Foiler Design

Discussion in 'Sailboats' started by tspeer, Nov 12, 2003.

  1. Doug Lord

    Doug Lord Guest

    Flying 14's

    Alans, I have it on good authority that there will soon be two or three more flying 14's-great for sailing!
  2. alans
    Joined: May 2004
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    Location: Australia

    alans Alan

    I have heard rumours and we may be seeing the birth of a new class of dinghy. Can you help in tracking these potential fliers. I would be pleased to assist them.
  3. Doug Lord

    Doug Lord Guest

    Foiler 14's

    Alans, contact John Ilet at:
    I think there is a lot of interest in flying 14's on foils!
  4. brian eiland
    Joined: Jun 2002
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    Location: St Augustine Fl, Thailand

    brian eiland Senior Member

    Sailing Boat or Sailing Plane

    Thought some on this subject might be interested in this item.

    Is it a sailing boat or a sailing plane?

    Tue, 29 Jun 2004

    'Flying or sailing?' by Stephen Bourn
    American glider pilots call their aircraft sailplanes, emphasising the close affinity between sailing boats and wind powered aircraft.

    Now the links have moved closer as an Australian defence scientist has created the design for a revolutionary sailing craft, based on a wing-borne hydrofoil concept which he believes will break the world sailing speed record.

    Stephen Bourn, a mathematical scientist with the Australia's Adelaide-based Defence Science and Technology Organisation (DSTO), claims his design will allow the sailing craft to travel at more than twice the speed of the wind in which it is sailing.

    Bourn is certainly a 'boffin'. He has a degree with honours in mathematics from the University of Adelaide and is currently completing a PhD in pure and applied maths.

    But he has a few other credentials, he has thirty years of experience in sailing and as a member of Australia's world speed record holding Macquarie Speed Sailing Team, has discovered quite a bit about speed sailing.

    Over ten years ago, the Australian 'Yellow Pages Endeavour' claimed the world speed sailing record. Despite many attempts by craft of all shapes this record remains unbeaten.

    The Australian team, with their next boat 'Macquarie Innovations' failed to break their own 1993 record of 46.52 knots, after two prolonged attempts in 2002. 'Macquarie Innovations' is a rigid sail, extreme purpose built craft and only sails in one direction on a unique flat-water course.

    Bourn explains, 'I decided to take a fresh look at the principles of sailing and the absolute limits to performance. What I came up with was a design that results in a much higher maximum speed.'

    'With sufficient wind and speed the hull will lift completely clear of the water surface, the craft will fly, leaving only the submerged hydrofoil struts cutting the surface.'

    'The air-borne hull means much lower drag. The relative positioning of the wing, hull and hydrofoil is inherently stable and there is no risk of capsize as sail force increases, unlike conventional craft. This allows a much higher power-to-weight ratio, and combined with lower drag, the result is much higher maximum speed.'

    Bourn believes the new design has the potential to shatter the full range of performance expectations set by conventional yachts, skiffs, catamarans, sailboards and kites, and to challenge the outright speed record.

    The initial design is for a sail-craft with an eight-metre wingspan. The craft will fly at a maximum speed exceeding 30 knots whenever the wind exceeds 15 knots. It will sail upwind and downwind faster than the wind.

    'We have proved the new design concept on a number of radio-controlled models. We've also undertaken thorough analysis and computer simulation and are now seeking sponsorship to construct a full size craft,' Bourn stated.

    The craft certainly looks like a cross between an aeroplane and a sailing boat. Picture a catamaran where there is no trampoline, just a beam, and the second hull is much reduced in size. Underneath this smaller second hull is a scythe-like hydrofoil – the only part of the craft that doesn't lift out of the water.

    A single wing-like sail is attached to the central beam or mast that is not central to the boat, but rather sticks out at an angle on the opposite side to the hydrofoil.

    The single hull is where the pilot, oops, helmsman sits controlling the height, speed and direction of the craft by two joysticks.

