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Thread: Glassing bottom of wood boat?

  1. #1
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    Question Glassing bottom of wood boat?

    I'm currently building a 13'00" Peapod out of Atlantic White Cedar, bead and cove construction. I plan on covering the entire exterior of the hull with 6oz. fiberglass cloth and TotalBoat 2:1 epoxy. My questions are? (A) apply a sealer coat of epoxy(and let dry or cure) prior to applying the fiberglass cloth or(B) apply the epoxy and fiberglass cloth directly to the bare, unsealed cedar?
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  2. #2
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    Default Re: Glassing bottom of wood boat?

    Either way.
    If you pre seal the wood, be up to speed on amine blush.
    Be familiar with kick off speeds of which hardener /volume mixed/ air temperature. The slowest you can use is generally better in terms of working time and how long the resin has to penetrate into the wood.
    I hope you are planning to glass the inside as well.
    bruce

  3. #3
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    Default Re: Glassing bottom of wood boat?

    Second the inside. I assume you're epoxying the actual ==((== seams as you go, so once cured you can remove any fastenings attaching the strips to molds. Glass the outside while still on the molds and strongback. Once cured, lift off and you have a nice clean interior to glass.

    There are lots of ways to glass. I like letting a surface coat tack a little and put glass down on that but many like to position the glass dry and apply epoxy over. Either way you need to work the epoxy in getting the glass soaked, transparent. I have better luck using a hard rubber roller to squeeze out the epoxy and really work it in evenly. I try to leave a bit of warp/woof texture that will be filled by a final coat of epoxy later.

    G'luck

  4. #4
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    Default Re: Glassing bottom of wood boat?

    Tank you, Wizbang and Ian! Just as I thought, either way is okay. Yes, I also plan on glassing the interior of the hull.
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  5. #5
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    Default

    When you set fiberglass cloth to Wood use a squeegee,

    the mistake we all make the first time we use epoxy and fiberglass is to use way too much epoxy.

    Mix small batches make puddles and draw away from the puddle until you saturate a large area, the cloth slowly absorbs the epoxy it doesn't happen instantly,

    it takes a little practice with a squeegee if you press too hard to cloth will move if you go to light you leave too much epoxy.

    You can work the epoxy until it sets up. if you see wrinkles you have too much epoxy under the cloth.

    It usually takes the four coats of epoxy to get a smooth surface without the weave showing,. It cannot be done all in one session without letting it set up between coats
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...0-Ducker-Resto

  6. #6
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    Default Re: Glassing bottom of wood boat?

    Itís easier to get the cloth straight if itís applied dry.
    For heavier glass, pre-wetting the surface helps a little in wetting the glass. Letting a pre-coat cure adds weight and the work of cleaning and smoothing it before applying the glass.
    Light cloth like that wets easily.
    If the boat will see many shingle beaches and you can tolerate a few more pounds, you might double up the glass on the outside of the bottom.

  7. #7
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    Default Re: Glassing bottom of wood boat?

    Since you don't list a location we can only guess at what waters and which types of boats you'll use it in, but I'd glass the bottom and the garboard strake to protect them from rocky beaches.

    Nobody has asked, but why are you fiberglassing a solid wood hull? Most builders will glass plywood hulls, but solid wood will have more movement, i.e. expansion & contraction from wet and dry cycles. This movement can crack rigid fiberglass coatings, so you might want to consider one of the more flexible epoxy coatings like G-Flex. Just sayin'...
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

  8. #8
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    Default Re: Glassing bottom of wood boat?

    I took bead and cove to mean that he's making a stripper, generally monocoque. Glass within and without is normal in that construction.

    The exact design is not mentioned but I'd bet the traditional peapod, a real crank to row unless loaded, has been pleasurized to make a good rowing boat. Rather than the traditional pod's heavy construction he's building light. It's a good advance.

  9. #9
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    Default Re: Glassing bottom of wood boat?

    I've never glassed over white cedar. Red cedar is very porous and the pores are full of air. Also, you may have the odd slightly open seam which will be full of air. As the resin soaks in it displaces the air which comes to the surface and makes bubbles. The only way I've been able to beat that has been to apply at least one primer/sealer coat, let it cure for a day or two then lightly sand it smooth. It helps to squeegee those coats often as it cures thereby breaking the bubbles that have formed.

    I prefer to use WEST Systems foam rollers when applying resin and I never apply the glass over wet resin because it's too difficult to move the cloth once it's down in the wrong place.

