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Thread: How to fix leaky plywood construction?

  1. #1
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    Default How to fix leaky plywood construction?

    So I found some leaks in my new to me 1950's plywood boat. Nothing drastic, but after a few hours, it is more than I'd like to see, so I'm going to roll my sleeves up and see if I can make it water tight

    This boat is painted pretty heavily on the inside and out. I don't think its glassed but who knows what lies beneath. The leak is at the transom area.

    I was thinking of removing the paint via heat gun and see what condition the wood and joints are in beneath the paint.

    If the wood seems solid, would it be acceptable practice to inject CPES into the joints and repaint? This is a day boat, dry stored

    Thanks in advance

  2. #2
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    Default Re: How to fix leaky plywood construction?

    Spin the paint off the suspect area .
    Take photos n post em.
    Injecting CPES is good for ply, but will probably not stop any leak. I see thickened regular epoxy in your future.
    Best to get her dry and keep her dry.

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    Default Re: How to fix leaky plywood construction?

    wizbang 13 is right. If the area is basically ok, CPES will be good for the wood and you should, but it's nowhere for the leaks. Given the leaks and the nature of plywood, I'd expect some rot. It sounds daunting but replacing a transom is not actually the biggest deal and would be actually easier than trying to scarf in lots of bits with strange shapes. A lot depends upon how much rot may have traveled forward on the hull.

    If it's not a soggy black and soft, you might get away with a good drying, CPES, and then glass tape the transom to hull join.

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    Default Re: How to fix leaky plywood construction?

    Wonderful, thanks for the info. I hope I don't have to replace the transom, but I think it's a project I'm comfortable with should it need it. It is a little lighter built than I like (I posted a thread about it recently)

    I will keep you posted

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    Default Re: How to fix leaky plywood construction?


    Planing boats from the fifties had to be light. A 40 hp was the biggest motor available in 1956.
    The quality of plywood was generally better than what we have today though.
    I hope that trailer is not hurting her.The rollers make hard points , and the winch pulling DOWN on the bow can make them even worse.

  6. #6
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    Default Re: How to fix leaky plywood construction?

    Quote Originally Posted by wizbang 13 View Post

    Planing boats from the fifties had to be light. A 40 hp was the biggest motor available in 1956.
    The quality of plywood was generally better than what we have today though.
    I hope that trailer is not hurting her.The rollers make hard points , and the winch pulling DOWN on the bow can make them even worse.
    Thanks WB, you found it... I am changing it to bunks this winter, or before I put the motor on it. I had heard the ply was better back then, here's hoping its still pretty decent under the paint - will keep you posted as to what I find

  7. #7
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    Default Re: How to fix leaky plywood construction?

    I started stripping paint off of the transom and rear corner. This boat was stripped and repainted once before. So far, the wood looks ok. The worst I've found underneath is that it appears that someone used a wire wheel on a grinder and dug into the wood in a few spots. What is a good product to level this out again so I can get a nice, smooth and glossy finish on it again?

    Also, what's a good photo hosting site to use now? Photobucket can pound salt...I'm done with them

  8. #8
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    Default Re: How to fix leaky plywood construction?

    Photos can be posted straight to the forum now and I would use microlight fairing filler and west system epoxy for the dings.
    -Jim

    Sucker for a pretty face.
    1934 27' Blanchard Cuiser ~ Amazon, Ex. Emalu
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    Getting into trouble one board at a time.

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    Default Re: How to fix leaky plywood construction?

    You will need to get rid of the moisture before putting in the CPES. This can be done by injecting alcohol into the wet wood and aiming a heat lamp at it till it is dry. Then inject the resin sealer.
    Jay

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    Default Re: How to fix leaky plywood construction?

    Thanks guys

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    Default Re: How to fix leaky plywood construction?

    Hey guys, I’ve stripped the paint off the bottom edge of the transom and the bottom edge. There’s a few localized dark and soft spots. What do you think? I had difficulty removing the original yellowish paint beneath the thick white topcoat. Do I need to remove it completely? It’s tough as hell.
    Last edited by ShoestringMariner; 04-03-2018 at 07:19 PM.

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    Default Re: How to fix leaky plywood construction?

    Last edited by ShoestringMariner; 04-04-2018 at 05:22 AM.

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    Default Re: How to fix leaky plywood construction?

