Use styrofoam cooler as mold for box seat

Discussion in 'Boat Design' started by anamealreadyinu, Jul 24, 2014.

  1. anamealreadyinu
    Joined: Jul 2014
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    Location: FLorida

    anamealreadyinu Junior Member

    I'd like to build a custom box seat for my J16 skiff. I was planning on building a wood frame and thin plywood and then sealing/encapsulating in fiberglass and epoxy.

    I'd like to make it weigh as little as possible so it occurred to me I might be able to use a Styrofoam cooler to get the shape I want.

    Few questions:

    1.) Using just fiberglass, can this be made strong enough and if so, what type of fiberglass should I use and how much?

    2.) How do you "treat" the styrofoam so the fiberglass will "pop" out or does the styrofoam not adhere to the fiberglass/epoxy?

    3.) As another option, should I just use at least a 1X2 wood frame and sytrofoam sides to shape the sides in fiberglass to give more strength?

    Any additional advice is appreciated as my inexperience with these materials probably leave out a few questions I should ask but don't know.

    Thanks!
     
  2. Skyak
    Joined: Jul 2012
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    Skyak Senior Member

    Making the seat out of solid fiberglass can be done but it will be relatively heavy and costly. A core would cut weight and cost.

    Styrofoam will likely not release from fiberglass and might not even be compatible with resin. Polyethylene plastic sheet is a good release.

    There is foam core that is designed specifically for fiberglass work. I have seen some guys who use cheaper construction foam -ask on the build forum. The way I would do it is make a male mold out of the core, dry fit fiberglass, wet out with epoxy, then use polyethylene sheet over top to get a smooth finish.

    Post dimensions for comments on fiberglass -on the build forum.
     
  3. anamealreadyinu
    Joined: Jul 2014
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    Location: FLorida

    anamealreadyinu Junior Member

    That would work, is there a URL or supplier for the Polyethylene sheet for purchase? I am very new to the materials you are referring. Thanks for the help.
     
  4. Skyak
    Joined: Jul 2012
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    Skyak Senior Member

    All the plastic sheet I have seen in the big hardware stores has been PE and even if it is polypro or PVC it should be OK.

    I am less certain about foam compatibility if not specifically designed as core. Ask the builders.
     

  5. Russ Kaiser
    Joined: Jul 2009
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    Location: Winston-Salem, NC

    Russ Kaiser Exuberant Amateur

    I found the folks at Fiberglass Supply to be very helpful when I was first getting started with fiberglass years ago. I sent them a sketch of what I was trying to build and they told me the best way to go about it.

    http://www.fiberglasssupply.com/

    They sell foam core material for surfboards and other projects. Many times instead of using foam as a mold material that will be removed the foam remains in the finished project (like in a surf board). If you're not already, maybe you should be thinking along those lines. Shape the seat in foam and glass both the inside and outside.
     
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