Literature about making a female mould

Discussion in 'Fiberglass and Composite Boat Building' started by pironiero, Mar 8, 2021.

  1. guzzis3
    Joined: Nov 2009
    Posts: 660
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    Location: Brisbane

    guzzis3 Senior Member

    As said above this is routine. Round bilge sailboats are often made this way.

    You model the hull take section at suitable intervals along the length add an allowance for the stringers, cut them out of whatever's cheap.

    You can get mdf/chipboard/ply/etc packing sheets for almost nothing. You don't need good faces just structural integrity.

    Next you strip plank it. Depending on the hull shape the strips can be anything from 1/2" wide to 4' for areas without double curvature. Use whatever you can get cheap.

    Now you have a 3D female form. Line it with something to stop your resin keying into it. Vacuum bagging film has some stretch, or any number of painted finishes.

    Make sure you use a good release agent before you do your layup.

    If you are shorthanded consider infusion. Supplies are cheap from Utek and possibly others. A cheap refridgeration vacuum pump off ebay (or 2 if you are nervous about breakdowns). Take your time setting up and getting it airtight and the infusion is relatively simple.

    Jigsaw panels are fine if you happen to have a cnc router but it's a lot of work by hand and doesn't enhance the process much. Strips of really cheap timber and a nail gun gives you more freedom for shapes and is pretty quick.

    As mentioned above sealing everything against moisture changes is a good idea.

    There is TONS or information about on infusion and mold making. Make something small to get acquainted first. Good luck :D
     
  2. pironiero
    Joined: Apr 2020
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    Location: saint-petersburg, Russia

    pironiero Senior Member

    but how to make it airtight for infusion?
    Can you share some links please?
    yeah, planning to make a dinghy this way this spring\summer
     
  3. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    The mould doesn't need to be airtight for a single sde infusion in a female. The core can be made airtight and tested airtight before glass is even laid.

    After the skins are applied, the hull is given bulkheads and structural rigidity and then flipped and the exterior also infused against the core surface. Bottom faired, perhaps painted even. Flipped back to finish.

    Now, I have not done it, but it can't be done both sides; simply too risky and difficult. Furthermore. The hull is cradled; you can't glass the cradle side.

    For a two sided infusion; yes, airtight. But not the whole hull bottom. If they do it; that would be pretty wicked cool. But I have not seen it. Remember, something that big gets walked in to lay foam.

    Sorry if I sound patronizing. It is late and I am tired.
     
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  4. guzzis3
    Joined: Nov 2009
    Posts: 660
    Likes: 104, Points: 43, Legacy Rep: 42
    Location: Brisbane

    guzzis3 Senior Member

    Airtight:

    As said some people infuse the inside first then the outside. I would rather line the mold in bagging film. Use contact to hold it to the stringers. Or bog the mold to make it airtight then paint it in something shiny so your hull doesn't stick.

    Just search resin infusion. There are innumerable articles and videos. Everyone has their own method. Just try stuff until it works. Start small and simple. Make a hatch lid or something. Make flat panel bulkheads. Do the hull skin last.
     
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