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Thread: Thoughts on caulking alternatives

  1. #1
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    Default Thoughts on caulking alternatives

    I am at the final stages of a major restoration project on a 1973 49' Grand Banks Alaskan and have to make a decision on caulking the bottom. The boat is in a yard in Saint Pete Florida and I cannot find anyone who does conventional cotton caulking and have been looking into alternatives.

    A couple of notes. The boat has been out of the water for over a year and after the initial wood shrinkage all of the seams opened up and allowed me to reef all materials out of them. The prior owner used 5200 as seam material and as one expects it pulled the wood off the sides of the seams in some places. Having spent days using a razor blade, I was able to clean them up somewhat. I developed a hatred for the stuff. There were three plank replacements I inherited, that used only 5200 (no cotton) and they will have to be cut out with a blade to replace them.

    My initial distaste for 5200 has come full circle though. The replaced planks look like they are good for life and I started looking at that as an alternative to cotton caulking.

    So without starting a word war of traditional methods I would like to know if anyone has tried using a modern sealant/adhesive as the only caulking? I would like to propose something different. This is what I am thinking.
    1. Use a dado blade and/or a router to cut a consistent width seam, taking out the bevel.
    2. Inserting a really thin strip of softwood at the stringers to minimize caulk intrusion into the boat.
    3. After priming, fill the entire seam with a 5200 like product.
    4. Water the hull inside and out to get to the proper moisture content.
    5. Trim off excess proud material to get a flat paintable surface for bottom pain.

    The pros of this method are
    1. It is a permanent waterproof hull with wood continuing to be in contact with the water.
    2. Plank separation due to fastener failures would not be a critical issue as each plank is "glued" to the one above and below.
    3. In worm infested waters the likeliest infestations take place in the seam where conventional caulking fails.
    4. Does not rely on a "soon to be lost" skill set of cotton caulking. Can be a DYI project.

    The cons would be
    1. The seams are somewhat permanent. In the case of a plank failure you would have to cut it out with a circular saw and plunge cutter in order to replace it.
    2. Timing of installation with wood swelling and curing time could cause a squeeze that might break fasteners.
    3. The time that the boat is out of the water and the drying shrinking process would have to be watched to avoid letting the seams open up enough for the bond to break.

    I have been looking on the forums and the internet but have not found anyone doing this. Am I missing a big issue? Positive feedback would be appreciated.

    Gerry


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    Default Re: Thoughts on caulking alternatives

    When I replanked after repairing lots of framing, I use Loctite PL premium polyurethane construction adhesive in the seams, mixed with about 30% sawdust, this was back in 2006. It has ever come out of the seams, squeezed out, leaked in water, etc....
    Just mix on a board then trowel and force it into all the seams. Cotton caulking is pretty hard substance when packied into the seam, PL is I think somewhat similar hardness. Not soft and gooey, not like a rock.

    The 28oz cartridge is cheaper than buying 10oz.
    https://www.homedepot.com/p/Loctite-...0594/202020474

    In 2014 I skim coated Loctite Black PL roof flashing over the bottom to seal all the planking, and has held up fine underwater.

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    Default Re: Thoughts on caulking alternatives

    Did you have cotton in the seam before the PL?

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    Default Re: Thoughts on caulking alternatives

    I wonder if the PL/sawdust mix would be easier to apply with one of these refillable caulking tubes.
    https://www.westsystem.com/applicati...aulking-tubes/

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    Default Re: Thoughts on caulking alternatives

    Caulking with a fibre like cotton or oakum is not just waterproofing, but serves a structural purpose as well locking the planks together by conpression.
    If you don't want to caulk, glue in softwood splines.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Thoughts on caulking alternatives

    I'm not going to join in a war over caulking here, but Gerry, this topic has been well covered here over the years. The problem with all of the "modern alternatives" is that caulking is not done just to seal the seams. It is a structural element in the boat that, among other things, relieves shear forces on the fasteners, reduces the amount of movement in the planks and is generally one of the main factors in preserving the structural integrity of the hull. User sdowney717 is a proponent of goop over caulking and reports good results so far. But ten years is not even remotely a useful longevity test, and simply reporting that the hull does not leak does not indicate anything about the long-term value of that approach.

