap between usgiving me the dejected feeling of being left waybehind.

But my turn to round the buoy came and I toowas soon speeding up and in hot pursuit of Patrickin “Speedbird”. I quickly learned that I was able topoint higher up into the wind than Patrick’sSpeedbird. This gave me a choice to travel a shorterdistance, or cover him and travel the same distancebut at a faster speed. For the first tack I decided to

Speedbird

22 CATALYST

Events

point higher to keep clear of him and then, onceahead, I went for speed. I was amazed how muchquicker Boomerang was than Speedbird. It wasobvious that I had made some modifications like arotating mast and a deeper centreboard and thatthese things undoubtedly give an advantage, but itwas the degree of difference that surprised me. Aftercrossing the line I noted the time and waited forSpeedbird to cross some 18½ minutes later.Considering the race took me about 60 minutes youcan see that Boomerang was significantly faster.

Needless to say I was delighted with my victoryand showed little mercy towards Patrick when helater came ashore, especially because, when asked byan interested bystanderwhich of the two boatswas his, he replied“The fastest one!”

We agreed to makethe second race thefollowing morning,Sunday. The rest of thatday was taken up withtimed runs over ameasured distance toestablish the fastestboat of the day. Withonly six boatscompeting there wasnot a lot ofcompetition but Ithought it worthnoting that Boomerangturned in a better speedthan did Speedbird. Imanaged third fastesttime against a very fastcatamaran sporting ahuge sail area, whichcame second. Philiptook top honors with Triton and it being a boat ofmy design was like taking first for myself.

That evening we had an official dinner and therewere a couple of speakers afterwards explaining theirdesigns and demonstrating models they had broughtalong.

Sunday dawned not so sunny but bright and witha lot of wind. Patrick and I soon had our boats inthe water and hurriedly prepared them for thesecond race. Patrick sailed off the slipway before meand by the time I was ready and had sailed out intothe main channel for the start he was way over onthe mud flats which were at this state of high tidecovered with water and perfect for sailing fast. Eager

to commence the race I set off to join him and makethe start together. On my way I had to make someadjustments to the steering and my seat and in theprocess ended up close to a large old sailing boatwith a long bowsprit protruding from its bows, tiedup to a mooring. I judged that I could sail past itbut this turned out to be an error and the port stay -the same one that had come adrift earlier in the week- fouled the bowsprit and scraped along it.Unfortunately there was a tang of metal protrudingfrom the side at the tip and this duly snagged themast stay and held it fast which caused Boomerang toneatly pirouette around the front of the large boatwhereupon the wind was now behind me and sent

Boomerang promptlydown the other side ofthe sailing boat withthe bowsprit stillpoking between themast stay and the mastresulting in“Checkmate” in onemove. Or to put itanother way — “Getout of that!”

For the first minuteI just cursed my luckbut as that did little toimprove the situation Idecided to clamber outon the crossbeams andtry to wrestle the boatclear. It did not budge,which was notsurprising with the tidestill flooding andholding Boomerangagainst the sailing boat,and a fair stiff breezeagainst the mainsail.

Which also made it impossible to get the mainsaildown. Clearly I needed assistance, and lookedaround for Patrick to go and ask for a rescue boat.Patrick was way off playing at fast sailing, and camenowhere near me. I looked ashore but I was quite away off and on the hidden side of the larger sailingboat so not very visible. Fortunately I had someemergency flares with me, and I then sent a whiteflare up. There did not appear to be any action at theclub so I sent another and a minute later another.There was still no sign of action so I then popped offa red flare. This was getting serious because a redflare could set the whole emergency service inoperation including helicopters.... Still nothing, so I

Also there – Gordon Stanger-Leathes‘s Trifoiler

OCTOBER 2001 23

Winds of Change

fired another red flare. Shortly after that I spied arescue boat speeding in my direction.

The rescue boat was only crewed by one personand that made matters difficult but after twoattempts we managed to extricate Boomerangwithout any damage. Getting the towline free againwas difficult and by the time I had done so I wasclose to another boat on a mooring (There are manymoorings on this stretch of river.) Fortunately it hadno bowsprit and I was able to sail around the frontof it but in doing so the large mooring buoy jammedbetween the tiller and the boat snagging firmly,stopping Boomerang in its tracks. I managed towriggle it free with what appeared to be just a benttiller for damage. Now I was in clear water andsettled down to join up with Patrick and start thesecond race.

