Skin On Frame Catamaran

Discussion in 'Boat Design' started by ElGringo, Sep 14, 2016.

  1. ElGringo
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    ElGringo Senior Member

    Has anyone built a skin on frame catamaran? Or maybe a part S.O.F.? Hulls Only? Anything? Just curious, got bored and was watching YouTube and the thought came to mind.
     
  2. Petros
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    Petros Senior Member

    I have built skin on frame trimaran, and a skin on frame prowa competed in the Race to Alaska last year.

    I have been thinking of a skin on frame catamaran for a number of years (I have built perhpas 15 skin on frame kayaks, and 8 or 9 skin on frame small sailing tris and dingys).

    No reason why it would not work. what would be kind of fun is a folding skin on frame catamaran. I have built several folding kayaks, it is about three times more work to build, and adds a lot of weight and cost, so I am reluctant to try it. though a skin on frame catamaran is in my future some time...I have to try it sooner or later.

    I have also been toying with the idea of a 16 ft skin on frame folding pocket cruiser. enough room for short overnight trips in a small cabin, but can be dismantled to fit in three or four large duffle bags. I could not think of good design that would be fast to assemble, so the market might be limited for such a craft.
     
  3. rasorinc
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    rasorinc Senior Member

    1 person likes this.
  4. ElGringo
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    ElGringo Senior Member

    rasorinc, Thanks for the link. That's a bit different alright. Looks like it works and probably didn't cost a lot.

    Petros, If it can be done it would sure cut the cost and time by a huge amount. I think you could still do hard chines if your design called for it by using strips of about four inches wide to form the chines in place of the plywood sheets and fiberglassing them before you skinned it.
     
  5. Petros
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    Petros Senior Member

    I have no idea what you are talking about here, traditional skin on frame is fabric (cotton, nylon, or polyester) with some kind of sealant, saves the cost of fiberglass. I find working with fiberglass unpleasant and costly, building traditional skin on frame means no costly materials, no toxic compounds, and can all be built with hand tools.

    I can build a 16 ft skin on frame kayak for about $100, so a sailing catamaran would cost perhaps about $300. If you used fiberglass on it you are talking about three times the cost. Less if I can located suitable salvaged lumber to remill.

    There is a type of construction used on larger boats called skin on frame which uses thin plywood panels over a frame, and than it gets fiberglassed over the outside. This is not traditional skin on frame if the "skin" is fiberglassed plywood panels.
     
  6. upchurchmr
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    upchurchmr Senior Member

    There was a SOF take a part catamaran built by Folbot.
    This was some time ago when they were in Europe.
    Recently there was a video of one sailing, with the claim that there were 3 still existing.

    You might search for it.
     
  7. ElGringo
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    ElGringo Senior Member

    There is a type of construction used on larger boats called skin on frame which uses thin plywood panels over a frame, and than it gets fiberglassed over the outside. This is not traditional skin on frame if the "skin" is fiberglassed plywood panels.[/QUOTE]

    That's the kind I'm talking about. The shape of the hull usually has sharp angles when compared to the more round shape that is used on skin on frame kayaks. instead of using plywood to cover the whole section as a panel. Use narrow strips of plywood along the angle shape and glass the inside of it. Leave the rest of the area open and cover it with fabric. The strips of plywood would add strength to the wood stringer that is normally running the length of the hull in the area of the angle shape. Of course there are others but one is almost always in the angle. The bulkhead shape would have to be modified for the plywood strips to lay in the same way the stringers are.

    If I have really got you mixed up, I'll try to sketch it.
     
  8. Manfred.pech
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    Manfred.pech Senior Member

  9. ElGringo
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    ElGringo Senior Member

    Manfred, That is more like what I was thinking. Do you happen to know how well it worked? Do you think it would work with hulls shaped more like Richard Woods Skoota 28? Not as large as his but of the same shape?
     
  10. Manfred.pech
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    Manfred.pech Senior Member

    Yes it worked and it is still alife -- as far as I know.

    But if you want a SKOOTA - build or buy one. It is better on all points. I have built more than 35 boats, but I' ve learned that it is better and cheaper to buy a new or used one or at least a shell. But if you like to build .. OK. Nobody will give you back the time you are building and not sailing. Now at the end of the season it is the best time to buy a used one.
     
  11. ElGringo
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    ElGringo Senior Member

    Manfred, I used it as an example of the hull shapes because I would want two small outboards mounted on the hulls. I don't want to sail, just motor around lakes and rivers.

    The idea is even more interesting since Petros gave his estimate of the cost. I think if the cost was 3 or 4 times what his estimate is, it would still be a bargain and a fast build
     
  12. Nnnnnnnn
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    Nnnnnnnn Junior Member

    Something like that?

    [​IMG]

    It's German „Scalare 250“

    http://www.faltbootbasteln.de/fbb-faltkatamaran-scalare.html
     
  13. upchurchmr
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    upchurchmr Senior Member

    El Gringo,

    I've built 5 SOF (fabric on a frame) kayaks and never come close to Petros's cost.
    Think more like 3-5X that for a kayak.
    Better think 10X or more for a catamaran. Building the hulls doesn't include the crossbeams and the deck, and reinforcement of the sterns for the motors. Nor especially the cost of the motors, controls, and seats.

    If you are going to have something with plywood completely enclosing the wood frame there is no reason for a fabric skin.
    But there is a real good reason for glass/ epoxy on the outside. Wood only is easily damaged when beaching the boat.
     
  14. ElGringo
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    ElGringo Senior Member

    Upchurch, I have no idea what the materials would cost, if you lived where Petros does, there is plenty of wood. Here in the Texas Panhandle, I was probably 14 years old before I saw the first tree that was not planted and carefully watered by someone. It might be cheap there.

    Anyway, on to the subject. I was not saying cover the frame with plywood and then cover it with cloth. Just use plywood strips to add strength and stiffness to the chine area's. I have made a sketch and since I am sure everyone will want an autographed copy, I will make them available for only $29.95 signed, numbered, and dated by the Great El Gringo, designer of catamarans extraordinaire.
     

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  15. upchurchmr
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    upchurchmr Senior Member

    I get it now. Thanks.

    Good luck with the autograph thing.

    Given the amount of effort involved with the ply strips, you might be just as well off with solid ply.

    You might also want to think about a flat bottomed boat. It will not decrease the performance much and would be vastly simpler to build.

    Good luck.
     
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