    An Alaskan is a big, valuable boat intended for extended cruising. There is absolutely no way that any knowledgeable expert would recommend anything other than a professional caulking job for her and there is no way you would get me to go to sea in one that had not been done properly. The risk to your wallet and your life - saying nothing of the lives of anyone you might take with you - is simply not worth the experiment.

    That said, I am no luddite and I would welcome a well-controlled test of any modern solution that addressed both the structural requirements and the sealing requirements. My bet is that any such technique would require a substrate with limited compressibility, to provide strength and sealing, behind a softer compound designed to support a paint layer while remaining compressible to account for plank swelling. And given the unpredictable and variable amount of swelling and the variable width of seams, etc. any such product would likely have to be applied by a technician with sufficient experience to gauge the right amount of pre-compression applied to the substrate in order to ensure a proper seal without causing damage by overcompression after swelling.

    If that sounds an awful lot like traditional caulking, well then I think you have your answer.
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    Default Re: Thoughts on caulking alternatives

    Nick is absolutely correct concerning the added structural integrity that is the result of caulking with either cotton or oakum.
    A hull will begin to ring like a bell as the planking takes up during the driving of the caulking.
    Jay

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    Default Re: Thoughts on caulking alternatives

    Quote Originally Posted by gbroughman View Post
    Did you have cotton in the seam before the PL?
    Nope, I had zero cotton, just wood edges.

    The PL and sawdust mix adds stiffness just as it will using cotton. The glue also expands as it cures, so it fully seals and conforms to the edges tight as a form fitting glove plank edge to plank edge, yet will have a slight give and springback to it if compressed.

    I filled some good sized gaps between some planks, I did this in July heat, so the planks were good and dry.

    I also filled the bung holes with that mixture. Simply sand it down or you can cut it with a knife.

    I remember now, one plank edge on the bottom had shrunk to a full 1/2 inch gap. But see I was putting planks back on and that is where it ended up as the last plank in sort of. Anyway, I cut a thin 3/8 or 1/4 inch filler strip and glued it in with the glue, and that worked very well then and still is today.
    Last edited by sdowney717; 12-06-2017 at 03:01 PM.

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    Default Re: Thoughts on caulking alternatives

    Sdowney717, I think it would be accurate to say "In theory the PL and sawdust mix adds stiffness just as it will using cotton". I appreciate your confidence in your solution and I'm not trying to start a battle over it at all, but the fact is that traditional caulking has been tested over hundreds of years and many thousands of boats in the most extreme conditions. Your solution is a test case of one and we don't have any knowledge of the conditions it has been exposed to. No one knows what will happen to a boat caulked in that manner over the long term or in very bad weather. Will it work excessively and put additional strain on fastenings? We don't know, and with all due respect, you don't either.
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    Default Re: Thoughts on caulking alternatives

    Quote Originally Posted by cstevens View Post
    Sdowney717, I think it would be accurate to say "In theory the PL and sawdust mix adds stiffness just as it will using cotton". I appreciate your confidence in your solution and I'm not trying to start a battle over it at all, but the fact is that traditional caulking has been tested over hundreds of years and many thousands of boats in the most extreme conditions. Your solution is a test case of one and we don't have any knowledge of the conditions it has been exposed to. No one knows what will happen to a boat caulked in that manner over the long term or in very bad weather. Will it work excessively and put additional strain on fastenings? We don't know, and with all due respect, you don't either.
    Yes, cant compare pounded cotton to a product which has only been around a few decades, be unreasonable to say otherwise. I have very good experience using it. I certainly have bought hundreds of tubes of that stuff and used it just about on everything. I even repaired the rust holes in my 1994 station wagon using that glues and some aluminum sheet metal and some thick fiberglass cloth saturated with PL, and some screws. That was a very successful repair.

    I dont show the sanded down final repair in this album

    https://goo.gl/photos/caNjzr6zbA7bFoRk9
    Last edited by sdowney717; 12-06-2017 at 03:17 PM.