Sheeting in the sails the boat picked up speed andthen suddenly slowed dramatically as if brakes hadbeen applied. There was an accompanying whooshof water and I looked behind to see a great sheet ofwater shooting up from the back of the boat.Examination showed that the top rudder pintle hadbeen loosened by the snagging with the buoy andnow parted completely, allowing the rudder to whiparound at right angle to the boat and effectivelyapply the brake. I managed to wrestle the rudder freewith some considerable effort and then used the

paddle - normally used to get back ashore when thewind dies - to steer with. I did think I would beable to steer the boat back to the slipway; but withall the moorings around me and with defectivesteering, I decided to ask Patrick who was now closeby, to ask for assistance. Whilst he was doing that, Imanaged to get the sails down in preparation for atow back to shore.

This put the second race completely out of thepicture which was really a shame, but that’s sailing.I’m not too sure if Patrick was relieved orsaddened.... All this excitement had its effect on meand I was happy to take it fairly easy for the rest ofthe day. Philip did manage to convince me to joinhim on Triton to test a couple of the other foils butwith the stronger winds it made steering uncertainand with all the moored boats we decided to call it aday.

The Monday was bright and sunny and we madean early start packing up the boats and loading thetrailers. This was done by midday and I was able togrill some steaks for a Brunch. We needed anothercouple of hours to get away but it all worked outwell enough to avoid the London rush hour andarrive in Dover for the ferry with ample time. Therest of our journey was straightforward and wearrived home on Wednesday morning in time forbreakfast.

Bob & Gen talking to John Thurston

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24 CATALYST

Speedsailing

From Hulls to Boards,Now Foils and Planing

Richard Boehmer

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Hyperwind Sailing = FOEHN NUMBER > 1

Barney Kenney

Before the ink dried on the patent, Windsurfers were impressing sailors with their speed. Shortlythereafter the entire yachting world was astounded when a sailboard became the fastest windpowered craft ever to sail on the water. Since speed under sail has been a quest since beforerecorded history, the significance of this event cannot be overstated. The question now is, howfast can a sailboard ultimately go on the water?

This diagram probably speaks for itself. It does though show that the sailboards seem to have hit a plateau - a matterthat is explored in the article below. Maybe the time for planing craft is coming.

OCTOBER 2001 25

Speedsailing

Perhaps the best way to answer this question is toexamine what causes the drag that holds a sailboardback. A performance analysis of two idealizedsailboards is described that may help to determinean upper limit to board speed on the water.

The simplest sailboard capable of yielding usefulinformation is an iceboard (Fig. 1). With littlestructure and almost no friction on the frozensurface, iceboards have been clocked exceedingFoehn 3 in light winds. (The Foehn number isdefined as the ratio of the board speed to the truespeed of the wind - in analogy with the Machnumber of supersonic flight.) But why can't aniceboard go faster?

In part, the answer is you! The performanceanalysis shows that the biggest drag preventing highspeed is the dragproduced by thesailor standing onthe board - muchlarger than the dragof the board or theparasitic andinduced drag of thesail itself. Even so,with no tipping orskidding constraintsand no constraintsother than drag,Foehn 4.7 istheoretically possibleon an iceboard witha 20 knot wind (Fig.2).

In practice,however, Foehn 4.7has never beenreached. If drag isnot setting the upperlimit for speed, itmust be inadequatethrust. Although imparting many desirablehandling characteristics to a sailboard, the analysisshows that the hand-held sail actually limits themaximum available thrust because the catapultingmoment of the sail (lift times height of centre ofeffort) must be balanced by the hiking moment(sailor’s weight times distance of their centre ofgravity from board). Not surprising to speed sailors,who have taken to wearing 20 kilos of lead on theirback, the hiking moment is a very seriousconstraint, effectively limiting the speed that a 80kilo iceboarder can actually achieve to less than

Foehn 2.3 in a 20 knot wind. Moreover, thesituation deteriorates as the true wind increases.With a 40 knot wind, the maximum speed islimited to about Foehn 1.7.

The course sailed to reach maximum speed onice is also changed by the hiking constraint. In highwinds, maximum speed occurs on a very broadreach, 150 degrees off the wind. In contrast, withno hiking constraint, maximum speed occurs on a105 degree course.

