Best way to seal wooden hull

Discussion in 'Wooden Boat Building and Restoration' started by bubblehead620, Jul 1, 2014.

  1. bubblehead620
    Joined: Jul 2014
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    Location: Brighton, TN

    bubblehead620 New Member

    Question for PAR

    Which type of epoxy do you recommend? If it isn't available at Lowe's or HD, where would we find it? What type of sheathing are you suggesting? Something like fiberglass mat or something else?

    Just for info. Our trailer has two walkways alongside the model - one on each side. We used 3/4-inch Marine plywood as decking We were going to use something like Rhino lining as a non-skid type decking paint. A manufacturer's rep told us that it would be slippery when wet. We tried non-skid pads with adhesive backing and they wouldn't stay in place. The truck-bed liner paint is usually a lumpy type finish due to its thick makeup and we'd prefer smoother finish. Is there a durable liner paint that is reasonably smooth? Bublehead620:?:
     
  2. dinoa
    Joined: Oct 2007
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    dinoa Senior Member

    Maybe fair then coat with coal tar epoxy followed by overcoat of flat black house paint
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    All of the marine grade epoxies (major suppliers) have similar physical properties, so it's just a matter of price. Marinepoxy from bateau.com or one of the products at epoxyproducts.com will likely be the cheapest.

    The sheathing would be cloth and any weight from 2 to 8 ounce will do, with the heavier fabrics, requiring more goo to wet out and fair. Neither of these products are available at the big box stores, so online shopping would be best. They'll ship it right to your door.

    There are several types and brands of truck bed liner. I've given an overview here:

    http://www.boatdesign.net/forums/al...-personal-link-thread-40721-4.html#post682997

    Some can be applied without much texture and most aren't slippery when wet, which is one of the selling points for this type of material. Also some can be sanded fair and smooth, then buffed to any luster you might want, though most will "caulk up" with UV exposure time. Many truck bed liners use particulates for the texture and these can be filtered out, which is messy, but produces a much smoother finish.
     
  4. 300wm
    Joined: Jul 2014
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    300wm Junior Member

    I used to build knives as a hobby. I tried a number of things to seal the wood so the knife could be left in dish water and not hurt the wooden handles. Epoxy is the only thing I have found that did it, and it usually takes more than one coat. The yak I'm doing, now, will have two coats of epoxy before paint. It will be 100% water proof.
     
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    It's all about film thickness with epoxy and usually 2 coats isn't enough. The usual recommendation is 3. The first a sealing coat, which is often put on hot, with two subsequent over coats (room temperature) to bulk up film thickness.
     
  6. sdowney717
    Joined: Nov 2010
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    sdowney717 Senior Member

    Not sure I want to get into this but,
    look at my black rubber hull coating.
    It is polyurethane rubber, PL roof flashing sealant adhesive and very flexible and sticks to metal and wood wonderfully and 100% water proof and is UV proof, hey it is made for roofs..., made by Loctite.

    You buy it at the Home Depot.

    I basically smeared on a layer using a 6 inch putty knife. Once cured it is sandable to smooth it. Or could be faired with another flexibletype filler .

    I also mixed some 1/32 milled FG fibers at about 30% to see what happens and it makes the rubber harder and a little easier to smooth if anyone cares to know!
    I think it does that by making the rubber thicker, more viscous, so a little easier to smooth. But you do not need that at all to get a fairly smooth coat.

    This also takes paint very easily.

    Anyway all who have seen it thinks it is pretty cool idea for a boat bottom.

    The Black PL has a shore hardness around 40 while 3m's 5200 is closer to 70.
    Which means the black PL stretches easier, my sense it that means it yields easier so more likely to not stress the wood- goo bond as much as 5200 might when the wood moves.
    Black PL is also a lot cheaper at $6 for 10 oz tubes.

    Sticks to wood incredibly well. And also to itself, more layers bond very very well onto itself.


    here is underwater hull area forward
    [​IMG]


    Coating with black PL over top of another poly coating. I had ground off the bow area to bare wood completely and this is where the 2 coatings merge.

