hull materials

Discussion in 'Boat Design' started by vampiresquirrel, Jun 1, 2011.

  1. vampiresquirrel
    Joined: May 2011
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    Location: orlando, fl.

    vampiresquirrel Junior Member

    I remember reading back before world war 2 several companies were making
    wood aircraft ( lockheed, Timm, deHavalin ect.) by using thin wood sandwitched onto an inside plug - and maybe an outside mold too. I think
    some used a heat curing resin and autoclaved the whole thing. Lockheed
    used concrete for their molds somehow.
    Are there ways to make a plywood inside plug which would have formers
    and plywood skin maybe coated with jell-coat and sanded slick. Then
    start adding long strips of thin wood using epoxy or recorsonal and laminate
    the thing up about 5 layers thick overlapping the joints and crossing the
    grain directions. Would this still be doable for the 15- 25 foot long range?
    Maybe somehow use a vacuum bag to hold the layers down while they cure.

    Just thinking out loud .....
  2. Lurvio
    Joined: Jul 2009
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    Location: Mid of Finland

    Lurvio Mad scientist

    The technique is called cold-molding.

    You could make the hull laminate on station molds, but you'll need framing inside the hull in most cases anyway so laminating over the framing probably makes more sense.

  3. Wynand N
    Joined: Oct 2004
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    Wynand N Retired Steelboatbuilder

    also my personal favorite building material. :cool:
    Beauty with CMP is that you can get all the bulkheads, dividers and most of the furniture installed with the frames before laminating the plywood hull...
  4. messabout
    Joined: Jan 2006
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    messabout Senior Member

    Check out the Gougeon brothers book. Titled appropriately: The Gougeon Brothers On Boat Construction. There is enough information there to keep you off the streets and out of bars for years. Plenty of text, pix, and proven advice about cold molding. The book is worth more than its cost. ....and no I am not connected with these guys in any way except in recognition of their craftsmanship and knowledge.
  5. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Don't pay any attention to Messabout, he's been getting a 20 dollar bill once a month for years, to plug their stuff . . . :p

    In all seriousness, cold molding is a fine way to get a hull, though I find it a bit fiddly for the novice builder. You're much better off building over a male jig, built from station molds and fairly closely spaced stringers (depends on how thick the first veneer is).

    In WW II (and prior) they used resorcinol (phenol) and urea formaldehyde formulations as the adhesives, which replaced the fish guts or mammal milk glues employed until WW I.

    It's a well covered subject with many texts available. Check out the book store here.

    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    "In all seriousness, cold molding is a fine way to get a hull, though I find it a bit fiddly for the novice builder."

    However the advantage for the novice is a piece of hull is fitted one at a time.

    So even tho the piece may be trimmed 5 - 10 times , it will finally fit , so the $crap box stays small.

    In addition with modern epoxies and a good staple gun the amount of hull built at one time can be 15 min or 12 hours , great for the novice!

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