But what about the ultimate speed on water?The iceboard is a useful model because it allows

the performance of the sailor and the sail to beanalyzed in isolation from water effects. Thissimple model establishes an upper limit to themaximum speed that can be reached with a hand-

held sail. On water, asailboard has toovercome additionaldrag from the fin aswell as skin friction,pressure drag, wavedrag and induceddrag on the board.

Historically, theempirical approach tospeed sailing has beentowards smaller andsmaller boards in anattempt to reduceskin friction drag.Although thisapproach has workedwell in the past, thepoint of diminishingreturns may havealready been reached.As the board sizedecreases, the trimangle and the pressuredrag increases. Once

the pressure drag begins to dominate the totaldrag, there is no benefit to continued sizereduction. In theory, minimum board drag occurswhen the skin friction drag and the pressure dragare equal. Keeping the pressure drag as small aspossible also has another advantage because thewave making drag is simultaneously minimized forfully planing boards.

Induced drag is the drag component due to thehydrodynamic lift. It may also be thought of asdrag associated with three dimensional flow overthe planing surface. To minimize the induced drag,

Figure 1. Hyperwind sailing on ice and snow:Jibing at Foehn 2.

Phot

o by

Bla

ke M

ills

26 CATALYST

Speedsailing

the aspect ratio of the planing surface must bemaximized to maintain as much two dimensionalflow as possible. This criterion calls for a transomstern with a large beam and short planing length.Many of the new light wind planing boards meetthis criterion.

Fin drag is the least important factor limitinghigh speeds on the water, partly because today's finsare so good. What is required is a fin with lowprofile drag and a high aspect ratio (length/chord)to minimize induced drag. Almost any high qualityfin of the correct size will do.

A detailed performance analysis using data froma prototype speed board shows that drag on thewater can be reduced from conventional designs.Results for two wind speeds are shown in Fig. 3.Foehn 1.5 is obtainable on the water in a 40 knotwind. Note, at higher speeds, the differencebetween the ice and water boards decreases because

the single largest component of drag remains thesailor. While some drag reduction is possible usingspecial clothing, only minor improvements can beexpected without restricting movement required tosail the board.

To conclude, it is still possible for a sailboard tobreak the existing world speed sailing record of46.52 knots, but it had better be done soon, beforethe record gets much higher. A well designedcatamaran or proa variant will eventually prevailbecause the double constraints of high body dragand restricted hiking moment will be difficult toovercome for board speeds much over 60 knots. Andthen, there are the problems of stability and control,life and death, etc.

Barney Kenney, Ph.D.831 Costigan Court

Saskatoon, Saskatchewan, [email protected]

August 1999

Figure 3. Comparison of the performance of aniceboard to that of a sailboard on water at two

different wind speeds. The wind is blowing from rightto left. The top half of the graph shows results for 40

knot wind, the bottom half for 30 knot wind.

Figure 2. Performance polar calculated for an iceboard(oooo) with an 80 kilogram sailor at two different

wind speeds. The wind is blowing from right to left.Because performance polars are symmetrical about thewind direction only half is shown for each wind speed.

The top half of the graph shows results for 20 knotwind, the bottom half for 10 knots. The theoretical

performance of the same iceboard, if unconstrained bythe hiking moment (****), is substantially higher at

both wind speeds. In this case, drag on the sailor is themain factor limiting speed.

OCTOBER 2001 27

News &Views

Speedweek -Accomodation etc

I drove down on theWednesday afternoon (three hoursfrom work in Horsham W.Sussex).In the gathering dusk, as I droveover the causeway to Portland, the7m para-glider surfers were amagnificent sight: though alas Ihad no camera.

When I got to the sailing centreI heard from John Perry that ChrisEvan’s yellow trimaran had aspectacular grounding. John wascrewing sitting aft, and thought hewas going to be falling a long wayas she cartwheeled forward.Fortunately she fell backwards,having not quite reached vertical.Presumably Chris thought his boatwas amphibious.

Stayed overnight in PortlandYouth Hostel. New at thebegining of 2001. Excellent beds,though too short for me beingover six foot tall. Can sleep 32people in the hostel. Being justoutside the sailing centre I wouldhave thought it would be the bestplace for people to stay duringSpeed Week. The warden ‘Bonnie’,local to the area,did not knowanything about Speed Week orAYRS. Something for the PRofficer to address in Weymouthperhaps?