    [​IMG]

    Transom covered with black PL, and the bronze swin platform brackets, and the struts and the rudders.
    This will seal the underwater metals from the ocean, so should be less corrosion potential and also zincs dont have to work so hard.
    [​IMG]

    Keel stripped to wood and coated both sides took 10 tubes.
    [​IMG]

    Oh, and I did a 5 years underwater ocean test on this hull with Black PL exposed to the sea, and it came out unchanged still fully intact, bonded like the day it went into the water.
    The other yellow coating, I was not as happy with, it wanted to peel between layers, and it completely came loose from the keel. Likely due to the keel wood being old white oak it has shore hardness of 70.
    I had to physically rip and tear off the yellow stuff, it was not falling off the wood. But I want what I put on to be a tight bond. With the yellow stuff, I think the old oak moved more than the yellow could easily stretch so it was constantly stressing the bond. Lets just say, I will not be buying any more of that yellow poly goo.

    The black PL is a vastly superior material to work with.
     
  7. pauloman
    Joined: Jun 2010
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    Location: New Hampshire

    pauloman Epoxy Vendor

    PAR is in the right direction - epoxy paint (more give and flex than epoxy resin) with or without fiberglass cloth. then paint over the epoxy.

    best to sell 100% of the model with epoxty paint - not just certain areas

    paul oman - progressive epoxy polymers inc
     
  8. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Good to see your post again my friend. I hope all is doing better on your home front.

    I'm not sure which product Sdowney is referring, can you provide a brand name and product type? I've done a lot of testing on polyurethanes and polyureas in recent years.
     
  9. sdowney717
    Joined: Nov 2010
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    sdowney717 Senior Member

    Sure, it is the black PL poly roof flashing PL S30
    This is the technical data sheet
    http://www.loctiteproducts.com/tds/PL_SEAL_RF_tds.pdf

    Their own test was done underwater for 10 weeks at 122* with movement cycling and it passed.

    My own use underwater for 5 years on some small areas of the hull passed with no change, no peel off or letting go.
    I specifically used it to repair - seal the shaft log along with the more liquid sikaflex grey concrete crack seal. And on some underwater seams.
    Pl S30 shore hardness is 30 and for 3M 5200 of 70 means this is easier to stretch, so my thoughts it stays on the wood with less chance of pulling free when the wood moves.

    Link to HDepot
    http://www.google.com/shopping/prod...jgbRLdXQ-aOp85QtLbizAOzmoR0_ZQF1zYRoCv4Dw_wcB
     
  10. garren
    Joined: Mar 2009
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    Location: Billings, Montana

    garren Junior Member

    Mr. 717,

    What do you spread it with and does it come in colors other than black? Might be a good coating for a drift boat bottom.

    Gary
     
  11. sdowney717
    Joined: Nov 2010
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    sdowney717 Senior Member

    http://www.loctiteproducts.com/tds/PL_SEAL_DWS_tds.pdf

    If you read the PDF, the product seems the same except for color.

    Says available in white, bronze, gray, redwood tan, and black.

    I was spreading it with a 6 inch flat putty knife blade. Basically like putting frosting on a cake. It stays soft for several hours and slowly gets stiffer, so gives a long working time. After a day, it is set but not fully cured.It will feel sticky for days but it is cured. Eventually it is no longer sticky feeling.

    It can be sanded with coarse paper till smooth. Or could be faired with some kind of flexible stuff, or just fair with more black PL.

    It can be painted, paints stick very well. I plan on of course, painting bottom paint on this. Yes the surface is quite tough, resistant to being scratched. It is very much like tire rubber.

    Imagine a tire surface type feel on whatever you put this on, that is what you will get. It is also before any sanding has a glossy appearance and when wet feels slippery under my hand.

    Buy a tube to experiment with. I mixed some 1/32 milled FG fibers into this at a 30% ratio to experiment. It made the rubber have a harder surface, thicker when spreading. I suppose you can make a tube go further when adding milled fibers. It could have FG cloth embedded in this. It would still flex but loose the stretch. I think I will use this in some cloth on a large flat surface on the boat top where normally you would use FG cloth and resin. I do that because It is cheaper and more convenient than epoxy, and still can flex with no cracking. And I can sand it smooth for paint.
     
  12. sdowney717
    Joined: Nov 2010
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    sdowney717 Senior Member

    When I was spreading a lot of this, it has a smell just like chocolate. It really does, it does not make you feel ill. It is outside in the open air.

