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Thread: Thoughts on caulking alternatives

  1. #36
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    Default Re: Thoughts on caulking alternatives

    You don't think filling the seams with 5200 will "add tension, strength and resilience to the entire hull structure" once the planks swell a bit? I do. It will become a one piece hull. That will spread any stresses over a greater area. So long as the seams are narrow flexion will be next to nothing, and repeated flexion will not work the caulking out of the joints.

  2. #37
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    Default Re: Thoughts on caulking alternatives

    I don't think the planks will move when glued to each other and the frames with 5200 or another very strong sealant. I'm interested to see how it goes.

  3. #38
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    Default Re: Thoughts on caulking alternatives

    Quote Originally Posted by Gib Etheridge View Post
    You don't think filling the seams with 5200 will "add tension, strength and resilience to the entire hull structure" once the planks swell a bit? I do. It will become a one piece hull. That will spread any stresses over a greater area. So long as the seams are narrow flexion will be next to nothing, and repeated flexion will not work the caulking out of the joints.
    It will add resilience in the one place where we do not want resilience.
    3Mô Marine Adhesive Sealant 5200 is designed to meet the high demands of the marine environment, making it ideal for creating tough bonds resistant to saltwater and weathering. We formulated our sealant to provide an exceptionally strong solution for marine conditions as well as flexibility that combats vibrations, swelling, shrinking or shock.
    and
    Elongation >700 Percent, >800 Percent
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  4. #39
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    Default Re: Thoughts on caulking alternatives

    Nick,

    Just because it can elongate 800% doesn't mean that it will. I seriously doubt that a narrow seam 49' long filled with 5200 will allow any more slippage in shear than any fibrous material, and once the fibrous material starts to slip it will only get worse., a slippery slope if you ask me. The ability to stretch may very well make it a better method since it won't work it's way out.

    Kind of hard to tell though, isn't it?

    Until someone has proven the superiority of one over the other there's not really much point in arguing the matter.

  5. #40
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    Default Re: Thoughts on caulking alternatives

    Quote Originally Posted by Gib Etheridge View Post
    Nick,

    Just because it can elongate 800% doesn't mean that it will. I seriously doubt that a narrow seam 49' long filled with 5200 will allow any more slippage in shear than any fibrous material, and once the fibrous material starts to slip it will only get worse., a slippery slope if you ask me. The ability to stretch may very well make it a better method since it won't work it's way out.

    Kind of hard to tell though, isn't it?

    Until someone has proven the superiority of one over the other there's not really much point in arguing the matter.
    Gib, you do not want those planks moving AT ALL. If they do the plank to frame fastenings will wear and the hull will turn into a basket case. The cauklling has to resist sheering forces without allowing any movement. That is why big high class yachts were fitted with diagonal strapping, to help the caulking resist those shear forces.
    If the "fibrous materiel starts to slip" you haul the boat and recaulk her.
    It really is quite difficult to build an ugly wooden boat.

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  6. #41
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    Default Re: Thoughts on caulking alternatives

    Thank you Gill. On the insurance note, I hired a reputable surveyor who has specialized in wood boats in the past. In fact he owned a wood Alaskan 20 years ago. He has been by to make progressive picture documentation as we have replaced a lot of the planking so he could see the shape of the structure underneath. He said he would have no issues with the method I am prescribing and agreed that it would probably make the boat stronger.

    I have been looking into insurance and have found that only a few are willing to write insurance on a wood boat at all. The companies that I got quotes from only asked for a recent survey. For those who are worried about me taking it to sea, I simply won't invite you out on my boat. So you have nothing to worry about.

  7. #42
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    Default Re: Thoughts on caulking alternatives

    I'm going with Nick here. And Gerry, you have obviously made up your mind so I'm doing this merely as an intellectual exercise. But to this point...

    I seriously doubt that a narrow seam 49' long filled with 5200 will allow any more slippage in shear than any fibrous material,
    Gib, I really don't think you are considering the hull as a complete structure here. The issue is not "slippage in shear" within a single seam. It's transfer of shear loads between the planks and ultimately to the keel or the sheer clamp and deck structure. Imagine the forces on the entire hull as it rolls, for example. Each plank, as a discrete part, wants to move independently. If that happens then *all* of the forces are transferred to the fasteners as shear loads. Which they are not designed to withstand. So the forces on the hull need to be transferred from each plank to the next and ultimately to the keel or the sheer clamp and deck structure, which then take the loads in compression rather than shear.

    Cotton caulking is flexible but that is only part of the story. When it is compressed by the caulking mallet it tightens to the point where it will take the shear loads and transfer them to the next plank. Thus the "ringing" that Jay pointed out above. That's significant not as some arcane "caulking by ear" measure, but because ringing means that vibrations are being transferred throughout the hull - i.e. it is operating as a single structure in response to a force applied to it (in this case the tapping of the mallet). 5200 might not move *very much* in a given seam. But multiplied over all the seams in the hull even a little flex becomes a significant factor.

    But at a certain point all of this is hypothetical. Jay, Nick and other professionals know that caulking will work so that is what they will recommend. Is it possible that 5200 or some slurry of glue and sawdust could work equally well? Perhaps. I doubt it, but no one knows for sure because no one has done a valid trial of the approach. I'd be VERY interested in seeing that done, but simply slapping some goop into the seams of a big boat and seeing whether she floats ain't that. Not even close.
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  8. #43
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    Default Re: Thoughts on caulking alternatives

    Certainly a mind decided is a mind made up, so I'm not going to try to sway anyone.

    However, I will speak from experience on the 'tightening and stiffening' aspect of a proper traditional caulking job. when I rebuilt my cockpit sole (~ 10' x 10') and relayed the original teak it was quite spingy with the teak fastened in place. As I caulked the sole and drove the cotton into the seams (thank you for whoever it was that made the first correction here, .. cotton is "driven" not "pounded") it was amazing how much the sole stiffened and tightened up. It went from feeling like stepping on springy individual planks to feeling very much like walking on a concrete sidewalk. No movement at all.


  9. #44
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    Default Re: Thoughts on caulking alternatives

    Again thank you all for the input. It is not my intentions to "slap" goo and hope for the best. I would like to document what I am doing and then test it out over the next few years. Here are the pics of the bottom seams and the watering system that I will use to get the planks to swell to the right moisture content. I am not committed to 5200 if there is another product that would work better. I am looking for adhesion properties with an exposed surface that holds paint. If anyone is interested in following this process, private message me and we can talk about it. I think this thread should end here. Thanks again for your interest.

    Gerry
    20170702_191207.jpg20170526_083903.jpg20170120_140848.jpg20170121_095216.jpg

  10. #45
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    Default Re: Thoughts on caulking alternatives

    Having worked with both Italian and Swedish tight seam planking, splined seams and traditional driven cotton caulking, and double planking there are only two I would choose for my own boat. Double planking requires no caulking, when done correctly. It is messy and time consuming but very effective in producing a tight strong hull. But, it is hell to repair if damaged.
    My all time favorite is driven cotton cotton!
    Jay

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