Best length for 3 layer veneer fiberglass covered monohull

Discussion in 'Boat Design' started by pironiero, Aug 6, 2020.

  1. fallguy
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    fallguy Senior Member

    I have a 1960 cold molded 16' Carver and it has no guts save a keel, but the bottom is about 5/8". No glass, sure, but not at all the same class of boat for speeds or conditions. The boat is rated for 45 horsepower!

    I'd like to know if anyone has built a cold moulded offshore racer.
     
  2. gonzo
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    gonzo Senior Member

    There are thousands. I have raced cold molded boats extensively. Frers, among others, was building laminated hulls for offshore racing 70 years ago.
     
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  3. fallguy
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    fallguy Senior Member

    Any real big ones? There must be some common knowledge on hull thicknesses.
     
  4. gonzo
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    gonzo Senior Member

    I raced and cruised a 36' in the late 70's. Four of them were built and all are still sailing. The hull was 12mm honduras mahogany with stringers about every 16". They also have four bulkheads and structural bunks/cabinets.
     
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  5. fallguy
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    fallguy Senior Member

    Sailboats with lower hull speeds, right?
     
  6. Ilan Voyager
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    Ilan Voyager Senior Member

    In Russia you had excellent pine and birch plywoods largely of marine quality even if not marked as. Probably you could find a good suitable plywood and look for a good plan suitable for you.
    Cold molded wood is very tedious and uses a lot of epoxy resin, plus sanding and sanding and sanding again. You should think over a hard chine, or some more curvy alternatives. There are several methods, all feasible by an amateur.
    For voyaging boats plywood hard chine has advantages, it's cheaper, easier to build with minimal tooling and hundreds of gluing, stapling and sanding hours are saved. Pretty easy to repair.
     
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  7. gonzo
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    gonzo Senior Member

    It would plane at probably 15 kt or so.
     
  8. fastsailing
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    fastsailing Senior Member

    Pine, birch and also spruce. The latter having least density, and thus most thickness for a given weight. Several species of wood could also be combined easily for the same plate if constructing out from several thin plywood layers. Heaviest density closest to the surface. Another advantage of spruce over pine is that branches are significantly smaller, leaving smaller structural voids to the plywood ie more uniform structural properties.
     

  9. fastsailing
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    fastsailing Senior Member

    Then don't use hull plating made of plywood as supporting structure for the keel as in boats with bolt on keels on solid fiberglass laminate. Plywood will not be suitable for that practice no matter how thick it locally might be. Use a proper internal support structure to transmit and spread out all the keel related loads to a very large area of the rest of the hull made out of plywood even when it is coated with grp.
     
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