    And yes, don't apply more resin than it takes to wet all the way through, 6 oz. won't need much. Give it a few minutes to soak through and just add a little more where necessary.

  10. #10
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    Default Re: Glassing bottom of wood boat?

    oh.. and don't do epoxy on rising temps..may get "outgassing" ok if the temp is dropping..
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...0-Ducker-Resto

  11. #11
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    Default Re: Glassing bottom of wood boat?

    Also be aware that a pre-coat which is allowed to harden up (which it should be - then de-blushed if needed) will often raise the grain a bit. If you then try to apply the glass for the next layer without sanding down all those little stickers they make it much more difficult to drape the cloth and slide it around as needed to get it smooth, wrinkle and lump free.

    I always apply outside cloth with a Gougeon yellow foam roller, rolled and then immediately very lightly tipped using a hunk of roller hot-glued into a slotted stick (scrap strip) as a tipping brush. I often have the roller in one hand and the tipper in the other while my lovely assistant mixes me a steady stream of small, properly measured and mixed batches of epoxy. Her job is just as important as mine and keeps me from screwing up the mix due to rushing to do too many things at once. I use fast hardener for all glassing, but that may be too intense for some folks, as you don't have much work time. Fiberglass cloth will conform to the shape and lie down more smoothly with less hassle if you drape it dry, slightly oversized, and then go along with scissors and trim off the factory woven selvedge edges before you start saturating the cloth. It frees up the weave, allowing it to move on itself easier and adapt to curved shapes.

    I use a squeegee on inside glassing jobs, but I'm not very fond of the typical plastic ones. For almost 50 years I have been using slabs about 1/2" thick and typically maybe 4" x 6" or so, cut from blocks of ethafoam packing foam (like new TV sets and computer screens come packed in). Their semi-firm nature allows me to have enough force to get the cloth down tight to the surface and "comb" the surface down to a very uniform, resin-stingy weave pattern. PlusÖ.they're free. The most important thing to know on inside glassing is that if you are getting small spots where the cloth won't stay down against the wood, it is because they are under too much tension. You can stick them down over and over and they keep coming back. The way to fix them is to squeegee (or roll if you are using rollers) toward them and downward, into the hull, not up and out of it. Once you have nudged a sufficient amount of cloth toward the spot and reduced the tension, they will disappear. Never shut the door and walk away from any glassing job until the resin has stiffened up enough that things can't move due to unseen tension. Stay there while you can still fix them.

  12. #12
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    Default Re: Glassing bottom of wood boat?

    Thank you all for the tips and great information. Everything went well! I did initially apply a sealer coat of TotalBoat 2:1 epoxy, which was allowed to dry or cure. The sealer coat was sanded lightly. The 6oz. cloth was draped over the hull and roughly trimmed. The big difference for me was using TotalBoat 2:1 epoxy. In the past, I have used West System and Raka epoxy which were much thicker. The TotalBoat 2:1 epoxy is low viscosity which made wetting out the fiberglass cloth very easy. Todd's suggestion of using a foam roller to apply the epoxy was the only way to go. My brother Steve and my neighbor Steve Buonopane assisted me through the whole process. Later on during the day, I was able to apply another coat of epoxy to start filling the weave.
    IMG_1351.jpgIMG_1383.jpgIMG_9395.jpgIMG_1390.jpg
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  13. #13
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    Default Re: Glassing bottom of wood boat?

    Congratulations! You haven't been to hell until you glass the inside! everything that worked for you on the outside will be working against you on the inside!
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...0-Ducker-Resto

  14. #14
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    Default Re: Glassing bottom of wood boat?

    Looks good! I'm glad it came out well, I've never used totalboat but have heard good things. I see the telltale ring of drips on the floor...


  15. #15
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    Default Re: Glassing bottom of wood boat?

    The photos clear up my confusion as to the building technique, but since the modern thin-strip build **requires** fiberglass on both sides, I'm unclear why the question was asked in the first place.

    My Cosine Wherry is strip built, very nice and light and a joy to row -- but I can't imagine using it without the thin fiberglass both inside and out.




    Quote Originally Posted by Ian McColgin View Post
    I took bead and cove to mean that he's making a stripper, generally monocoque. Glass within and without is normal in that construction.

    The exact design is not mentioned but I'd bet the traditional peapod, a real crank to row unless loaded, has been pleasurized to make a good rowing boat. Rather than the traditional pod's heavy construction he's building light. It's a good advance.
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

  16. #16
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    Default Re: Glassing bottom of wood boat?

    That's a nice looking job. Glad to see you wore the right hat.

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