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    Default Re: Thoughts on caulking alternatives

    Quote Originally Posted by sdowney717 View Post
    Yes, cant compare pounded cotton to a product which has only been around a few decades, be unreasonable to say otherwise. I have very good experience using it. I certainly have bought hundreds of tubes of that stuff and used it just about one everything. I even repaired the rust holes in my 1994 station wagon using that glues and some aluminum sheet metal and some thick fiberglass cloth saturated with PL, and some screws. That was a very successful repair.

    I dont show the sanded down final repair in this album

    https://goo.gl/photos/caNjzr6zbA7bFoRk9
    Trouble is if it allows the seams to flex, and the boat to work, sometime down the line you will have to replace every plank fastening with a larger gauge to cure the boats working due to the fastenings fretting the wood and coming loose.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Thoughts on caulking alternatives

    Quote Originally Posted by sdowney717 View Post
    Yes, cant compare pounded cotton to a product which has only been around a few decades, be unreasonable to say otherwise. I have very good experience using it. I certainly have bought hundreds of tubes of that stuff and used it just about on everything. I even repaired the rust holes in my 1994 station wagon using that glues and some aluminum sheet metal and some thick fiberglass cloth saturated with PL, and some screws. That was a very successful repair.

    I dont show the sanded down final repair in this album

    https://goo.gl/photos/caNjzr6zbA7bFoRk9
    Sure, and like I said, I'm not trying to debate the potential value of your solution. I would love to see it, or some variation, validated through a controlled trial. I'm not at all against the idea of a modern alternative to caulking. But when a guy shows up with something like an Alaskan I think prudence would argue for the proven solution. An Alaskan is a big, heavy displacement boat designed for long distance cruising. Maybe Gerry will park it in a slip and use it as a party pad, I don't know. But somewhere down the line someone might try to use it for its intended purpose and personally I'd like to think that the planks will be supported by traditional, well-proven cotton and oakum caulking when that owner - or perhaps that family - is taking her offshore.
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    Default Re: Thoughts on caulking alternatives

    Quote Originally Posted by Peerie Maa View Post
    Trouble is if it allows the seams to flex, and the boat to work, sometime down the line you will have to replace every plank fastening with a larger gauge to cure the boats working due to the fastenings fretting the wood and coming loose.
    It is truly just as stiff as cotton, so it does not work. My planks dont flex or bend around in the sea between their plank edges, I have even felt the bottom in rough water, it is solid, like an engineered wood structure. Personally I think it is better than cotton. The boat also does not need to take up, splash it and it is dry.

    If you put soft thing like 5200 in there that can work I suppose which is why it wants come out of the seams.

    This glue is a lot better than some want to give credit for.
    Last edited by sdowney717; 12-06-2017 at 03:35 PM.

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    Default Re: Thoughts on caulking alternatives

    And for the OP - aren't you glad you asked?
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    Default Re: Thoughts on caulking alternatives

    Another seriously good product for above waterline seams is DAP Dynaflex 230.
    It is permanently flexible seal.
    http://www.dap.com/dap-products-ph/d...tdoor-sealant/

    I pulled the failing cracking linseed oil putty and all cotton threads out of my topside planks, and filled with DAP caulk. That removal of the old dried putty was not very easy, lots of seams to rework.

    When it is fully dry, this is like a very hard rubber. It keeps water out from between the planks which in my case was causing plank edges to rot.
    The DAP will shrink which I actually liked as it defined every plank edge perfectly.
    I then primed the planks with Zinsser Bulls eye latex primer and painted on top with gloss acrylic latex whit paint.

    https://www.rustoleum.com/product-ca...er-base-primer

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    Default Re: Thoughts on caulking alternatives

    Gather your traditional materials, prep the bottom, find a professional caulker, put him on a plane to wherever you are, and let him at it. He'll work for 2 days and it'll be done properly, and good for 20 years.