I passed on the details of howto arrange a group booking nextyear with Bob Downhill (theorganiser of Speedweek for the lastten years). One person makes thebooking paying £13.00 and isgiven a booking number. Eachperson signs into the hostel givingthe booking number and paystheir bed-night fee. (Next year thiswill be £11.25 per night). Theadvantage of a group booking is

that only the person making thegroup booking need be a memberof the YHA, none of the others do.

Excellent breakfast on Thursdaymorning in the Breakwater hotel’sbig blue-glazed tile frontedbuilding in Castletown, 5minswalk from both the Hostel and theSailing Centre. A non-residentFull English breakfast cost £3.50(fruit juice, cereal, tea/coffee, egg/bacon/sausage/fried.bread/mushroom/black pudding, andtoast jam/marmalade) – too muchfor me.

I was a bit disappointedThursday morning that no onewas out sailing, as I had to be backat work on Thursday afternoon.

I eyed the shattered bows of theyellow small float trimaran duringthe morning. Apparently built of3mm ply. I would love to knowfrom Chris (a) How much theoriginally built tri weighed(without rig)? So I can comparefor reasonableness with my Tri’sestimate lightship weight. (b)When I finally move house I willget proper construction drawingsdrawn for my trimaran. WouldChris Evans be interested inbuilding my trimaran for me?Alternatively some other clubmember might?

Watched Slade Penoyretinkering with his hapa designs fora while. Suggestion: Rather thanhaving the drag of a trailingrudder to steer it deeper in thewater, perhaps Slade could trytwisting one of the sailing boardwinglets up on one side relative tothe other. Would it not then bankdownwards to one side? To sail onthe other tack replace it withanother mirror image hapa.

Left Portland at 1115hr. Eighthours later got to Horsham.Never did do any work that day. I

probably lost a good three hoursdriving the wrong way along A35from Dorchester towards Exeter.Turned around at Bridport,though had by then sat in twotraffic jams for road works. I hadtold myself the view was differentbecause I was returning in daylightand besides 95% ot the things oneworries about never happen, sowhy check the map.

My work colleagues say theymight buy me a compass forChristmas. Sat Nav would bebetter as I’ve already proven I candrive around in circles with acompass.

Mark R. Tingley<[email protected]>

Your Letters

Alacrity PlansHello, I hope you can help me.

I am looking for plans for a 19foot Alacrity sailing boat. I havehad no success in finding anythingif any of your members can help itwould be gratefully appreciated.

M Ranson3a East StreetIsle of Wight

England PO33 1JB

ProSurf 3New Wave Systems, Inc.

announces the release of ProSurf3, a major new version of its hulldesign and fairing program. After15 years of development, ProSurf3 has evolved into a general-purpose trimmed NURB surfacemodeling program. ProSurf 3offers unique features, such asusing edit points that lie on theNURB curves and surfaces,dynamic curvature feedback forfairing, fine tune shaping

28 CATALYST

Your Letters

commands, dynamic geometryconstraints, editing and shelling ofpolysurfaces, plate developmentand expansion, hydrostatics,stability and resistance calculationsand a database of airfoil shapes.

“Over the years, our boat andship design program has evolvedinto one that can handle any 3-dimensional shape,” says StephenHollister, President of New WaveSystems, Inc. “We wrote all of thecode in ProSurf 3. It does not useany third party software or kerneland it contains unique capabilitiesthat cannot easily be duplicated.We are also being very aggressiveabout lowering the price ofProSurf 3 to $795. No othersurface modeling programprovides the same capabilities atanywhere near that price. We alsohave a new ProBasic 3 program at$395 and a new ProChine 3program at $195.”

Two of the greatest strengths ofProSurf 3 are its detailed surface

shaping and fairing tools and itsdynamic geometric constraints.After generating surfaces usingsweeping, extruding, shelling,lofting, and other techniques, thedesigner can perform detailedshaping and fairing using fine tunemove commands and dynamiccurvature feedback information.Combined with the use of editpoints that lie on the NURBsurface, these commands provideunmatched, detailed shape controlrequired to develop fair surfaces.The designer can also dynamicallydisplay any plane-surface orsurface-surface intersection whilechanging the shape of the surface.

ProSurf 3 also provides anumber of optional geometricconstraints that can be applied tothe geometry. One of the mostimportant is the ability to “bond”two surfaces together edge-to-edge. This allows designers to editand shape connected polysurfaceswithout having them come apart.

