Encapsulating bilge of my new build

Discussion in 'Boatbuilding' started by gwoloshyn, Dec 5, 2012.

  1. gwoloshyn
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    gwoloshyn Junior Member

    Hi everyone, I'm new here an an amateur boat builder. I'm working on a 16' Glen-L Outrage and in the encapsulating process with a few questions.

    I've coated the bilge bottom where all the water will actually sit, but is it necessary to coat all the areas on the sides of the boat too? And, more specifically, is it necessary for me to apply epoxy to the UNDERSIDE of plywood floor boards?
     
  2. PAR
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    PAR Yacht Designer/Builder

    Encapsulation is just as the word suggests, you entomb the pieces, in plastic, so moisture content remains stable. If the boat is assembled, this is very difficult to to effectively, as many places aren't accessible for epoxy.

    The short of it is, encapsulation isn't a surface treatment. If you try this, you're actually better off with just paint or varnish, as these will permit the wood to breath. The only time I recommend epoxy surface treatments on plywood is to seal the end grain and fastener holes, where are very prone to moisture ingress and problems as a result.
     
  3. gwoloshyn
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    gwoloshyn Junior Member

    Thanks. I had planned on applying epoxy to the top of the floor before I layed down carpet, I'm under the impression that water wil be trapped between the two therefore epoxy would prevent the wood from rotting. Would you say paint instead of epoxy will provide the same protection?
     
  4. PAR
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    PAR Yacht Designer/Builder

    Applying carpet over wood, encapsulated or not, has kept me in lots of work over the years. If you want to kill wood fast, apply carpet over it.

    Epoxy only protects wood if it can stabilize it's moisture content. The only way to stabilize it's moisture content, is to encase the wood in epoxy, especially the end grain, fastener holes, cuts outs, notches, etc. A 10 mil coating is the minimum, which usually takes three coats.

    If you just top coat the piece you're putting carpet over, the moisture will work around the edges, into screw holes, end grain, etc. and it'll rot, guaranteed. I must do a hand full of carpet covered bass boats each year, just because of this.

    My point is epoxy is a commitment, of which most don't realize. Unless it's used as a glue (at which it's really good), encapsulation is a total process of embalming wood. Every square inch, inside holes, everywhere or you're just making a bigger problem. Once wood is partly covered with a hard plastic (epoxy), moisture can get in, but has limited ways to get out, so rot sets in. It's an all or nothing deal.

    Simply put, if you can't embalm the wood with epoxy of sufficient film thickness, then the best thing is no epoxy. Of course, carpet over painted wood just causes the wood to rot too. The only time carpet can be used in a boat is when you can remove it during storage or you store your boat in a climate controlled environment. Carpet is fine for your bedroom, but really isn't the best material under foot on a boat. Even the indoor/outdoor stuff causes mold, mildew and other issues under it, unless it's permitted to air out and dry (the removal thing).

    Painted, natural or oiled finishes hold up best, under foot on a boat. Truck bed liner is a great product under foot, as it seals and offers great wet foot traction too. Nope, not as comfy as carpet, but way more durable. If you drop a slimy fish onto a carpet, you'll never get the smell out, but you can just wipe up a painted surface and call it a day.
     
  5. pauloman
    Joined: Jun 2010
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    pauloman Epoxy Vendor

    on a slightly less 'intense' spin compared to PAR's very sound comments, a thin coat of epoxy generally makes a good primer (plus at least some sealing) that will help your varnish or paint last longer - maybe reduce plywood checking etc.

    keep in mind that epoxy and paint expand and contract with temperature while wood expands and contracts with moisture. That said, plywood doesn't expand/contract much.

    I've built several plywood kayaks etc over the last 10 years or so. My thoughts change with each construction, but currently I would 'prime' all surfaces I could reach with either solvent thinned epoxy or an mcu (moisture cure urethane - aluthane).

