Breast hook/ west six 10 epoxy

Discussion in 'Boat Design' started by Fadetoblack188, Apr 24, 2021.

  1. Fadetoblack188
    Joined: Apr 2021
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    Fadetoblack188 Junior Member

    How strong is west systems six10 epoxy? I cut and installed the breast hook on my 16ft dory’s new rub rails last night.

    there will be a bow light and a 4-5 inch cleat getting fastened to it.

    my question is, is the epoxy strong enough alone to keep that breast hook secure? It’s a 16 ft fiberglass dory and the tensile strength of the epoxy says 6,438lbs. I can’t see with the anchor line out even in some heavy current it ever seeing 6k lbs.

    The angle is super tuff if I had to pre drill and put some 3 inch screws in from the outside rub rails through into the breast hook.

    I was thinking of running a piece of 3/4x3/4 white oak to match underneath the breast hook expanding to under both rails on both sides this would also help with the force being applied to the cleat. Or some other way to reinforce it from underneath. Can I just epoxy fillet or fiberglass underneath

    What are your thoughts?
     
  2. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    Welcome to the Forum Fade.

    One can generally say that epoxy is very strong stuff indeed - often stronger than the timber it is bonding, in that the timber will fail before the epoxy will.

    Can you post a photo or two please of the bow of your boat showing the installed breasthook?
    As the saying goes, 'a photo is worth a thousand words' for explaining things.
     
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  3. Fadetoblack188
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    Fadetoblack188 Junior Member

  4. Fadetoblack188
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    Fadetoblack188 Junior Member

    Posted.. thanks
     
  5. fallguy
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    fallguy Senior Member

    I'd put a piece of 1708 up under there and to the gunwhale and hull, if practical on the hull

    Wet it out on plastic and tinfoil on a table like Rutan did the airplane work, use peelply to keep it from running all over or stand by with an acetone rag for an hour

    prewet the wood

    The glass will keep the wood from cracking. I'd also laminate the top with 4-6 oz to prevent cracks and backer the cleat with plywood or quarter inch frp...you can blend the glass in an it'll be invisible, but function, stain first if planned; that part will be tricky if you are staining..

    If the screws are running across the grain, it'd help, but if they are parallel to the grain, they might cause an early fracture

    sure looks nice
     
  6. fallguy
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    fallguy Senior Member

    As long as you are doing some more work, I'd also overbore the cleat bolts and add thickened epoxy so any leak won't rot it..typically 1/4" goes to 1/2", but make sure the cleat covers the overbore..
     
  7. Fadetoblack188
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    Fadetoblack188 Junior Member

    So you feel if I just glass in some 1708 strands on the bottom extending across it will make it strong enough?
     
  8. fallguy
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    fallguy Senior Member

    I go all the way across it on the bottom and protect the part from the sun above with glass..it will like to expand at different rates and likely crack on top.

    otherwise do nothing and varnish both sides; worst case you lose the boat while towing or an anchor if the cleat breaks

    It looks pretty strong to me, but if you want a third option, a couple two inch strips of 1708 would ensure the bond and you can still stain and varnish easier

    ..decisions..
     
  9. Fadetoblack188
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    Fadetoblack188 Junior Member

    I will be painting the top with marine primer and paint to match boat.

    I will strip the bottom with 1708 strands and hope for the best
     
  10. bajansailor
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    bajansailor Marine Surveyor

    As you are painting it, you could add a layer or two of glass over the top (and then fill and fair it), as well as all the way across on the underside, and that should make it pretty strong?

    Alternatively, would it be feasible to add a transverse timber frame / stiffener (perhaps a 2" x 1") on the underside of the breast hook at the aft end, long enough so that it can be tied in to the hull sides?
     
  11. fallguy
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    fallguy Senior Member

    If you are painting; then definitely hit the board with 4-6 oz glass. It'll open otherwise.
     
  12. messabout
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    messabout Senior Member

    The picture suggests that the grain of the breast hook is running athwart ships. It would have been more advisable to run the grain fore and aft. Since the job is already done, do as the others have suggested. A layer of epoxy and glass will make that part plenty strong enough to hold the bow cleat securely.

    If you are not sufficiently confident there is another option. Make up a giant washer to install underneath the breast hook. A 3/16 0r 1/4 inch aluminum or stainless plate will make the wooden part pretty tough. The idea is to spread the load across a larger area. ........
     
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  13. Fadetoblack188
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    Fadetoblack188 Junior Member

    as per the way the grain is running , this how it comes from the factory on these boats. I just copied factory.

    The boat only weighs 600lbs with motor.

    I don’t think the issue is the cleat itself ripping out. I think it’s the. Breast hook ripping out
     
  14. Fadetoblack188
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    Fadetoblack188 Junior Member

    I just
    I just did my best to mimic how these boats come from the factory. That’s how they run the grain on the breast hook
     

  15. Fadetoblack188
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    Fadetoblack188 Junior Member

    F43368D2-ED51-44B6-A964-089736E2BE47.png 1B587E2D-4630-45A8-AA98-22DBB36ED55A.png Here’s a couple screen shots taken right off their build page. Beats me


    Don’t laugh at my work after looking at these. They do it for a living! Mine was my first time even using a bevel gauge hahaha
     
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