Cleat install in foam build.

Discussion in 'Fiberglass and Composite Boat Building' started by fallguy, Jul 28, 2018.

  1. fallguy
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    fallguy Senior Member

    I need to install ? probably 3 per side ? 8" ss cleats on my 10M cat hull outsides.

    The boat is foam. Is this done with a plywood insert or is a ply backer sufficient? I am laminating with 22 oz triax, but that doesn't seem string enough to me, which rules out a simple backer. Then when you go to tighten it down; would surely delam from core.

    Are these typically done solid glass or inserts or some other way?

    Thanks for any advice. I might be ahead of drawings here; so please don't reference the designer.

    Just the standard methods of installing cleats on foam builds.

    Thanks much!
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    I'm sure you will be told solid inserts, but if the thing is already all laid up where they are going to be installed, a widish backing plate on both sides should be able to withstand any reasonable load. Obviously the preference would be for something that is durable, even a thickish piece of solid glass laminate, with rounded corners, would do. But not too small, obviously.
     
  3. fallguy
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    fallguy Senior Member

    I am ahead of the game; the core is not done.
     
  4. Blueknarr
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    Blueknarr Senior Member

    As Mr E say solid insert.
    Style of insert dependent on expected load. Extreme loads (winches. travelers dock cleats) might include G10 /aluminum/stainless surface plates over similar core insert plus extra cloth. A blog of fairing compound might suffice for low load canvas snaps.

    All hardware attachment points will eventually need solid cores. Better to do during build than as repair. Usually at most inopportune moment.
     
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  5. fallguy
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    fallguy Senior Member

    Like this?

    Solid glass would be 12mm?

    Call it a music festival quality sketch!

    454D233F-4D44-4F0C-AED6-1A73220988F0.png
     
  6. fallguy
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    fallguy Senior Member

    Then how big a ss (teehee) backing plate for 8" cleat and how thick a plate. All metal other than the beams on the boat is 316.
     
  7. fallguy
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    fallguy Senior Member


    I understand overboring and solid core for most stuff, but things like bow eyes and cleats and transom hooks are a new territory in foam build.

    The transom is 28 density and has 7 layers of 17 oz each side of where the transom hooks would go...I was going to overbore the 1/2" bar to say 3/4" and fill with milled glass bog 50/50 cabosil.

    But the cleats are sooner in the build, so the rest is a bit of digress.
     
  8. fallguy
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    fallguy Senior Member

    The bow eyes I plan to overbore same like 3/4" for 1/2" rod and backing plate AND am butterflying a 12" smoothbore stainless "0.080 tubing that will cover the bow externally to help with any lateral forces. Again, I digress a bit. But the work is already ordered.
     
  9. Blueknarr
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    Blueknarr Senior Member

    My music festival sketch of a very high load thru bolt.

    15328378877472131957690.jpg
    There are many other possibilities. I have also used metal plate were the G10 is shown. It could be tapped so no bolts project into interior

    I removed and replaced core before laying second skin
     
  10. fallguy
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    fallguy Senior Member

    So, for wet bagging, would you modify the core and make it whole, if you will, and then secondary bond the modified core into the typical core layup (glass each side)?
     
  11. Blueknarr
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    Blueknarr Senior Member

    Something like that.
    There are probably hundreds of possible solutions. Most load dependent. You NA/designer might suggest a preference.

    Your drawing is simpler than mine and would work if foam cutaway allows sufficient room for backing plate.

    I am appalled by how often I see damage caused be poor craftsmanship in production boats. It takes me many hours to repair a localized crushed core around a fastener. It would have only added a few minutes to build time to install non-crushable core initially.

    While you have the core exposed is a great time to work out stratified for fastener reinforcement.

    But unfortunately there is no single established method.
     
  12. fallguy
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    fallguy Senior Member

    How large a backer plate for 8" cleat?
     

  13. Blueknarr
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    Blueknarr Senior Member

    How large a backer plate for 8" cleat?

    Something around 3x9. ought to work
     
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