    This isn't the 'last forever fix' everyone is suggesting, but rather a longer extension between restorations/repairs.

    under seats and decks I might leave the plywood uncoated.

    paul
    progressive epoxy polymers
     
  6. sean-nós
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    sean-nós Senior Member

    I am building the Glen-l crackerbox and have encapsulated all of the timber with 3 coats of epoxy the ply wood floor and seats will also be done top and bottom making sure the sides of the ply get a good coating, I also gave every thing a few coats of varnish for uv protection and to be sure to be sure:D

    [​IMG]
     
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  7. gwoloshyn
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    gwoloshyn Junior Member

    Your boat looks great. I see you have a real nice level epoxy coating, which I can't achieve. I'm applying my epoxy with a west foam roller and going slow, but still getting craters and dips all over.

    I guess I still need more experience..
     
  8. sean-nós
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    sean-nós Senior Member

    I find very thin coats are better than thicker ones and using one brush to paint it on and another dry fine bristle to tip out any lines or bubbles you can get quit a good finish where as if you use a roller on the inside of the hull you will fine a bit more epoxy been squeezed out of the roller on the frames and battens causing runs.
     
  9. michael pierzga
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    michael pierzga Senior Member

    Some epoxies brush better than others. Epiglass by International is very thin and brushes like paint. West is honey like.

    Also remember the hot air gun trick to make resin thin and flow on the surface after you have rolled or brushed it on.
     
  10. PAR
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    PAR Yacht Designer/Builder

    A brush is not the best way to apply epoxy (one of the lest efficient in fact). Brushes tend to cause epoxy to pool at the very start of the first stroke and then it is just smeared around, leaving a not very uniform coating. A uniform coating is the real goal and this is best done with rollers, squeegees, plastic applicators and putty knives. After application, you can tip off if you want, which is best done with a fairly dry foam brush, held nearly vertical to the work. Of course, some times a brush is the only thing, that will let you get into corners or tight locations, so some brush use can't be avoided, though you should try. Most epoxies have sufficient viscosity to wetout fabric, which means it'll wetout wood just fine too. Raka and Epiglass are known for being thin, but this can be troublesome with other areas of the build.
     
  11. gwoloshyn
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    gwoloshyn Junior Member

    Thanks for the info. If I could ask another question related to this.. I'm building some floor supporting frame work in the bilge area out of 3/4" exterior grade plywood. This framework will not be in direct contact with any pooling water in the bilge, do I need to seal these pieces with epoxy? Should every wooden part in a boat be protected no matter where it is?

    I guess this also goes with coating solid wood. I heard that because of wood movement it could still crack an epoxy coat and let water in. What would be an alternative to epoxy if I were to build boat seats out of solid wood?
     
  12. sean-nós
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    sean-nós Senior Member

    Exterior grade plywood is nowhere near as good as marine ply but if you must use it I would give it a good few coats of epoxy, even if it's not in direct path of water it can still get splashed and when you have a cover over the boat there can also be a lot of moisture buildup."better safe than sorry";)
     
  13. PAR
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    PAR Yacht Designer/Builder

    If wood is properly encapsulated, movement will not crack an epoxy coating, of sufficient film thickness. It's elongation properties are very good in this regard. If the wood isn't fully encapsulated, you can pretty much bet the coating will move enough, to crack the epoxy.

    Enclosed boat spaces, can change quite dramatically in moisture content, just in use. A natural 15% in air environment can jump to 30-40%+ a few minutes after launch. This will test any coating, unless you've used encapsulation techniques.

    As I mentioned, if you take the epoxy route, you must go the whole nine yards. Other wise, you're just using really expensive plastic as paint. In the bilge is a classic high moisture environment, with limited ventilation and likely trapped boarding water, plus condensation. Plan accordingly.
     
  14. gwoloshyn
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    gwoloshyn Junior Member

    Thanks Par, I'll be encapsulating the remainder of the bilge which hasn't been coated yet. Just wanted to see if I could cut down on epoxy cost if it isn't necessary, but I won't be cutting corners and risking hard to fix problems down the road..
     

  15. LP
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    LP Flying Boatman

    You can also ask yourself if the component is a permanent part of the structure or if it is an accessory type component that can easily be removed. I have some interior "furniture" in my recent build that I can remove should I deside to change things up a bit. These pieces are only screwed into the primary structure. Should a person decide not to encapsulate everything, this would be a good place to make a transition. Make sure that the point attachment to the primary structure has the full encapsulation, but the furniture could be constructed by other means that are less intense than full encapsulation and also expect the performance of the surface coatings that you end up using on these other surfaces.
     
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