Joining fibreglass beach cat hull.

Discussion in 'Multihulls' started by Pondlife, Dec 19, 2017.

  1. Pondlife
    Joined: Nov 2015
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    Pondlife Junior Member

    Hello all.
    In need of advice. I have an old Hurricane 500 hull that I would like to modify and take a mould from. This will need to be a split mould due to the shape. Originally how would the hull halves been joined together? Taping the inside seam would be difficult to access through round hatches. Would bonding paste alone be strong enough?
    All the best,
    Mark
     
  2. jorgepease
    Joined: Feb 2012
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    jorgepease Senior Member

    Pretty sure that boat is like most, with a bottom mold and a deck mold, they are joined at the hull deck flange. Before they would have been glued and bolted but today possibly just glued.
     
  3. ThomD
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    ThomD Senior Member

    Unless there are very efficient flanges, you need tape. Sometimes you have to cut additional access points that you later patch up. Ideally, the design will have beam and hatch details, etc... that will allow access. There are lots of books on making kayaks that show how to unroll tape inside the hull. Or you can recruit understanding children. Merit badges go a long way.
     
  4. Pondlife
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    Pondlife Junior Member

    It will have a split line running the length, and vertically. A sizeable access hatch will probably be employed. thanks
     
  5. rwatson
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    rwatson Senior Member

    The trick is to get a fair bit of thickness along each side of the keel before joining.

    Make sure that before you pull the side pieces off, that they have quite a bit of "overglassing" past the keel line. When you have the sides off, you will easily see where you need to trim, and it will ensure that you dont have really flimsy layup near the join area.

    There is also a good case to add more glass along each side of the join lines, and trim flush, before attempting the join. If you do some decent preparation, you might get away with just an epoxy glue job, without needing very much "after join" re-inforcing.
     
  6. jorgepease
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    jorgepease Senior Member

    Sorry meant bottom - hull ... and deck, not mold.... or are you saying the boat is joined vertically?
     
  7. Pondlife
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    Pondlife Junior Member

    Thanks for the info. By the side pieces, you mean the portion on the release flange? would you trim up with a stanley when green and then add more thickness to it and retrim before bonding the halves together? Would you use bonding paste with polyester boat? Cheers mark
     
  8. Pondlife
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    Pondlife Junior Member

    Yes it will have a vertical join due to the tumblehome nature of the hull.
     
  9. rwatson
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    rwatson Senior Member

    Inside the mould, along the keel line, will be over the outside release flange, yes. When you layup the half hull, I just realized that the other half may not be there due to access problems, so you could use some kind of temporary "dam wall" around the release flange on the half mold, ( you could use modelling clay, plaster etc) so that you can extend the layup past the actual edge of the hull line, so you can ensure that there is a good thickness where the final join will occur. After initial trimming to shape, yes, I would also build up the final join lines with extra tape and perhaps matt rovings. The thicker the final contact area between the two sides, the better

    "would you trim up with a stanley when green and then add more thickness to it and retrim before bonding the halves together?"
    Yes, that's what I was thinking. You could use a variety of tools, from stanley knife to fine wood saw while green. Even a wood plane. Its amazing how quickly a good straight edge and coarse wet and dry abrasive sheet will true up the join line. Dont forget, if you join with thickened epoxy, any inadvertent gaps are easy to fill.

    "Would you use bonding paste with polyester boat? "
    I have no ideas what bonding paste is. There are plenty of good adhesives eg Sikflex products (which may be what you mean by bonding paste) , but I would be inclined to use epoxy (with a bit of thickening additive like Cabosil ) after curing, to ensure maximum strength and waterproofness, especially as you may need to add internal reinforcing tape later, and this would be best done with epoxy, to suit the material "gluing" the two side pieces together. Laying epoxy soaked tape over a proprietary goo might cause problems.
     
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  10. Pondlife
    Joined: Nov 2015
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    Pondlife Junior Member

    Great information. Thanks!
     
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