How hard is it to make a mould of a hull?

Discussion in 'Boatbuilding' started by SpiritWolf15x, May 13, 2014.

  1. SpiritWolf15x
    Joined: Apr 2010
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    Location: Vancouver, Canada

    SpiritWolf15x Senior Member

    Just wondering as to how hard it would be to make a mould of a pre existing hull. I have a wood sailing dinghy that I am tired of fixing and rebuilding it in foam and glass or just straight glass is looking very appealing.

  2. Yobarnacle
    Joined: Nov 2011
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    Location: Mexico, Florida

    Yobarnacle Senior Member holding true course

    Would it matter if the new boat was a quarter inch bigger n all dimensions?
    If that's acceptable, wrap your dinghy in multiple layers of saran wrap or similar product and glass over it, using it as a plug mold.
    6 to 8 layers of glass should be strong enough.
    Drill a few quarter inch holes in your dinghy before wrapping.
    A high pressure air source (air gun) applied to these holes will help pop the cured casting loose.
    Some folks might suggest waxing and polishing and a release agent.
    Plastic film is quicker and peels off the inside of the new hull easily.
    Use vinyl electricians tape for areas needing strapping.
    Anything stretchy will release from the fiberglass, unless it gets embedded inside the glass. Try to avoid that. :)
  3. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    That depends on several things, the first that comes to mind is whether it is an "open" shape that won't resist withdrawal from a mould, the way a dovetail locks in to its joint. But typically you will finish up with a heavy boat in GRP single skin compared to the wooden one, and not so stiff either. Sandwich would fix that, but not so easy to build. Time you prepare the existing boat to make it suitable to take a mould off it, create the mould, then build the boat, fixing your existing boat may seem an easier task !
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