Mold Making By Plywood

Discussion in 'Fiberglass and Composite Boat Building' started by pavel915, Oct 21, 2015.

  1. pavel915
    Joined: Nov 2006
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    pavel915 Senior Member

    I am new in fiberglass boat building.

    I need to know if I can use plywood to make the plug for building the mold. If I can use plywood, then what kind of lamination I should use on the plywood surface before start making the mold?

    I want to build a kayak.
     
  2. gonzo
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    gonzo Senior Member

    Are you building one kayak or many?
     
  3. leaky
    Joined: Sep 2008
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    leaky Senior Member

    I'm just a do-it-yourself-er who has pulled off a few projects.. but my go-to mold material is "hardboard" sold at home building materials stores. I could see building a mold out of it for a handful of items but not like 50.

    It's a brown material, with one side porous, and one side shiny.. The stuff is basically a heavy duty cardboard but has one shiny finished surface.

    That shiny side takes real well to being waxed with a release and used as a mold; the stuff is fairly flexible and bends on a consistent radius too (ie unlike plywood that by nature has softer and stiffer spots)..

    Jon
     
  4. wet feet
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    wet feet Senior Member

    Plywood is absolutely fine.It will need sealing and smoothing before it is ready to produce a mould.There are many products that will work.
     
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Jon, the "hardboard" stuff is masonite and not especially durable, particularly in a moist environment.

    You can make a mold out of your aunt Millie's mashed potatoes if you want, so long as you can justify it's durability. Plywood wouldn't be mu first choice, except for station molds. For your needs plywood or MDF station molds with softwood stringers seems the easy, cheap and logical route. The mold will be stiff and easily faired. Is this a round bilge design or hard chine? Some merit can be made, for plywood skin over the station molds, if it's a hard chine design.
     
  6. pavel915
    Joined: Nov 2006
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    pavel915 Senior Member

    My one is a hard chine design. I think I can easily make the shape of the hull by plywood by stitch and glue method along with some stations inside the hull. My question was how should I laminate the surface of the plywood before I go for applying the PVA, gel coats and so on.

     

  7. slneatboat
    Joined: Nov 2003
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    slneatboat Junior Member

    Prime plywood, fill and fair, spray duratec or similar. Rub down with 150 grit dry then spray again, rub down through the grades ,polish, wax ( 6 or 7 coats ) and away you go. If it is not a large plug you may not need to spray twice and you can brush or roller it on. No need for the p v a.
    Lots of work but has to be done! !
     
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