Vacuum infusion Male vs Female

Discussion in 'Sailboats' started by pironiero, Oct 20, 2020.

?

Which one

  1. Female mould

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  2. Male mould

    0 vote(s)
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  1. pironiero
    Joined: Apr 2020
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    pironiero Junior Member

    Hello guys, I'm arguing with my father at the moment, what's better for making 1 sailboat hull I'm on the side of making a female mould like shown here fist link, second link, third link, polishing it and applying gelcoat, fiberglass, foam and other stuff, this way i will get rid of chores of sanding the hull and applying gelcoat by hand.

    and my father is on the other side, he thinks that its better to make a male mould with wood, then cover it with foam and fiberglass, then sand it and apply gelcoat. His main argument is that sanding the hull is much and much easier than the mould.

    Which way is better given the fact that maximum of 2 people will be doing the work and this is a 10m boat?
    In both ways vacuum infusion will be used.
     
  2. DCockey
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    DCockey Senior Member

    Convex surfaces are much easier to fair/smooth than concave surfaces.
     
  3. Blueknarr
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    Blueknarr Senior Member

    I've been involved with building several foam over plug projects. It is easier and faster for a one-time thing than perfecting a female mould.

    Why gelcoat? LPU paint put performs gelcoat and will be easier to apply.
     
  4. fallguy
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    fallguy Senior Member

    Personally, I think you are both a bit wrong.

    A female walk in jig is almost a joy to build in. Polishing it for gc for a single release; no way.

    Once done, flip it over and gc or paint the outside like you would a male.

    advantage is the internal bulkheads and even the deck can be fitted before flipping..the trouble with your dad's idea is the removal of the framework can affect the hull shape and the effort to avoid is more work

    So both part right and both part wrong. If you were going to pop a hundred boats out; female.

    one boat; walk in jig mould, infuse the inside, bh, flip, infuse outside skin and male work the finish
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    So what is this boat, a monohull, or a cat, or ? The making of a female mould is big bucks and lots of work, unless there is wonderful simplicity to the hull shape (unlikely), and male moulding has its problems, and still ends up being a lot of work, I am wondering if you have considered something like C-Flex construction. I don't know why you would want infusion even, unless there is some weight sensitivity issue, but the actual boat to be built, is not shown.
     
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  6. pironiero
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    pironiero Junior Member

    We are in monohull section.
    Have you checked the links in top post?
    too heavy
    There is no need to show a boat, yes, there is a weight factor, I'm going to race it.
     
  7. Mr Efficiency
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    Mr Efficiency Senior Member

    I checked the links, and of course it was a cat ! Though obviously not what you are building. If it has compound curvatures, I would say male mould is the only way, otherwise a mountain of work. You do need to make a cradle to receive the hull once pulled from the male mould, but that isn't that onerous.
     
  8. Rumars
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    Rumars Senior Member

    A raceboat is not supposed to have any excess weight, so no amount of fairing compound is acceptable. This means female mold. The boat is also supposed to be perfectly fair and that is almost impossible to do for some shapes without using a male plug first.
    If you think a female mold is less sanding, you are wrong, it's just that you sand the mold or the plug and not the boat.
     
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  9. Mr Efficiency
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    Mr Efficiency Senior Member

    A female mold made from sheet material would certainly be less sanding, but one assumes this thing is all compound curves.
     
  10. messabout
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    messabout Senior Member

    Building with something like Ocumee ply will cost less, weigh less and , be quicker to build. That method is also not as itchy or as smelly as fiberglass building.
     
  11. pironiero
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    pironiero Junior Member

    Not in Russia
     
  12. Mr Efficiency
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    Mr Efficiency Senior Member

    What about local supplies, plenty of wood in Russia, just yesterday I was watching a doco about the Yak planes during the war, and how they contained wooden spars and skins, which did the job splendidly.
     
  13. pironiero
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    pironiero Junior Member

    It is heavier than foam+glass i assume
     
  14. messabout
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    messabout Senior Member

    Foam plus glass is an attractive way to build if weight is the criteria. But only for small boats. Foam/ glass works well enough for dingy builds if they are small, three or four meters. For a boat of 10 meters length, the glass content must necessarily be rather thick, thus heavy. For a boat of that size you can build in ply and maintain sufficient strength while minimizing weight. Glass over foam is also rather labor intensive except in cases like a paddleboard where the body if the boat is solid foam and glass is applied only to the exterior.

    If you are determined to use glass then the female mold will make a slick boat. Problem is that the female mold will force you to build a plug on which to cast the female mold. What the hell, if you have to make a perfectly accurate and fair plug, then why not just build the boat of wood the exact same way you'd have to build the plug. If you are to have a male mould then you still have to build the plug. Very well then..................If you intend to make many boats from the mold, then the work and expense is worth it. If you intend to make only one, maybe two boats, the whole mold idea is an exercise in self flagellation.
     

  15. pironiero
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    pironiero Junior Member

    The problem is-wood is hydroscopic, it may be fine for a warm country, but not for Russia, my father's boat was cold moulded with fb over several layers of strip planking, in a span of winter it gains around 200-300 kilos, i kinda doubt that its that much but even its half-it's quite substantial for 11m boat.
     
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