    'The positioning of the wing, hull and hydrofoil is inherently stable meaning, unlike conventional craft, there is no risk of capsize as the sail force increases,' says the sailor-scientist.

    'It can be launched from the beach and the cloth wing collapses quickly and easily for transport by trailer.'

    As well as creating the next thrill-seeking toy for sailors and kite-surfers, it looks quite radical enough to challenge for the World Speed Record.

    by Rob Kothe of Sail World
  5. mothingmiller
    Joined: Jun 2004
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    Location: Glasgow, Scotland

    mothingmiller New Member


    hey, new to this forum, been reading the threads. it occured to me that the monent arm the forces from the rig is the same if the main liftig hydrofoil is located on the rudder of daggerboard, however the moment arm a canard type lifting surface mounted on the bow changes depending upon where the main lifting hydrofoil is located. The moment are is largest when the main lifting hydrofoil is mounted on the rudder.

    This all means that the canard type height controller should be roughly twice as effective when the hydrofoil is mounted on the rudder.

    what do you guyes think?

    Chris Miller
  6. tspeer
    Joined: Feb 2002
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    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    Yes, but then the canard has to take most of the load. The configuration becomes a forward main foil (the canard) with a stabilizing foil on the rudder.

    It's best to concentrate as much of the load as possible on the foil with the greatest span. Then use the other foil(s) to control that main foil's incidence to maintain the desired height.
  7. markdrela
    Joined: Jun 2004
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    Location: MIT Aero & Astro

    markdrela Senior Member

    On the Decavitator we had a roll/pitch/height control system which worked very well.

    There was a tiny canard with a passive surface sensor at the nose of each of the two hulls. These held the noses a few inches above the water at any speed above 5 knots or so, giving roll stability. The canards carried no load with the design CG location and design prop thrust. The main wing directly under the CG carried all the weight.

    When underway, the boat could pivot in pitch about the hull noses, thus changing the wing's angle of attack. At any given speed, the wing automatically sought a depth such that its angle of attack gave a lift equal to the weight. As the boat accelerated, the wing would gradually rise up. If nothing was done, it would rise all the way to the surface and ventilate.

    That's where the pilot's depth control lever came in. This lever simply changed the wing's incidence angle relative to the boat. But in effect it biased the pitch angle of the boat about the hull noses, and hence controlled the wing depth. This of course added to the piloting workload, but it was quite manageable. When cruising at one speed, there was no need to twiddle with the depth lever.

    Lots more info is at
    Here you can also see photos of the ventilating V-wing.
  8. mothingmiller
    Joined: Jun 2004
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    Location: Glasgow, Scotland

    mothingmiller New Member

    Sorry, didn't quiet make what i ment clear, the sailor would have to move his weight right ot the back of the boat, and it would be benificial for the rudder not to be mounted on a gantry so that the lifting surface is nearly directyl under the sailor. This would result is say 90% of the mass of the boat and sailor on the main foil, and the other 10% on the canard.

    Buy the way i have built some foil section. its molded naca 64412 which i have a set of female moulds for. the layup i used had a few layers of unidirectional carbon around a 1/8 thick sheet of balsa to give some thickness to the layup. it worked really well. theres a more detailed description at the link below.

    My final year project at uni was to design an electronic control system for a bi foiler. I constructed a simulation in matlab which took into accound all the forces generated by the foils, and then applied clasic control theory to the outcome. the report can be found at:

    i recomend that you download the word version as the html one is tedious to read, and for some reason the picturers are messed up.

  9. Steve Clark
    Joined: Jul 2004
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    Location: Narragansett Bay RI

    Steve Clark Charged Particle

    A Class rules allow hydrofoils. But they can't be capable of lifting the boat clear of the water. So Trim foils on the rudders are OK and you can play with the dagger boards to generate some lift, you just cant take off.
    This is an interesting middle ground similar to where the ORMa 60s operate where you enhance sea keeping and reduce drag without actually flying.
    We are playing with a similar concept on a C Class just now, will report when we have some results.
    It took me a while to tune in here.
    Steve Clark
  10. charliemagee
    Joined: Jul 2004
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    Location: Eugene, Oregon, USA

    charliemagee Junior Member

    wand connection?