These constraints are optional andare defined independently fromthe geometric entities, whichmeans that they can be added ordeleted at any time withoutaffecting the shape of thegeometry. Another constraintallows the designer to attach acurve to a surface and use it totrim the shape of the surface.Once defined, the trim curve orthe underlying surface can beedited, dynamically showing thechanges to the trimmed surface.No untrimming and retrimming isrequired.

Full descriptions, articles, helpfiles, examples, and ademonstration version of ProSurf3 are now available atwww.newavesys.com.

Stephen M. Hollister,Jamestown, Rhode Island, USA

Tel: (401) 423-1852email: [email protected]

A Boat Building DayA day of discussion on boat-

building theory and poracticewill be held in the ThorpeVillage Hall (between Stainesand Chertsey, Surrey, UK) onSunday 17th February 2002from 9.30am to 5pm. (Followthe signs towards Thorpe Parkthen enter the village.)

Bring your project along, orif you cannot bring it, bringsome pictures (OHP or 35mmslides for preference) and beprepared to talk about it!

Details from Fred Ball, tel:+44 1344 843690; [email protected]

OCTOBER 2001 29

Notes from Toad Hill

A Solar Panel Experiment

Frank Bailey

Solar panels are probably becoming more common as time goes on. The A.Y.R.S. has publishedarticles on solar powered electric boats. The following material was assembled by me who up tothis point knew very little about solar panel capabilities, their characteristics, limitations, andgenerally, their care and use. My electrical expertise is extremely limited but I can glue woodpretty well. After fiddling around with a panel as described below, I still feel I have a long way togo in understanding solar panels and how and why they work.

I had need of a solar panel for two reasons. First,the Toad Hill Boat Shop Annex has no electrical powerand I wanted to install a radio for entertainmentwithout continually purchasing small dry cells while Iscrape and paint, etc., listening to Benjamin Britten’s“Sea Interludes” perhaps. The second reason was Iwanted to keep a battery charged so that I couldmaintain a 12 volt source for a weather station with

instruments at the mast head of my small sailboat, theLulu Queen, which only uses a 40 Plus Seagulloutboard without a generator.

The panel I purchased was advertised as a solarbattery charger for marine, RV and automotivebatteries. The stated characteristics of the panel, whichcost about £65, are as follows:

Rated Power 5.0 WattsVoltage maximum power 16.5 voltsCurrent maximum power 0.3 amperesVoltage open 23.8 voltsCurrent Short Circuit 0.37 amperesNominal area 0.8 Sq. Ft.Weight 1.2 lbsCost per Sq. foot £8.13

For convenience I built a simple wooden mount tohold the panel in a sundial type arrangement for mylatitude. See Figure 1, including a small sketch of asundial. I assume you are all familiar with horizontalsundials, and that the style of the gnomon is sloped tomatch the users latitude (What the heck is a gnomon?)Additionally, I allowed the panel to rotate to followthe sun as it passed from East to West. As it turnedout, this additional mechanism probably wasunnecessary. For the short duration of the tests, whichonly took several days time around noon, all of thismay sound like overkill. Note there are eleven segmentsthat make up the panel. Different experiments weregone through to see if I could determine what was inthe “black box”, or panel.

Experiment 1. No sketch is associated with thisexperiment as initially I was afraid of blowing up myammeter and voltmeter and perhaps even overloadingthe panel but got up enough courage to attach thepanel to two 12 volt automobile light bulbs in series.The readings were 4.5 volts and 1.0 amp across bothbulbs, the amperes being about three times the rated.Since R=E/I, the ohms were 4.5. There was only a

30 CATALYST


very dim glow to the bulb signifying not muchcurrent capacity was generated for the bulbs so I triedone bulb and got 2.5 volts and 1.05 amps, givingabout 2.4 ohms and not much more brilliance.Nothing smoked so I proceeded to the next experiment.

