Divinycell decking

Discussion in 'Materials' started by E.W., Apr 13, 2020.

  1. E.W.
    Joined: Apr 2020
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    Location: Kansas

    E.W. New Member

    Hey guys, I am the owner of a new jon boat. I am planning on putting in a floor over the ribs. The ribs are 2” wide and they are on 14” centers. This is a non structural part of the hull, it just needs to support the weight of people/coolers etc... Can you guys give me a starting point on what thickness and density I should start with if I was using divinycell foam core? FYI, I am using epoxy and fiberglass. I am wanting to keep the flooring lightweight.

    thanks

    Eric
     

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  2. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    Welcome to the forum Eric.

    Is the main purpose of this floor simply to have a uniformly level surface to stand on / rest your coolers on?
    If so, then I think I would be inclined to put down a timber lattice framework, with longitudinal boards and transverse timber connectors on the underside, in between the transverse aluminium top hat ribs shown. While keeping the panels small enough such that they can easily be removed for cleaning underneath.

    Re a divinycell / epoxy glass floor, this seems to me to be a bit of an overkill.
    This following suggestion might be a bit unorthodox, but I have seen a lot of small boats here fitted with floors (or soles to give them the more correct name - floors are technically transverse frames that support the soles) that are made from ordinary 3/4" thick 'plastic board' (as we call it here) - this is standard foam boards with a plastic laminate on each side, as used for building kitchen cabinets. If you 'scuff it up' a bit you can laminate on it - I built a wheelchair ramp 10 years ago for a friend using this plastic board (also 3/4" thick) and it has held up well. Although I did use epoxy and a layer of stitched glass mat (rather than polyester) on the top side (only). And then paint it with non-skid paint.
    What ever method you choose, I think you need to design it so that the panels are in a logical sequence, perhaps labelled / numbered, and they can be easily removed and re-fitted in order to clean underneath.
     
  3. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    Wood plank floor done in 8 hours. Foam core would take about two weeks. Laminate side A, Laminate Side B, decore edges, infill edges, paint bottom and sides, screw down and pull up and decore holes and refill. Screw back down or paint and then screw down.

    Timber with some screws easily a one day job. Two if you add a finish other than oil.

    wood has a natural wear layer, paint doesn't, so timber is also lower maintenance if you use the right woods
     
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  4. E.W.
    Joined: Apr 2020
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    Location: Kansas

    E.W. New Member

    I agree that are way easier/cheaper ways to do this. I should specify more, this is for a boat that will be frequently beached/stuck. Every pound in the boat is a pound I have to drag off the sand bar, so I want to make it as light as reasonably possible. I don’t mind the time it takes to do composite work well, I have some future boat building plans and I would like to experiment with the scraps of this project. I Have done work with ply core, but never foam. I was thinking about either 1/4” or 3/8” in 5lb density, but that’s just from trying to read tech specs and looking around the net.

    Thanks for the help guys

    Eric
     
  5. fallguy
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    fallguy Senior Member

    You need about 12mm core with about db1700 each side. Some people like 1708 for a wear layer, but for me, no thanks.

    Trim it to fit and glass each side on a perfectly flat table or over a plastic sheet in the boat if camber.

    Then flip and glass reverse.

    Then you need to decore the edges and decore the screw locations. Edges like 3/8", screw locations 2x screw thickness. Some people might decore screw locations before glass, but I would after so you don't delam when you screw it down.

    Then you fill the voids with very thickened epoxy. Thin epoxy will sag out of the void. Let it cure. Sand it out; fill again if needed.

    Paint the bottom of the core with an enamel.

    paint the top with skidproof paint

    there are variations, like using peelply and you'll need to sand and epoxy primer is generally used; this is the basic idea
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    What is the length of the piece to be installed ? If 8 feet or less, waterproof ply seems the obvious solution.
     
  7. E.W.
    Joined: Apr 2020
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    Location: Kansas

    E.W. New Member

    Thanks for the input guys
     
  8. ondarvr
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    ondarvr Senior Member

    Lightest and easiest, honeycomb, buy it, cut it to fit, secure in place.
     
  9. fallguy
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    fallguy Senior Member

    Do you mean preglassed comb?
     
  10. ondarvr
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    ondarvr Senior Member

    You can get it with a finished surface on each side, cut it to shape and Install it.
     
    Last edited: Apr 15, 2020
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  11. ondarvr
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    ondarvr Senior Member

    Most of the time I just tell people to use exterior grade plywood and paint it with non skid paint, or better yet leave it uncoated.

    This makes it a cheap project that can be finished in an afternoon.

    7-10 years later if it needs replacing it will take less time because you have the current plywood as a template.

    In boats like these I don't even fasten the plywood in place. Just mount it so it doesn't blow out on the road.

    This isn't the sexiest way to do it, but we're talking a small aluminum jon boat here, no amount of money, carbon or epoxy is going to change that.
     

  12. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    just put notches in the ply where the ribs are. One needs to be careful that sinkers or swivels don't end up lodged against the hull, where you can't see, otherwise electrolysis can see a hole developing.
     
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