How to seal plywood flooring?

Discussion in 'Wooden Boat Building and Restoration' started by tom12910, Mar 17, 2016.

  1. tom12910
    Joined: Mar 2016
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    Location: md

    tom12910 New Member

    Hey there guys. I'm completely new to this boat wood building thing so please bear with me.

    The boar in question is actually an inflatable boat that I want to create a wooden floor for. The floor will not really come in contact with with only from splashes and maybe our boots. The flooring will also be carpeted with marine grade carpet. I was wondering how do I water proof the flooring from the splashes and what not?

    I was considering using a fiberglass resin coat.
    (Bondo 1 qt. All-Purpose Fiberglass Resin)
    then just painting it with normal outdoor paint.

    If you guys recommend something else, do you mind adding name brands or something. I'm having a tough time with this, thanks!
  2. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    Polyester resin will not waterproof the wood better than a good quality alkyd enamel. Epoxy would be the best barrier. An inflatable boat will eventually take on enough water to soak those floors.
  3. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I would consider an inert material for your sole, instead of wood. Once you cover wood with carpet, it's just a mater of time before you have issues, regardless of the coated this wood might have.

    If you do insist on wood, epoxy is the only real choice and every surface, every cutout, notch, hole, etc., needs to have a minimum of 10 mils of epoxy on it, especially the end grain and screw or bolt holes. This means 3 coats of neat epoxy, fully encapsulating the wood.
  4. missinginaction
    Joined: Aug 2007
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    Location: New York

    missinginaction Senior Member

    Both the above posts are accurate advice. You might wince at the cost of coating with epoxy since the coating will possibly exceed the cost of the plywood itself but it is the only way to protect it.
    I took PAR's and Gonzos (and others) sealing advice almost a decade ago when I did an extensive restoration on a small cruiser. I have not had a single issue thus far with any wood substrate deterioration. You do need to pay attention to details. Every screw needs to be beaded in (I used marine sealant, and dipped each screw before I inserted it. Bolt holes need a little extra attention. I learned a technique here of locating the hole then over drilling it. For instance, say you're installing a 1/4 inch bolt. You might drill the hole 5/8 inch then place some packing tape on the back side of the opening. Fill the opening with epoxy resin and let cure. Once the resin is solid drill your 1/4 inch hole through the center of the epoxy. This method gives you an epoxy grommet or doughnut that completely protects the wood, water can never get to it.
    Yep, it's more work but if you want the boat to last it's worth the time and effort.
    Good Luck!

  5. Stumble
    Joined: Oct 2008
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    Location: New Orleans

    Stumble Senior Member

    Epoxy sealing is the only way wood will last in this application. But I would really recommend switching to something like G10 instead. It may be more expensive up front, but the ease of dealing with it and durability will pay dividends for years.
  6. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Consider using some PVC decking material and no carpet. It'll look nice, offer good traction under foot and can't rot.
  7. pauloman
    Joined: Jun 2010
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    Location: New Hampshire

    pauloman Epoxy Vendor

    if using epoxy, consider using an epoxy paint rather than a more brittle raw resin marine epoxy. You can still use fiberglass cloth with the epoxy paints.

    paul oman
    progressive epoxy polymers inc

  8. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Epoxy paint will not encapsulate the wood and if carpeted over, you'll have issues pretty quickly with just paint under it.

    Good to see your post Paul. I hope things are getting better in your world, in this new year.
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