foam score board bonding

Discussion in 'Boatbuilding' started by gtflash, Apr 13, 2012.

  1. gtflash
    Joined: Jun 2006
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    gtflash Senior Member

    Repairing a damaged hull and core, and have removed all bulk heads and core to outer skin. I am going to use a foam score board, but am questioning how to bond it to outer core.

    I planned to use and epoxy resin, with a filler, to bond to outer skin, and then overlay the extra 2 layers of bi-axial and epoxy resin

    Boat is a 8.5m powerboat originally laid in derakane.
     
  2. gtflash
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    gtflash Senior Member

    ps this core is running surface
     
  3. waikikin
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    waikikin Senior Member

    Hi gtflash'
    google up an installation guide from diab on core bedding & adapt the hand lay instructions to your epoxy glue mix, basically you need a continuous bondline & to completely fill all the contour cuts with the mix esp in a boat bottom, very importantly use a V notched applicator(typically 4mm/sometimes 6mm but leaning to about 2.5-3) & ALWAYS resin prime your gluing surface of the foam. Do some tests on some waxed glass to test your quantities & results & on a rougher substrate allow some extra material. Jeff.
    PS the install instructions are often packed into the boxes of foam too but easyish to find online.
     
  4. gtflash
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    gtflash Senior Member

    thanks for feedback. West systems talk of replacing a core and give instructions for balsa as pasted below. I have not found DIAB specific instructions yet. West systems say to use low density filler, but I am sure I read not too on this forum??



    The first step was to brush neat (unfilled) WEST SYSTEM® 105/206 over the entire bonding surface inside the opening. This was necessary because even after sanding, the surface remained somewhat irregular because of the chopped strand fiberglass used to build both the upper and lower deck skins. The neat epoxy flows to better fill this fairly level but uneven surface. The next step was to thicken 105/206 with 407 Low-Density Filler to a consistency slightly thicker than mayonnaise. With an 809 Notched Spreader, a small amount of this "core bedding" mixture was applied around the edges of the repair against the existing core; more was spread out over the neat, uncured epoxy already brushed on the area. The core was then draped over a 10" diameter PVC tube. Then core bedding mixture was applied in the cuts between the blocks as they opened, both in the 0° and 90° directions, when the tube was rolled. Then the filled core was fit in place and compressed down, squeezing out any excess bedding mixture. Finally, the repair area was cleaned up, all excess bedding mixture was removed, and any voids or gaps were filled using a squeegee, taking care to maintain the 12:1 bevel (below). A layer of release fabric was placed over the repair and worked down with a squeegee, and everything was allowed to cure completely.
     
  5. waikikin
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    waikikin Senior Member

  6. rwatson
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    rwatson Senior Member

  7. waikikin
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    waikikin Senior Member

    I'd open that pail & check it out, if it stirs up & cures on test you might use it for some thing non critical or temporary, also uncured resin products turn into a disposal issue, for example if I take pails with sticky residue to the tip they wont take em, if I brush some catalyzed resin into them & fill em with shop waste no problem. Jeff.
     
  8. Herman
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    Herman Senior Member

    2 things might have happened:

    -1. It went hard and lumpy. In that case catalyse, set out in the garden, after cure and cooling down, discard.

    -2. Stuff is still ok (might have a puddle of resin on top, remix). Geltime has drift away from what it was supposed to be. Do a test, and use without problems.

    generally no. 2 is the case.
     
  9. rwatson
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    rwatson Senior Member

    The idea of actually using it is appealing to me - I was told that it had a shelf life of only 12 months, so I just didnt even bother even looking after the first 18 months.

    I should at least take the lid off I suppose.
     

  10. yachtie
    Joined: Mar 2012
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    yachtie Junior Member

    I've used epoxy left on the shelf for about ten years and it was ok. I bet yours is still alright. Don't open it unless you are ready to use it
     
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