    Attachment 13597Attachment 13598Attachment 13599

    Sorry, struggling with photo uploads

    Wondering if I can get away with CPES and stripping in a small band of fibreglass along the bottom edge, followed by fairing & painting?
    Last edited by ShoestringMariner; 04-03-2018 at 07:32 PM.

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    Default Re: How to fix leaky plywood construction?

    The old school answer would be to fix it right the first time. If CPES works as advertised you will probably be ok. Try it and see how many years it lasts.

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    Default Re: How to fix leaky plywood construction?

    Photos that we can see would help us to help you.

  16. #16
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    Default Re: How to fix leaky plywood construction?

    Quote Originally Posted by wizbang 13 View Post
    Photos that we can see would help us to help you.
    Weird, at first they were displayed in the message pane and shortly afterwards they changed to clickable links. Now they dont work at all. Not sure what gives, but you are entirely right.

    Im still steamed with photobucket for trying to put us over the barrel. I hope they go out of business.

  17. #17
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    Default Re: How to fix leaky plywood construction?

    Let’s try this againAttachment 13641

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    Default Re: How to fix leaky plywood construction?


  19. #19
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    Default Re: How to fix leaky plywood construction?


  20. #20
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    Default Re: How to fix leaky plywood construction?

    484025EF-3CA3-4D69-AC15-8B645C6D7BB9.jpg
    Quote Originally Posted by wizbang 13 View Post
    Photos that we can see would help us to help you.

  21. #21
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    Default Re: How to fix leaky plywood construction?

    So they uploaded again same as before. Loud and clear, visible in the message pane. As I upload more, they start showing up as clickable attachments.hope they stay working

  22. #22
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    Default Re: How to fix leaky plywood construction?

    Ok , I see a pic in #20. The fir ply looks fine. Is it buggered up on the inside? That is where I might expect to find trouble . Also, were it me, Id take all the paint off the area , and maybe the plywood piece with the grain running vertically to hold the ob. Is it glued on , bedded and screwed?
    But so far, it looks fine.

  23. #23
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    Default Re: How to fix leaky plywood construction?

    I agree. Check the inner plys but you might be lucky. At least get off all the scaley paint inside and out. I see nothing wrong with some white laying in valleys between exposed raw but you want most of the paint gone.

    Then CPES inside and out as a preservative. Pay special attention to soaking in at panel edges and the chine logs. CPES is affectionatly called "weasel psss" for a reason. Work outside. And it causes cancer in rocks and death in anything. Have wind or a fan and properly rated filters in your mask.

    The CPES, as has been mentioned, is a penetrating sealer. It won't do squat for any gaps. For that job, check out Gluvit, which I've been using happily in this sort of application for a bood forty years. It's a bit flexable and finds its way into gaps which it fills. Gluvit takes a long while to cure so give it a week before washing the blush off, sanding, and painting. Exterior latex goes on just fine. Gluvit all over the outside and at least the inside bottom, chine logs, stem, and trasom. With all that, it's unlikely that you'll need fiberglass tape on the chines and such.

    G'luck

  24. #24
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    Default Re: How to fix leaky plywood construction?

    Quote Originally Posted by wizbang 13 View Post
    Ok , I see a pic in #20. The fir ply looks fine. Is it buggered up on the inside? That is where I might expect to find trouble . Also, we’re it me, I’d take all the paint off the area , and maybe the plywood piece with the grain running vertically to hold the ob. Is it glued on , bedded and screwed?
    But so far, it looks fine.
    11B9BDB0-5C6C-4E49-A805-927C9B30B57A.jpg00C1D288-7F59-4220-8D97-F734882B65C5.jpg

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    Default Re: How to fix leaky plywood construction?

    It’s doing it again except in #20. I wonder if this site thinks I’m spamming?

    in any case, I have not stripped any of the interior. I will try that tonight.

  26. #26
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    Default Re: How to fix leaky plywood construction?

    Quote Originally Posted by wizbang 13 View Post
    Ok , I see a pic in #20. The fir ply looks fine. Is it buggered up on the inside? That is where I might expect to find trouble . Also, we’re it me, I’d take all the paint off the area , and maybe the plywood piece with the grain running vertically to hold the ob. Is it glued on , bedded and screwed?
    But so far, it looks fine.
    It is screwed on, not sure if glued or bedded. I will try to pop it off. Thanks for the help

  27. #27
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    Default Re: How to fix leaky plywood construction?