    I filled a crack between timbers on the keel using black PL mixed in with cotton seam caulk. Did very well. I could have just used black PL alone, but wanted to try it combined with what wood boats traditionally use, cotton caulking between seams tapped in.
    Using cotton mixed in, I was able to force in a fair amount up into the crack.

    I was having some trouble sealing this, now rain water cant drain out of the keel, so the sea wont be able to enter.

    This is where 2 very large oak timber joins come together.

    [​IMG]

    You can see the large timbers faintly outlined and coated with black PL which is also showing the gloss look. No worm shoe on here yet

    [​IMG]

    Other side, the whole keel took 10 tubes of black PL. This is a large keel on a 37 foot boat.

    Where keel meets garboards, I thickened the black PL with the 1/32 milled FG fibers and formed a fillet. Let it slightly cure, then smoothed using my finger, look very nice.

    [​IMG]

    Cleanup for my hands is Great Value blue dish soap from walmart, like Dawn,a ss scrunge, and water. That works so much better than using a hydrocarbon solvent. So it is easy on your skin.
     
  13. garren
    Joined: Mar 2009
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    garren Junior Member

    Thanks. I think I'll grab some and do a little experimenting.
     
  14. oldsailor7
    Joined: May 2008
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    oldsailor7 Senior Member

    Buy, Borrow or Steal a copy of "Wooden Boat Building and Repair with Bote Cote Epoxy".
    But be aware 'Bote Cote' is only available in Australia. (Boatcraft, Brisbane,) with outlets in all major centres.

    Elsewhere, ---- post "Boat building Epoxies" in Google.
    Just make sure it is a quality epoxy with 100% solids, and only thin with non evaporative thinners.
    Two coats on the insides, three coats outside----no glass cloth needed.
    Glass tape on the seams only. There are wooden boats still sailing today which were built with Bote Cote forty years ago. :eek:
     

  15. sdowney717
    Joined: Nov 2010
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    sdowney717 Senior Member

    Updating my experience, everything is still great on using the black Loctite PL S30 on top the wood.

    Paint on hull side is still smooth and looks just like it did in 2014.

    I am sealing in the forward window glass. I had tried many other things, but they would eventually leak. Same thing was happening with a 1/2 inch thick Lexan clear glass laying in a hatch rabbit. Finally using the black PL, no leaks so far for 6 months.

    And that black PL is holding ok so far on the glass to epoxied wood frame rabbit.
    My technique, is run a bead on the wood rabbit and smooth with my finger.
    Lay the glass in place.
    Run more around the glass edge filling up the space, smooth with finger, move glass around to help removing trapped air bubbles, they show up when you drag you finger around the seam as tiny hills in the black PL.

    Then after 2 days of cure, clean up glass with a razor blade.

    Another repair, I used a heat gun and stripped off all the paint coatings on the surrounding wood window frames. I had found some rot in one of the lower mahogany window frames where it meets the cabin top. I dug out all the rot, then treated the wood with oxalic acid. then without washing that away after it dried, I fashioned a piece of treated pine and glued it into place using Loctite PL premium polyurethane construction adhesive mixed with sawdust and submerged the wood in the glue mix. After it cured that day, scraped it smooth.

    Then I overcoated with a skin coat 1/16 to 1/8 in thick of black PL using a 6 inch putty knife, like frosting a cake.

    2 days later, used a random orbit sander 120 grit and dry sanded the black pl smoother. It really does sand down. The goal is to knock off the tops, not necessarily smooth to the valleys. It will look really smooth when your done.

    Then rinse with a hose, let it dry.
    Then over coat using the trowel with DAP Dynaflex white 230 to fill in the valleys. Let dry a couple days and re-sand a little. The surface is now really smooth and ready for paint.

    My goal has been to waterproof seal the wood under a black rubber coating so that no water can pass to damage the wood. And it has been working. Since it is a rubber, it sticks well and moves if the wood moves, son no possibility of cracking.

    And this black PL rubber is really abrasion resistant. We had a wind storm, I forgot to put out my bumper, the hull side rubbed against a neighbor's boat deck, all it did was abrade off some paint, the black PL was not gouged or penetrated.

    I will post some pics early next week of the window frame sealing.
     
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