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Thread: Corking a boat

  1. #1
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    Question Corking a boat

    Hello:

    Quick question. My 71 Grand Banks with mahogany planking has been out of the water for 2 years. I put it in the water to soak up for a weekend in the straps, and the seams did start to close a little, but not enough to allow the boat to float. I had 7 pumps going putting out about 20,000 gallons an hour. I could tell the seams were getting narrower due to the fact that we were able to lower the boat every few hours, and were able to get it down to the water line.

    The question is when is it safe to add cotton to the seams as some of my cotton is missing (hence the flooding), and the red sealer on top of the cotton (i am assuming it is dried out Interlux 30) is hard as a rock, and should that be removed and replaced?

    I hear conflicting stories and it seams like there is a catch 22 sometimes. People build wood boats and the wood get dry and they cock the boat before it goes into the water. Other say don't cock a dry boat. At some time the boat has to get cocked as people can't put a massive wooden boat in the water just to put it back out to put in cotton and seam sealer. Now I understand about putting too much cotton in, and forcing it in all the way until it comes out the back of the plank, but if you watched the caulking of Tally Ho, they put several layers of caulking in the boat to get her corked up and I think those planks were a bit dry.

    So what is right and what is a no no? These seams have to be address, and I can't just swell up the boat and then put in missing cotton. There must be a procedure to help a wooden boat with semi dry wood that has cotton missing in some of the planks.

    Peace and thank you for your time in this matter.

  2. #2
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    Default Re: Corking a boat

    Welcome to the Forum.
    Tally Ho is a new build, with thick planking compared to most affordable yachts. So being a new build the inside of the planks were tight-fitting, and she could be caulked hard. The planks are so thick that it takes several passes to fill the seam.
    In your case, swell her up as much as she can, then re-caulk where the cotton is missing. You will have to remove the stopping on each end of the missing cotton so that you can ensure that there are no gaps.
    If the swelling does not tighten up the stopping, rake that out, harden up all the caulking cotton, prime it and refill the seams with stopping.

    Or hire a professional caulker.
    It really is quite difficult to build an ugly wooden boat.

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  3. #3
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    Default Re: Corking a boat

    hire a pro, one who does not say "corking" .

  4. #4
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    Default Re: Corking a boat

    Not helpful
    Quote Originally Posted by wizbang 13 View Post
    hire a pro, one who does not say "corking" .

  5. #5
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    Default Re: Corking a boat

    Quote Originally Posted by Sneezy View Post
    Not helpful
    which part?
    Two years stored should not create such a leaky launching.
    Is the 50 year old caulking still in there?

  6. #6
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    Default Re: Corking a boat

    But it is, really. How many boats have you caulked? When was the last time you caulked a boat? Do you have irons and a mallet and do you know how to properly roll cotton?
    There's a few things that are best left to the pros and caulking is one of them. How many other things will you do to your boat that have the potential for serious failure and then sinking the boat?
    Knowing how to do it and actually being good at it are two different things and I wouldnt bet my life or my boat on what I learned in a YouTube video.

  7. #7
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    Default Re: Corking a boat

    You can probably teach yourself to caulk your boat, I did. I don't think that I can explain in a forum post, but there are articles and probably videos that can help. Study and practice. Good luck, keep us posted.

  8. #8
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    Default Re: Corking a boat

    Quote Originally Posted by wizbang 13 View Post
    hire a pro, one who does not say "corking" .
    Bruce is mostly right, except that some of the best caulkers I know say corking. In particular a lot of the Seattle union guys call it corking. In particular one of the best west coast caulkers calls it corking, but he's from the eastern side of the mountains and also herds cattle. That all said Grand Banks can be tricky because depending when they were built some of them don't have true caulking seams but instead have planks that had cotton laid along them and then the next plank edge set hard against it, it can make it very tricky to caulk. In this style of construction there often is no true caulking seam so it makes life way harder. If it were my boat/ or a boat I had been hired to fix I would staple burlap to the entire hull below the waterline while she was out of the water and soak it, Probably for about a week. but potentially for way longer. After that I'd take a good look at how things had swelled then make a plan for caulking. Its still doable to caulk open square seams but its a tricky bastard.

    Nicholas

  9. #9
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    Default Re: Corking a boat

    Quote Originally Posted by Sneezy View Post
    Not helpful
    You'll have to forgive wiz. Someone must have p!ssed in his cornflakes a while ago since he has made nothing but
    snide remarks lately.

    Corking or caulking, it's all the same to me as I don't know much about it.
    Follow the friendly, helpful advice here and just remember that YouTube is your friend.
    Good luck with it.
    I was born on a wooden boat that I built myself.
    Skiing is the next best thing to having wings.

  10. #10
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    Default Re: Corking a boat

    You simply state that your boat is a Grand Banks. What size? Have you owned it for a while and are aware of it's
    "past leak history" and general condition?
    If it's a very large vessel, a pro might be the route to take for peace of mind.
    I was born on a wooden boat that I built myself.
    Skiing is the next best thing to having wings.

  11. #11
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    Default Re: Corking a boat

    Hello:
    Thanks for the replies. This is a Grand Banks 42 with 1 1/4" planking. Looking at the seams, I don't believe these are square seams, but tapered with the exception of about the first 1/4" or so on the inside of the hull. Right now some of the seams have about a popsicle stick thickness gap on the inside. Some of the original cotton is missing because it simply fell out after being compressed for the last 50 years and the seams can't hold it in due to drying. Frankly, hiring a professional is just not as easy as it sounds, especially if there are no wood boat professionals in that town. I would like to hire someone to give me some pointers, but at the moment, that is not possible. I have all of the proper tools, I am just asking others, in general, how tight the seams should be to safely add some cotton. The seam sealer does not harden, but remains flexible and can ooze out. The last owner use slick seam, but that is no longer available. Everyone that knows the boat says that it does not really leak at all once swelled up. I can't soak this boat for a week in the slings and the gaps with missing cotton have to be address if I have any chance of getting it to float on it's own until the wood can fully swell, which should take at least a week.