    Quote Originally Posted by wizbang 13 View Post
    Ok , I see a pic in #20. The fir ply looks fine. Is it buggered up on the inside? That is where I might expect to find trouble . Also, we’re it me, I’d take all the paint off the area , and maybe the plywood piece with the grain running vertically to hold the ob. Is it glued on , bedded and screwed?
    But so far, it looks fine.
    0A44EA7D-0B9B-44AC-B3A4-1622E004B954.jpg326A2CFB-D7E0-465A-9272-8CCFE1EB46B8.jpg326A2CFB-D7E0-465A-9272-8CCFE1EB46B8.jpg
    Attached Images Attached Images

  28. #28
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    Default Re: How to fix leaky plywood construction?

    Quote Originally Posted by Ian McColgin View Post
    I agree. Check the inner plys but you might be lucky. At least get off all the scaley paint inside and out. I see nothing wrong with some white laying in valleys between exposed raw but you want most of the paint gone.

    Then CPES inside and out as a preservative. Pay special attention to soaking in at panel edges and the chine logs. CPES is affectionatly called "weasel psss" for a reason. Work outside. And it causes cancer in rocks and death in anything. Have wind or a fan and properly rated filters in your mask.

    The CPES, as has been mentioned, is a penetrating sealer. It won't do squat for any gaps. For that job, check out Gluvit, which I've been using happily in this sort of application for a bood forty years. It's a bit flexable and finds its way into gaps which it fills. Gluvit takes a long while to cure so give it a week before washing the blush off, sanding, and painting. Exterior latex goes on just fine. Gluvit all over the outside and at least the inside bottom, chine logs, stem, and trasom. With all that, it's unlikely that you'll need fiberglass tape on the chines and such.

    G'luck
    Wonderful, thanks so much. I appreciate the safety tips, that CPES sounds NASTY.

    I just read about gluvit on some aluminum boat threads. I will need some for my fishing boat, so I will try that instead.

    Thanks again

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    Default Re: How to fix leaky plywood construction?


  30. #30
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    Default Re: How to fix leaky plywood construction?



    Not to horn in on the excellent advice you are getting from Bruce and Ian, but the area in the lower left looks suspect for rot to me.

    Why did the builder run the stringers through the transom like that? I'll happily stand corrected, but until then, I don't think its a good practice and I'll bet that is where your leak ir originating.

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  31. #31
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    Default Re: How to fix leaky plywood construction?

    Have you tried tapping with a small hammer on the suspect areas and comparing the resonance to wood that you know is good. If the core is rotten it will give off a dull dead sound.
    Jay

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    Default Re: How to fix leaky plywood construction?

    Good point, Breakaway. That's just the sort of problem that could turn a cost-effective restoration into something more expensive and more difficult than just building a boat anew.

    Get her scarped and really really evaluate.

  33. #33
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    Default Re: How to fix leaky plywood construction?

    Hey guys, do you see any concerns with this boat being supported upside down on 4 or 6” wide carpet slings? Sorry for the poor photo. Took all the pictures off my phone except this one. It’s a dual cockpit hull without a walk through. Solid plywood seat back. Should be ok, no?
    51249039-CC2B-4FFF-A806-79D4C8371156.jpg

  34. #34
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    Default Re: How to fix leaky plywood construction?

    I do not see a problem with her being upside down supported by straps.
    I might want to put bunks on the trailer that support the actual transom though.
    Plywood boats are very susceptible to dents from rollers, these dents can create a suction cup at high speed, creating annoying and sometimes dangerous effects. Hard steering,nose diving in turns,stuff like that.

  35. #35
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    Default Re: How to fix leaky plywood construction?

    Quote Originally Posted by wizbang 13 View Post
    I do not see a problem with her being upside down supported by straps.
    I might want to put bunks on the trailer that support the actual transom though.
    Plywood boats are very susceptible to dents from rollers, these dents can create a suction cup at high speed, creating annoying and sometimes dangerous effects. Hard steering,nose diving in turns,stuff like that.
    Perfect, thank you. I was concerned there may not be enough support or negative strain on the hull. It’s only quarter inch thick

    The boat is no longer on this trailer. I have put it on a smaller trailer with keel rollers and bunks. My fishing boat now sits on this trailer

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