    Hello All,

    New to the forum and not sure if I should start a new thread because my question is far less technical than what I've been reading here. But I'll throw it out and if you'd prefer that I start a new thread, please let me know.

    I have a Slatts 22 tacking outrigger with a single hydroil on the outrigger hull.

    Foil angle of attack is controlled by a joystick in the cockpit. I'd like the option of a wand controller like on the Rave. But I've never seen a Rave and don't know how the wand controls the cable/foil connection. Can anyone link me to drawings and descriptions of how that functions so I can cobble one together for myself? The more detailed the better of course.

    Sorry if I'm off topic.


  11. Doug Lord

    Doug Lord Guest


    I don't know how much you know about the wand on the Rave so I'll run thru the basics. The wand is a curved "stick" with a flat bottom that drags(actualy it "planes") in the water: at low speed it angles way back pushing down on a flap on the main foil creating takeoff lift as the boat speeds up. As the boat rises the wand is pulled forward and down by a shock cord; the length of the wand and the tension sets altitude. On the Rave each wand(one on each side) is independent so not only does the wand control altitude but stability as well.
    On your boat it sounds like maybe the whole foil moves instead of just a flap as on the Rave. An automatic system producing the same end result as on the Rave would require a system more similar to a Hobie Trifoiler that uses all moving foils activated by "feelers" sticking out in front of the boat. Not as robust a system as the Rave, in my opinion, but definitely works. The good news with the Trifoiler is that it is patented by Greg Ketterman and if you go to the Hobie site you could possibly get the patent number and order a copy of the patent for $5 or less.(good illustrations)
    Either of these systems can develop a whole lot of drag in lite air though the Rave has a "clutch" that allows disengagement of the wand in those conditions.If the wand is not disengaged it pushs the flap down creating max lift at the right speed but at speeds below that it is DRAG....
    Is controling the foil on the Slatts(?) labor intensive? Some foilers in the past have used systems that used shroud tension to change the angle of incidence of a foil. The Monitor which is one of the earliest sailing foilers used such a
    system.A shroud tension system would automatically change from tack to tack allowing the foil angle of incidence to be reversed as you come about. But it would take a lot of experimenting.
    I guess you should probably decide which of the two commercially available systems are best for you and then try to go see the boat up close....
  12. Jon Howes
    Joined: Jun 2004
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    Location: UK

    Jon Howes Insomniac- sleep? Wassat?


    Before this craft gets too much more publicity you may like compare his website with ours. They both have video clips of the vessels in action, draw your own conlcusions...

    Mr Bourn's:




  13. charliemagee
    Joined: Jul 2004
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    Location: Eugene, Oregon, USA

    charliemagee Junior Member

    wand connection?

    Thanks Doug, I figured I'd have to do that sooner or later. I was just hoping someone had sketches of the connections of wand to foil control cable so I can start fiddling.

  14. Doug Lord

    Doug Lord Guest


    Charlie, just one more thing: the wand system on the Rave is a direct pushrod connection not a cable.
    Does the whole foil move on your boat or does it have a flap?

  15. charliemagee
    Joined: Jul 2004
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    Location: Eugene, Oregon, USA

    charliemagee Junior Member


    It's a cable that connects to a push rod. But the connection is inside the housing of the arm that the foil hangs off of and I haven't opened it up yet. I'm sailing the boat almost every day so I don't want to risk losing vital parts in the water. I'm raising these questions in preparation for my winter project of switching from manual (hand) control to automatic (wand) control.

    The whole foil moves. If you have time, the first picture on this webpage might help:

    You can see the red cable going into the top of the armature. At the bottom you can see the rod coming out to attach to the foil.

    Thanks for all your help.

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