Plywood Wingmast Design, who can design one & has experience?

Discussion in 'Sailboats' started by Franzi.v.B., Feb 17, 2011.

  1. Franzi.v.B.
    Joined: Jan 2011
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    Franzi.v.B. Junior Member

    Hi,

    while I am into boat design, I am clearly not a specialist in designing masts. Especially unstayed rotating wing masts.

    Can anyone point me to a designer who has experience in designing reliable wingmasts of plywood, epoxy and fiberglass suitable for amateur construction?

    The mast in question is appoximately 12m tall.

    How much can I expect to pay for a set of plans suitable to built the mast from?

    You can sent me a personal message if you want.

    Many thanks,

    Franzi
     
  2. tom28571
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    tom28571 Senior Member

    Eric Sponberg, who shows up on this forum has done unstayed wingmasts. Whether he, or anyone, has done unstayed plywood, I don't know.
     
  3. CutOnce

    CutOnce Previous Member

    Don't know about plywood wing masts, but here is a wooden rotating aerodynamic section mast as done by Jan Goudgeon (of West System fame).

    Even basic terminology is debatable in this field. If you are serious, I'd contact Steve Clark (in Rhode Island - he posts here infrequently), as he usually has thoughts about how one can use low tech materials in high tech applications. Most other wing mast folks will have experience only with current state of the art materials.

    Although I encourage your research, I think you may end up looking at higher technology materials after you come full circle. Weight is critical, and foam cored panels from which you can cut wing sections are not hard to fabricate.

    Hope that helps a little.

    --
    CutOnce
     
  4. sawmaster
    Joined: May 2010
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    sawmaster Senior Member

    wigmast construction

    the geougeon brothers from bay city mi,(the west system folks) published some info a few years back about plywood wingmasts they had used on their multihulls--dont remember the length but I seem to recall they Were quite successfull --might be a place to start
     
  5. bruceb
    Joined: Nov 2008
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    bruceb Senior Member

    proven wing mast

    Look up posts by Gary Baigent- he has posted wooden mast designs on the Buc 24 thread and other places, and has actually built and sailed them, not just theory. They are rotating, stayed masts, but very light and fairly simple to build. B
     
  6. Doug Lord
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    Doug Lord Flight Ready

    =====================
    You probably can't beat Eric Sponbergs experience in design. Go to this link and scroll down for an "aero rig" built entirely of wood-no carbon at all: http://www.sponbergyachtdesign.com/Masts.htm
    You can e-mail Eric from his site or here at boatdesign(he is a member as Tom pointed out). Good luck!
     
  7. CutOnce

    CutOnce Previous Member

    I concur about Gary Baigent's designs, but the original poster specified a "wing" mast, not necessarily a rotating aerodynamic wood mast. I guess it all depends on his actual interpretation of wing mast.

    These one or two line requests without enough detail to allow a good answer are always a challenge. Wing mast could mean anything from "not square timber" to the current crop of C Class catamaran wings - and anything in between.

    As for who can design one, anyone can. It would be better to ask who can design one that has a chance of actually delivering substantive benefit. To do so would require a very clear understanding of the platform, the conditions expected, the goals, the budget and the level of failure tolerance.

    Also, specifying the core/structural material up front kind of cripples the designer's ability to produce a product. Budget considerations may have the designer arrive at using ply, but a good designer may also arrive at choosing other core materials where overall objectives including budget are optimized.

    Wing sail experimentation may lend itself to creating "disposable" wings where the builder acknowledges up front that using cheap materials that allow cheap function - while accepting short lifespan and poor damage tolerance. I'm thinking unsealed foam core structure or corrugated plastic packaging may be interesting.

    The critical, most expensive element in a wing is the main spar - usually carbon in high end efforts. If one used a carbon spar and then "disposable" ribs, you may have a functional solution where a crash only damages the "cheap" stuff, but the core investment is retained. Herein lies the engineering and design challenges - optimizing material selection to meet project goals - and forcing project managers to choose realistic goals.

    Not enough detail was provided in the original request to answer any of these questions.

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    CutOnce
     
  8. Gary Baigent
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    Gary Baigent Senior Member

    I'm drawing up plans for a double luff, soft sail, double battened main on a 12 metre tall x 1 m chord x 220mm thick wing spar; the double luff is 170mm wide and the sail 1.5 m, giving me a total of around 28-29 m2 area - this for 7.6m Seditious Sid. I'd post a jpeg but my digital camera has failed. The main spar (roughly half the total sail area) will be 3mm klinki, plus uni carbon, with cut away frames every metre, no I beam, because the chopped off after section becomes the I. With a double luff, I can hide the down facing vang between the sails ... that means no semi circular main sheet track and highly loaded main sheet systems. The big deal is that although the main spar is a metre chord, the boat will be able to live with that on a mooring ... but the full wing, because of the double luff, will be able to be REEFED.
     
  9. Gary Baigent
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    Gary Baigent Senior Member

    Here's an earlier wing mast 15.5m x 500mm, tensioned ply with I beam and carbon reinforcing, can be picked up by one person standing at the mid point balance position, around 75kgs at a guess.
     

    Attached Files:

  10. mojounwin
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    mojounwin Junior Member

    Gary, I'd be interested to hear more about your double luff mast. Will the mast/sail combination be symmetrical or will the sail reverse shape for the opposite tack?

    Cheers
    Mojo
     
  11. Gary Baigent
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    Gary Baigent Senior Member

    Mojo, the main spar is around 45% the total sail area, and that is symmetrical in cross section, looks like a long D with the double luffs set aft of the widest section ... and when the main spar and the end plate spanners are cranked round, the battens on the leeward sail side will bend out - and those on the windward side will bend inwards ... so the trailing soft sail becomes asymmetric and a sweet curve. That's the idea anyway. Also some batten end spectra lines will be set up the spar running inside to base to also tension the windward battens inwards, to give even more asymmetric depth and also to reduce leach fall off. A picture would make it more explainable.
    Jim Young suggested the very clever idea of curved down battens that swivelled on ball joints at tack and clew ... and you pulled lines to swivel them to make the correct asymmetric overall sail shape, sort of like what he did with Fiery Cross's canting keel dogleg mechanism. But I think my idea is simpler and less weighty. He disagrees.
     
  12. mojounwin
    Joined: Dec 2004
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    mojounwin Junior Member

    Thanks Gary. Can you keep us posted how it goes?

    Cheers
    Mojo
     

  13. CutOnce

    CutOnce Previous Member

    I remember seeing a double luff main sail development about ten years ago out of Australia. Two bolt ropes, sliding up twin tracks on a single mast. There was effectively two mainsails that made the mast/sail combo into effectively a wing surface. It was a one or two man performance dinghy project if I recall correctly.

    Your spar above looks quite impressive, especially at the weight quoted. I think this type of development is well suited to multihulls with their less frequent capsize tendency. Weight aloft is less of a problem in cats as well, as it is windward of the only hull in the water up to a point. Any heel on a typical monohull and all that weight is in opposition to righting moment.

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    CutOnce
     
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