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    Default Re: Thoughts on caulking alternatives

    It won't be until you are out in heavy weather that you really worry about it. Perhaps if you were to add a couple of additional fasteners in each plank at each frame you won't worry so much. Too many fasteners is not a good thing though, so what else could one do? How about some form of diagonal bracing inside of the planking, perhaps between the frames? Or how about the ultimate diagonal bracing, 2 layers of double diagonal cold molding on the outside? Wooding, splining and cold molding over a nice dry hull has proven to be a very effective alternative to caulking, and in the long run requires much less in the way of maintenance, and it won't leak.

    Not advising anything, just a few thoughts.

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    Default Re: Thoughts on caulking alternatives

    I wonder if instead of splining using caulk between the planks before cold molding over would work. I bet it would, especially if there were a layer of moderately heavy glass cloth between the layers.

    Lotta work, but only once, and not really difficult, and once you get in the groove it moves along OK. It's the kind of job where you can employ an unskilled and therefore affordable helper.

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    Default Re: Thoughts on caulking alternatives

    Quote Originally Posted by outofthenorm View Post
    Gather your traditional materials, prep the bottom, find a professional caulker, put him on a plane to wherever you are, and let him at it. He'll work for 2 days and it'll be done properly, and good for 20 years.

    ^^^ Yes. This. Although I think 2 days is optimistic for a 50' Alaskan. I can recommend a caulker if you need one. The main point is that maybe other approaches would work for a short term. Maybe they would work forever. But on an offshore crossing to the Bahamas with the wind picking up and the waves building and the nearest shelter still hours away, do you want to be wondering about it? I definitely wouldn't.
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    Default Re: Thoughts on caulking alternatives

    Quote Originally Posted by Gib Etheridge View Post
    I wonder if instead of splining using caulk between the planks before cold molding over would work. I bet it would, especially if there were a layer of moderately heavy glass cloth between the layers.

    Lotta work, but only once, and not really difficult, and once you get in the groove it moves along OK. It's the kind of job where you can employ an unskilled and therefore affordable helper.
    Ever seen this?


    Using this here

    I mixed in milled fibers to this waterproof caulk at 30% fiber to 70% caulk.
    The resultant mix was easy to trowel on and smoothout with a 6 inch putty knife and is very strong, yet flexible, waterproof and gribble and worm proof barrier.
    Has been on the hull now since 2014 with no failures.

    I esitmate the surface thickness to be from 1/16 to 1/8. It took me about 250 tubes I think for the entire bottom.
    Parts I wooded, other parts I simply plastered over the yellow permaflex.







    Last edited by sdowney717; 12-06-2017 at 04:17 PM.

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    Default Re: Thoughts on caulking alternatives

    Yes, I have been watching your updates. I love new ideas and congratulate you on your entrepreneurism, for lack of a better word. You may have put together the way of the future. I hope so.

    What material are the fibers?

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    Default Re: Thoughts on caulking alternatives

    Quote Originally Posted by Gib Etheridge View Post
    Yes, I have been watching your updates. I love new ideas and congratulate you on your entrepreneurism, for lack of a better word. You may have put together the way of the future. I hope so.

    What material are the fibers?
    These are ground fiberglass fibers.

    You can actually fairly easily smooth the rubber when mixed with the glass fibers.

    One way to smooth which is easy, use a rotary brush on the drill.
    I put the black pl with and without fibers on various parts of the hull. While both work, using the fibers added in is better. Added cost is negligible since you are stretching out the Loctite black pl to make it go further.

    I found with fibers added, the rotary brush easily smooths the surface, without the fibers it does not.
    Anyway, it is just like frosting a cake. The black PL remains very sticky feeling for a few days. Takes about 4 days to cure fully or maybe a full week depends on humidity and temp.

    And for filling any gaps, mix in shredded cotton even from cotton balls into black pl, works great to fill seams.

    That yellow permaflex was ok since 2006, but it did not stick to my oak keel, stuck fine everywhere else. So I ripped it off the keel, was form fitted just like a glove. And so then experimented with the black PL from Loctite, first on the keel , then elsewhere.
    Last edited by sdowney717; 12-06-2017 at 04:38 PM.

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    Default Re: Thoughts on caulking alternatives

    Is this the type of brush you used?