Experiment 2. I thought it wise to find the curveof voltage versus current when various resistanceswere in the circuit. This curve is shown in Figure 2.The curve is similar to another panel curve I haveseen, that is, as the current increases, the voltagedrops. The various resistances I used are shownalongside the curve. Several things may be noted here.With the resistances I used, the current developed iswell beyond the maximum power current listed in theoriginal specs. Since D.C. watts is the product ofamps x volts, where the horizontal and vertical linesmeet on the curve, the area of the resulting rectanglerepresents the watts generated. The area shownrepresents about 12.6 Watts which is much more than

the rated of 5 Watts (16.5 Volts x 0.3 Amps. = 5Watts.) I was now worried about blowing out thepanel. I did not understand why I could generatemore Watts than the rated output other than the factthat I could have initially added more resistance tothe circuit and thus reduced the current flow. I thinkthe main thing to note at this point is that therelationship I=E/R does not work here. (There is apoint on the curve that will give you maximum Watts.You calculus experts may wish to find this point onthe curve in relation to the slope of the tangent to thecurve, scale factors, squares and rectangles, etc — aninteresting problem.) The variable resistance used wasa length of nichrome resistance wire marked off on aboard with feet and ohms. After looking at the results,I should have used more resistance in the circuit formore readings at lesser currents.

Experiment 3. All experiments were carried onunder a clear sky, whatever that is. NorthernMichigan skies are clearer than western Pennsylvaniaskies for instance. I was interested in how the voltsgenerated related to the angle of orientation of thepanel to the sun. Generally the experiments wereconducted around about local noon so the panelwould be sloped to the rays in a North/Southdirection because of latitude but otherwise the panelwas in a more-or-less horizontal position in the East/West direction. Figure 3 shows the results. It appearsthere was very little change in voltage until the panelwas almost edge on to the sun’s rays. I don’tunderstand this but it appears if the sun merely hitsthe panel, it works! This will give you some idea ofhow to mount your panel on your boat. This candepend on your course sometimes but on the otherhand, why not just mount it on the deck (where you canwalk on it)? Most mountings appear to hang from a rail.

Experiment 4. Courage up, I now put a 12 voltradio in the circuit using two setups, as shown inFigures 4 and 5. Setup 1 (Fig 4) has a resistance inseries with the radio. Typical data for this Setup 1 is:0.6 amps, 9.5 volts with 20 ohms in the resistance. Ifthe resistance was too high, there was not enoughvoltage left for the radio to work. Note that thevoltmeter is across the radio only. Typical data forSetup 2 data is: 0.85 amps, 8.0 volts, 0.50 ohms. Thereason for the resistances in the circuits is I was afraidthe voltage generated by the panel would be too muchfor the 12 volt radio. In each setup I changed theresistance until the radio worked. There were of courseranges of resistance where the radio still worked. I nowhad sound in the Toad Hill Boat Shop Annex withouta battery, as long as the sun was out. I did not connectthe radio to the solar panel without any resistance inthe circuit. No guts - but see next experiment.

OCTOBER 2001 31


Experiment 5. No sketch. Inow hitched up a 12V car batteryto the car radio, watching carefullythe polarities. The radio worked.(Why not?) The radio/batterycombination drew 0.7 amps with10 volts on the voltmeter. Why thevoltmeter did not read 12 volts Idon’t understand. I then added thesolar panel. With the solar panelconnected, readings were aboutthe same. This assembly was nowmost useful as I could have theradio on in the Annex aftersundown.

Experiment 6. No sketch. I hadon hand a 12 volt battery needingcharging badly. It read on the meter only 5 volts. Ihitched up the panel to the battery to see if I couldrecharge the battery. Some electronic items will keep abattery charged but will not re-charge a depleted one.To maintain some kind of standard sunshine, I onlykept the solar panel connected to the battery betweenthe hours of 10AM to 3PM. It took about nine hoursto fully charge the battery.

Experiment 7. No sketch. You will note from thesketch of the panel mount that the panel itselfconsists of 11 sections. I covered each section withheavy cardboard held in place with tape. I thenrandomly uncovered one panel at a time to see howthe open circuit voltage changed. It was no bigsurprise to see that the voltage increased in straightline proportion as each of the cardboards wereremoved. Is it possible to glean from this informationthat the panels are arranged in a parallel assembly? Tofurther test this assumption, I took a piece of heavycardboard sufficient to cover all panels at once andexposed the panels vertically one inch at a time untilall 6½” of the panel width was uncovered. There wasnot much voltage difference from start to finish. With1” uncovered, the voltmeter registered about 15 voltswhich rapidly increased to full voltage when thepanels were fully uncovered. Did we learn anythinghere worthwhile?

The experiments are now done. I feel a bit moreconfident in the use of my panel. The panel itself isstill a black box to me but I can use it now withoutdestroying it or my radio or meters I think. It is stilluncertain if I have damaged the panel by drawingabout three times the rated current from it. I mayhave shortened its life perhaps. Is it possible some ofyou readers have additional worthwhile experiences,good or bad, with the care and feeding of solar panels?

