Some basic inside hull epoxy painting questions

Discussion in 'Wooden Boat Building and Restoration' started by flyingvranch, Jan 24, 2017.

  1. flyingvranch
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    flyingvranch Junior Member

    I am thinking ahead on my boat build and have a few questions.

    It's a fairly large jon boat style plywood boat that I want to use for fishing. It will live on a trailer under a carport when not in use. I want to encapsulate the hull in epoxy/glass on the outside and plain epoxy on all the interior surfaces. I plan on painting the inside of the hull probably gray.

    My questions are should I encapsulate with West Systems epoxy and then sand and paint or is there a way that I can tint the epoxy and do all of this in one step? Is there another product that is a two part epoxy paint perhaps that will do the job of encapsulating the wood so that it is smooth and washable? If I have to epoxy first and then paint, what type of paint should I use that is hard and smooth and glossy.

    My goal is a smooth sealed interior surface that I can scrub clean without water getting to the wood itself. I have built several boats nearly 30 years ago and now there are so many new options and I am unfamiliar with the new methods. I see pictures of boats that look like the interior cockpits are fiberglass gelcoat and I am going for that look myself hopefully.
    Thanks!
     
  2. upchurchmr
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    upchurchmr Senior Member

    Tinting epoxy usually ends up not looking like paint or your old gelcoat.
    The color is "thin". Not completely colored.

    You would be better off fiberglassing the inside with epoxy as well as the outside.
    Epoxy by itself is not very strong or abrasion resistant. I tried this before and was always fixing the epoxy only coating.

    Are you going to use fairly thick plywood for the hull? If it is thin, then there is a real use for the glass on the inside for strength. when you hit something on the outside, its the inside surface that breaks. The glass will add lots of strength.

    But if you have a thick hull, a thin layer of glass does not add a lots of strength.

    Personally, I suggest glass epoxy, then a fairing compound to fill in the weave (epoxy and microballons, etc.), sand smooth, then paint. This is the easiest way to make an epoxy coating to keep the plywood protected.
    You probably know that epoxy is damaged quickly if you don't have spar varnish (UV or sun ray protected) or paint, and paint protects a lot more.

    I built a wood/ glass/ epoxy row boat that people would not believe was wood - so it can be done.

    I helped a friend build a pirogue in the same manner and he is very happy with it. But it was not a gloss finish - he just wanted it done.

    A 2 part epoxy paint will not have the water protection as the epoxy glass does - but it will be pretty good. If you go for the 2 part paint, just make sure any end grain, footballs or damage in the surface of the ply is sealed with epoxy - even if it is just locally. Damage or endgrain is where the ply will rot quickly.

    Sorry if that was too simple. Just trying to get your questions all at once. :D
     
  3. flyingvranch
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    flyingvranch Junior Member

    Thanks for the reply! I was not planning on using glass on the inside as it has a lot of frame members, and nooks and cranny's that would be a real chore to try and cover with cloth. I was planning on just brushing on epoxy and then painting for UV resistance.

    My plywood is 1/2" so I think it will be pretty sturdy for what I plan on using it for. I am using 6 oz. cloth and epoxy on the outside with extra tape around the hard chines and edges.

    I plan on sanding all the surfaces smooth and easing all of the sharp edges of the frames etc., so that the epoxy will hopefully hold up well without too many chips.
     
  4. upchurchmr
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    upchurchmr Senior Member

    So it sounds like you already had your plan.
    But if you thought about glass on the inside, just glass the ply on the inside before you assemble it to the boat. Then you don't have to worry about the frame members - you just assemble the boat in the normal manner. Then glass the outside when the hull is complete.

    Good luck
     
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Using a brush to apply epoxy is the most wasteful method there is. Using West System epoxy is the most costly brand there is. Use 'glass fabrics where you expect some foot traffic, to protect these areas.

    Download the free user's guides and epoxy book from westsystem.com and systemthree.com, which will help you through the various techniques. Also have a look at my tip's and tricks page on my site.
     
  6. Scot McPherson
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    Scot McPherson Senior Member

    I can't see a need to glass the inside of a jon boat except to protect from foot traffic like Paul said. Lots of boat paint is just epoxy based paint. Selecting the right paint is probably what you are looking to do. Select a good grey colored epoxy hull primer is probably as far as you need to go, and maybe recoat it with a nice top sides paint if you want a nice finish.
     
  7. upchurchmr
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    upchurchmr Senior Member

    Gee.

    Good abrasion is the same thing as foot traffic?
     
  8. Scot McPherson
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    Scot McPherson Senior Member

    foot traffic is regular, occasional abrasion is not. The bottom underfoot is going to be worn much faster than the interior sides will be. If you suspect some spots will get abraded more then lay up some glass there.

    When my father mentioned his Mako getting scratched up from pulling crab traps (6 as a recreational crabber), I told him to glue some M3 to the hull where the traps hit. problem solved...Don't need to coat the whole boat for a few spots that get hit more often than others.
     
  9. sailhand
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    sailhand Junior Member

    Flyingvranch I have used an epoxy flowcoat from the west system suppliers in australia. This is extremely hard and I have attempted to sand a couple of areas with cubic zirconia sandpaper and found it to be ridiculously hard and almost impossible to sand. It does yellow in the sun apparently but i haven't found it to be problematic. You can clearly see the colour change but it doesn't seem to affect the strength of the paint. It is very very tough and durable it has been on my 44ft cat for 15 years and I tried to sand it 12 months ago and gave up after a couple of hours I think when the time comes I'll have to grind it off.
     
  10. flyingvranch
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    flyingvranch Junior Member

    Thanks everyone for the great information! I have a plan in place for the outside of the hull using glass cloth etc., and the outside will be protected by adding sacrificial raw wood rub strakes bedded to the hull. It's the inside that I am perplexed about.

    I have already planned to build some removable floorboards constructed of red cedar much in the same fashion as what is seen in the cockpits of small sailboats.

    Fishing for large catfish is bloody and muddy business so I want to be able to lift out and remove the floorboards and hose out the inside when at home.

    For a better explanation of the type of boat that I am building here is exhibit "A".

    My boat will be configured different on the inside but the hull is exactly the same.

    Thanks!
    Bud
     

    Attached Files:


  11. pauloman
    Joined: Jun 2010
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    pauloman Epoxy Vendor

    if you are "painting on epoxy" without fiberglass you need to use a more flexible epoxy paint rather than the more brittle boat building resins. You can also use these epoxy paints with fiberglass cloth

    paul
    progressive epoxy polymers inc
    epoxyproducts.com
     
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