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    Default Re: Thoughts on caulking alternatives

    I once saw a professional boatbuilder in Nova Scotia troweling a mix of PL Premium (or similar) and sawdust into the seams of an old powerboat. The boat was modest size, probably less than 20', the man with the trowel was named Heisler, IIRC. He was a character, but very experienced, and assured me that the method was sound. I don't remember what use or life was intended for the boat.
    Traditional cotton caulking isn't terribly hard, I learned it from articles and pictures.
    Good luck with your project, please share your results.

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    Default Re: Thoughts on caulking alternatives

    I am reminded here of the story of the young woman who did not understand the difference between petroleum jelly and seam compound.


    Her boat sank!


    I am sticking with cotton caulking!
    Bird

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    Default Re: Thoughts on caulking alternatives

    5200 only squeezes out of the seam before it cures. Once it cures it is solid and if there is any compression it is minimal. I believe it is as tight as a cotton process and it would be the entire mating surface of 1 1/8" not the less than the 3/8 inch of cotton that I pulled out. As a side note, all of the worm damage that I found was on the inside of the seam where the sealer had failed.

    I am recently retired with time on my hands the boat has been three years in the works so time is not a real issue to me. The concept of doing this as a controlled experience sounds like a great idea. How does one go about doing that? Does anyone have contacts with Sikaflex, Boat life or 3M that I could contact to discuss this?

    My boat would have gone to the wrecking yard had I not gotten it. Some think it should have. I witnessed the wrecking of a 60" Chris Craft that had been pulled to have the bottom glassed. When the estimate of glassing went to $40k they abandoned the boat.

    There will always be the purist that restore boats to original complete with painted canvas decks, 10 coats of varnish and everything original down to screw types. I applaud them, they are true works of art. But I have a beautiful old well built giant. I have upgraded electrical, new aluminum fuel tanks, modern sanitation and plumbing. I use the latest products like Citol instead varnish, Lexon instead of laminated glass, fiberglass on roof decks, TDS on my teak decks, modern navigation equipment and truly great marine paints that last more than a season. So why should I accept that cotton caulking is the only way to make this boat usable today?

    Would anyone want to work with me to document this as a potentially viable solution?
    Last edited by gbroughman; 12-08-2017 at 09:32 AM.

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    Default Re: Thoughts on caulking alternatives

    It seems like you don't understand that the cotton is an important structural part of the system that gives your boat its strength. You could put some high tech modern goop over the cotton instead of traditional seam compound if you want. But I wouldn't omit the cotton.
    Last edited by StevenBauer; 12-08-2017 at 10:30 AM.

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    Default Re: Thoughts on caulking alternatives

    Gerry, to expand on what Steven is saying (and what I, and others, have stated earlier in this thread) - a critical part of the caulking process is that the cotton serves to transfer loads between the planks, reducing shear forces on the fastenings and helping to make the hull a single structure in which forces are distributed throughout. That's what Jay is saying when he notes that the hull begins to ring as the caulking process is completed. That process happens through compression of the cotton using the caulking mallet. There are other techniques that replace the cotton with something else - softwood splines are one option - but whatever is used has to be able to transfer loads between the planks. And while 5200 does dry so that it no longer squeezes out, I don't believe that it has any real strength in compression.

    And to be clear, the advice you are being given has absolutely nothing to do with tradition or some purist ideal. It's an engineering problem not an aesthetic one. You want to replace one engineering solution with a different one. Fine - but when you do that you need to understand what the prior solution was doing and make sure that you are actually solving the same problem.

    Finally, I'll note that I'm an amateur here. My knowledge comes from reading and a certain amount of general engineering knowledge. But you are being given the same advice by some of the most experienced professionals on the forum - boat builders, shipwrights and naval architects. Their recommendations are based on decades of experience and are well worth heeding.
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    Default Re: Thoughts on caulking alternatives

    ^ What Chris said, except that the compression of the cotton makes it strong in shear. It is the ability to transfer shear and resist the forces sliding one plank past the other that stops the hull working and destroying the integrity of the fastenings. Rubbery stuff might resist compression, but will deform under tension or shear.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Thoughts on caulking alternatives

    Cotton (and/or oakum) are driven.
    Seam compound/caulk are not.
    I think that is what the OP is not appreciating.