Those not particularly interested in celestialnavigation need not peruse the following material.But I assume many of you are true sailors who cannavigate by the sun, stars, moon, and planets.

Please refer to the sketch showing a representation ofthe earth in January and July. You will note the axis ofthe earth is tilted either away or toward the sun’s rays.The object of this exercise is to try and determine howmuch further the sun‘s rays have to go through ouratmosphere and become more or less attenuated as theseasons change, compared to a place on the earth wherethe sun is directly overhead at noon. It is granted thatvery small particulate matter locally located is probablymore important than the total distance the rays travelthrough our atmosphere. Nevertheless, it is aninteresting exercise in geometry to try and figure thisproblem out. It is a bit more difficult I believe to solvethis problem for a sunrise and sunset condition as youhave to work in a three dimensional world.

If we assume the earth’s radius is 4000 miles, and theatmosphere is 100 miles deep, to use round numbers,and it is noon, we can then solve a fairly simplegeometric problem. The solution lies in finding thechords of a circle. Developing the formulas andrunning through the calculations, it appears the sun’srays have to traverse about three times the distance ifthe sun is not directly overhead at noon and you are inthe latitude of London (51ºN) in January. Obviouslythe best possible conditions for most sunlight is to sailin an area and time when the sun is directly overhead atnoon to get the maximum power conversion from yourpanel. None of the above experiments have involvedany kind of cloudy or hazy day or say a day in LosAngeles or Calcutta.

Two more experiments were undertaken: The solarpanel has zero output in full moonlight. In fullsunlight, the panel reached a temperature of 125º F.

32 CATALYST

Catalyst Calendar

This is a free listing of eventsorganised by AYRS and others. Pleasesend details of events for possibleinclusion by post to Catalyst, BCMAYRS, London WC1N 3XX, UK, oremail [email protected]

November

6th AYRS London meetingSubject to be announced. 19.30for 20.00hrs at the LondonCorinthian Sailing Club, UpperMall, London W6. Contact:AYRS Secretary, BCM AYRS,London WC1N 3XX, UK; tel:+44 (1727) 862 268; email:[email protected]

December

4th Proas: a panel discussion(Participants include: MorrisArthur, Simon Fishwick, IainHutchinson, Richard Smith,Charles Sutherland, KeithWebster, etc )19.30 for 20.00hrs at the LondonCorinthian Sailing Club, UpperMall, London W6. Contact:AYRS Secretary, BCM AYRS,London WC1N 3XX;tel: +44 (1727) 862 268; email:[email protected]

January 2002

3rd - 13th London InternationalBoat ShowEarls Court Exhibition Hall.Those who can, from 16thDecember onwards, give a day ortwo to help build/staff the AYRSstand (reward - free entry!)should contact Sheila Fishwicktel: +44 (1727) 862 268; email:[email protected]

January

12th AYRS Annual General Meeting19.30 for 20.00hrs at the LondonCorinthian Sailing Club, UpperMall, London W6. Contact:AYRS Secretary, BCM AYRS,London WC1N 3XX; tel: +44(1727) 862 268; email:[email protected]

February


17th Boat Building Day9.30am to 5pm in the ThorpeVillage Hall, Coldharbour Lane,Thorpe, Surrey ( off the A320between Staines and Chertsey –follow signs to Thorpe Park, thento the village). Bring your projectalong, or if you cannot bring it,bring some pictures (OHP or35mm slides for preference) andbe prepared to talk about it!Details from Fred Ball,tel: +44 1344 843690; [email protected]

March


April

2nd AYRS London meetingSubject to be announced. 19.30for 20.00hrs at the LondonCorinthian Sailing Club, UpperMall, London W6. Contact:AYRS Secretary, BCM AYRS,London WC1N 3XX, UK; tel:+44 (1727) 862 268; email:[email protected]

Catalyst �a person or thing acting as a stimulusin bringing about or hastening a result

On the Horizon . . .Electric Propulsion Design � Theo SchmidtProa Foil Sections � Tom SpeerThe Maximum Speed of Yachts � Bob DillAlerion Electric Auxiliary Conversion � Charles HoughtonKCat70 �a High Performance Motor Sailer � G CoombsMore Sunshine � Chris EvansMore sources and resources: reviews, publications and

Internet sites

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

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