    Peace.

  12. #12
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    Default Re: Corking a boat

    I thought this suggestion(Post #8) on how to get your hull to swell up without having to hang it in the slings for a week seemed good.
    I've heard of other people doing it

    "If it were my boat/ or a boat I had been hired to fix I would staple burlap to the entire hull below the waterline while she was out of the water and soak it, Probably for about a week. but potentially for way longer. After that I'd take a good look at how things had swelled then make a plan for caulking."

  13. #13
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    Default Re: Corking a boat

    Quote Originally Posted by Rich Jones View Post
    You'll have to forgive wiz. Someone must have p!ssed in his cornflakes a while ago since he has made nothing but
    snide remarks lately.

    Corking or caulking, it's all the same to me as I don't know much about it.
    Follow the friendly, helpful advice here and just remember that YouTube is your friend.
    Good luck with it.
    I liked Bruce's comment. straight and to the point and damn right truthful.
    yes his responses are rather curt at times but generally on point.

    YouTube is not a good place to start learning about caulking...

  14. #14
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    Default Re: Corking a boat

    Quote Originally Posted by Pelirrojo View Post
    Bruce is mostly right, except that some of the best caulkers I know say corking. In particular a lot of the Seattle union guys call it corking. In particular one of the best west coast caulkers calls it corking, but he's from the eastern side of the mountains and also herds cattle.

    Nicholas
    Yes, well, they are US citizens. That lot can't even spell English correctly, let alone speak it.
    It really is quite difficult to build an ugly wooden boat.

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  15. #15
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    Default Re: Corking a boat

    Quote Originally Posted by Peerie Maa View Post
    Yes, well, they are US citizens. That lot can't even spell English correctly, let alone speak it.
    We don't speak English, we talk American (dialect).
    Steamboat

    I get by with the judicious use of serendipity.

  16. #16
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    Default Re: Corking a boat

    I liked Leo's point in the Tally Ho video that "caulking" and "corking" sound about the same in his accent. I will note that the guy who led that project definitely knows what he's doing and pronounces it "corking."

    Sneezy, what's your comfort level with experimentation? Corking is the kind of project where you can do major damage to your boat if things go wrong (e.g. ruined planking or cracked ribs). You would be well advised to hire someone to do it for you, or teach you.

  17. #17
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    Default Re: Corking a boat

    Quote Originally Posted by Sneezy View Post
    I can't soak this boat for a week in the slings and the gaps with missing cotton have to be address if I have any chance of getting it to float on it's own until the wood can fully swell, which should take at least a week.

    Peace.
    There have been a few threads on here about getting planks to swell back up after extended stays on the hard. The wet burlap idea is new but makes sense, I also remember reading about draping tarps around the hull and spreading wet sawdust on the ground to create a high-humidity environment. I remember watching a long planking process where at the end of each day the carpenters misted the hull with water from a garden sprayer to help keep the moisture level up in the wood. Could you put a catch basin under the boat, rig some lawn sprinklers to a sump pump and just let the system spray the hull until the seams take up?

    It makes sense to me that you would want to swell the planks before re-caulking.
    Steve

    If you would have a good boat, be a good guy when you build her - honest, careful, patient, strong.
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  18. #18
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    Default Re: Corking a boat

    I think it wouldn't bother me at all to hear someone pronounce caulking as corking. But to see caulking written as corking kind of makes me cringe. This discomfort extends to most attempts that modify the way words are written in order to lend a degree of colloquial pronunciation. Far better, in my view, to spell correctly in one's chosen language.

    Jeff

  19. #19
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    Default Re: Corking a boat

    Locally what we do to swell a hull is to tent the hull from the waterline down to the ground. Then we spray water under the tenting to raise the humidity under the boat. If possible garden soaker hoses work well if you have some place for excess water to go. For my boat (33') I didn't have running water so I just dumped 10-15 gallons of water under the boat 2-3 times a day. My boat was on gravel over dirt. I generally kept the swelling operation going for 3-5 days after a winter in the shed. I also dumped water in the bilge, but not a lot. My boat had shallow bilges so 15 gallons was about all I could put in the bilges. We haul out over the winter here in Maine so this was an every year thing for the 11 years I had my boat in the water. I sold it last April.
    Last edited by Todd D; 09-21-2022 at 11:17 AM.

  20. #20
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    Default Re: Corking a boat

    How well did this work? Was 3-5 days enough?

    Quote Originally Posted by Todd D View Post
    Locally what we do to swell a hull is to tent the hull from the waterline down to the ground. Then we spray water under the tenting to raise the humidity under the boat. If possible garden soaker hoses work well if you have some place for excess water to go. For my boat (33') I didn't have running water so I just dumped 10-15 gallons of water under the boat 2-3 times a day. My boat was on gravel over dirt. I generally kept the swelling operation going for 3-5 days after a winter in the shed. I also dumped water in the bilge, but not a lot. My boat had shallow bilges so 15 gallons was about all I could put in the bilges. We haul out over the winter here in Maine so this was an every year thing for the 11 years I had my boat in the water. I sold it last April.

  21. #21
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    Default Re: Corking a boat

    It worked fine if the boat was just in the shed in cold storage.

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