    DRIVING cotton or oakum into proper carvel seams adds tension, strength and resilience to the entire hull structure, ringing mallet etc. It is both the process and end result that matters.

    Softwoods splines tend to be rung in tightly as well.

    I don't know for a fact the OP will ruin his hull with only compound. He won't be the first to have tried it. Tired planking often means tired seams which can make a proper corking job much more involved. Pretty good chance that Joe Blow at the tech desk of 3M or Sika would be all in for compound only, having no familiarity with more traditional methods.

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    Default Re: Thoughts on caulking alternatives

    Thank you all for the feed back. For the record, I am aware of how cotton and wood swelling has worked for thousands of years. I don't know how "scientific" the process was in the beginning of time or even when my boat was built in Hong Kong in 1973. I am looking for a modern alternative. My views are based on what I have experienced with this boat and specifically the plank replacements (where thru hull fittings failed over time) are put in with no cotton and only 5200 some years ago. I cannot imagine how that would shear where compressed cotton would not. If you do not have any experience with anything other than traditional methods then this thread is not for you.

    I have three years invested in a boat and am not doing this on a whim. It is not about the money as either method is expensive. If this method works than it might be something that would save wood boats in the future where fasteners are less that perfect and old shipwrights are not available to fit with the precision that is required.

    14915206_1323499177668521_3531055250973464459_n.jpg 20161122_172414.jpg20170120_140816.jpg20170120_140753.jpg20170123_162510.jpg

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    Default Re: Thoughts on caulking alternatives

    I can't imagine a 49' long seam filled with 5200 shearing more than about 1/1000th of an inch over it's full length under any conditions, provided that the seam is well and carefully filled for the entire thickness of the planking when the planking is very dry and clean. I would want the seams to be as narrow as possible, like less than 1/8", and I would want the 5200 to squeeze out on the inside. 5200 is bad-assed stuff, and it lasts damned near forever.

    So far as tightening the hull until it rings goes, that's important if all there is in the seams is some fibrous material, but I doubt that it matters much at all with a well bonded semi flexible adhesive.

    I would rather have a slightly compressible material like 5200 in the seams than splines. With tight fitted splines I would worry that the planks would buckle and pull fasteners when they get wet and expand. We've all seen that. We've all seen that with fibrous caulking that's driven in too tightly in narrow seams between very dry planks.

    The fact that traditional systems have worked for a long time is no indication whatsoever that modern systems will not work at least as well.

    You're doing a great job of that, good for you.

    I like the dog.

  33. #33
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    Default Re: Thoughts on caulking alternatives

    Quote Originally Posted by Gib Etheridge View Post

    The fact that traditional systems have worked for a long time is no indication whatsoever that modern systems will not work at least as well.
    Try and insure it for a sea passage.
    It really is quite difficult to build an ugly wooden boat.

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  34. #34
    Join Date
    Jan 2011
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    Default Re: Thoughts on caulking alternatives

    [QUOTE=Eric Hvalsoe;5417904]Cotton (and/or oakum) are driven.
    Seam compound/caulk are not.
    I think that is what the OP is not appreciating.

    DRIVING cotton or oakum into proper carvel seams adds tension, strength and resilience to the entire hull structure, ringing mallet etc. It is both the process and end result that matter.

    This is the real crux of the entire discussion. Smearing some tube goop, no matter how tenacious, into the plank seams will not have the same effect as caulking that is driven into the seam. There are plenty of boats with Sikaflex or some other plastic compound other than linseed putty in the seams on top of traditional caulking, but simply eliminating the caulking and relying on the goop fundamentally alters the structure of a carvel planked hull.
    Im not taking one offshore.....

  35. #35
    Join Date
    Nov 2011
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    Default Re: Thoughts on caulking alternatives

    Could be, but no one will ever know if no one ever does it.

    Not having done it myself, or seen it done, I still think it would be a superior system. People are reluctant to change though, it's the nature of the beast, and insurance companies don't ever take on any more risk than absolutely necessary.

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