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Thread: Wood movement

  1. #1

    Wood movement

    I have what is probably an out-of-the-box question. I am a woodworker but not a boat builder. For years I have thought about building what would actually be a sculptural piece for over the couch in my living room. Think of a large sculpted half hull. I'm thinking it would be 5 to 6 feet in length. For both economy of wood and weight I would like to use thin strips and attached them to ribs/panels. My concern is that the grain direction of the strips to the ribs/panels will be at right angles. If I use non-grain material such as particleboard, plywood, plastic, etc. how will I allow for movement (expansion and contraction across the grain) of the strips. Will they not buckle or warp. I live in Michigan where there are extreme differences in humidity between winter and summer. I plan on using cherry. I hope this explanation is clear. Thanks in advance for any help or suggestions you can offer.

  2. #2
    Join Date
    Dec 2016
    Location
    South West Ontario
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    866
    If the strips are just secured with just one stylish rivet in the middle of the board at the ribs it will let it move across the grain. The strips would need tapered overlap on the edges to allow for movement. Clearly this is cosmetic not water tight!
    ​You can do a lot with very little! You can do a little more with a lot!

  3. #3
    I built the hull for a 1:35 model J class. From bow to stern is about 42" long. The kit came with "frames" made from plywood. To that I glued thin strips running bow to stern. Over that I glued thinner strips at about a 45 degree angle. The hull was completed about 2 years and and so far there has been no problem with wood movement. We have the house open all winter and under AC all summer and it gets very dry inside.

    I filled the space between the frames with balsa to make it easier to tack glue the first planking.


    For the second layer I used light mahogany veneer I cut into strips. I didn't like the wood the kit supplied.




    FWIW, I used hot hide glue for the second planking. It bonds quickly, cleans up easily and doesn't leave any reside behind to ruin the finish.
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  4. #4
    Join Date
    Apr 2015
    Location
    Bay of Plenty, New Zealand
    Posts
    45
    The contraction / expansion is a problem when timber runs in a straight line but because the hull and ribs are all curved it is not a problem. In lapstrake boatbuilding the edges of the boards get riveted together but still the wood needs to swell up if the boats has been out of the water for some time and the wood has dried up (and shrunk). When using plywood for the hull the lapstrakes would just be glued together with resorcinol glue, if it would be only temporary in the water and well finished (eg a canoe) we would use UF glue (plastic resin). Be wary with UF of the expiry date, depending on the temperature it is being stored at it might go off in as little as 6 months. The changing laws in e.g. Calfornia has macufacturers of glue fiddling around with it and the only one I have found acceptable is Pro glue veneer bond dry resin. PTreeUSA.com has it. I have a dislike for expoxy after some bad experiences and you can find postings on the web about literally a boat is falling apart because of the expoxy glue failing. Ofcourse you can use hide glue as well.

  5. #5
    Quote Originally Posted by Marinus Loewensteijn View Post
    The contraction / expansion is a problem when timber runs in a straight line but because the hull and ribs are all curved it is not a problem. In lapstrake boatbuilding the edges of the boards get riveted together but still the wood needs to swell up if the boats has been out of the water for some time and the wood has dried up (and shrunk). When using plywood for the hull the lapstrakes would just be glued together with resorcinol glue, if it would be only temporary in the water and well finished (eg a canoe) we would use UF glue (plastic resin). Be wary with UF of the expiry date, depending on the temperature it is being stored at it might go off in as little as 6 months. The changing laws in e.g. Calfornia has macufacturers of glue fiddling around with it and the only one I have found acceptable is Pro glue veneer bond dry resin. PTreeUSA.com has it. I have a dislike for expoxy after some bad experiences and you can find postings on the web about literally a boat is falling apart because of the expoxy glue failing. Ofcourse you can use hide glue as well.
    Urea-formaldehyde "plastic resin" adhesives are fine when properly used. On the other hand, epoxy resin adhesives are also fine when properly used (unless one suffers from an allergy to the hardener). Boats falling apart and epoxy "glue" failing are symptoms of improperly used epoxy. Many fine epoxy laminated boats are sailing after 40 years, still in fine condition. A few failures can highlight the seriousness of learning to follow directions, particularly when building something that people's lives may depend on proper work. Improperly used urea formaldehyde adhesives can be misused and fail too. They are as much dependent on proper work as any other adhesive.

    I have been using epoxy resins for boat building and repairs for 30 or so years and I have never had a failure of an adhesive bond or lamination. Good guidance is available on the West Systems web site, with a very substantial amount of information. See https://www.westsystem.com/instruction-2/
    Fair winds and following seas,
    Jim Waldron

  6. #6
    Join Date
    Apr 2015
    Location
    Bay of Plenty, New Zealand
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    45
    Quote Originally Posted by James Waldron View Post
    Urea-formaldehyde "plastic resin" adhesives are fine when properly used. On the other hand, epoxy resin adhesives are also fine when properly used (unless one suffers from an allergy to the hardener). Boats falling apart and epoxy "glue" failing are symptoms of improperly used epoxy. Many fine epoxy laminated boats are sailing after 40 years, still in fine condition. A few failures can highlight the seriousness of learning to follow directions, particularly when building something that people's lives may depend on proper work. Improperly used urea formaldehyde adhesives can be misused and fail too. They are as much dependent on proper work as any other adhesive.

    I have been using epoxy resins for boat building and repairs for 30 or so years and I have never had a failure of an adhesive bond or lamination. Good guidance is available on the West Systems web site, with a very substantial amount of information. See https://www.westsystem.com/instruction-2/
    I'm familiar with the West system, having used it myself when it first was introduced. With expoxy failing the argument always was that it was improperly used where the user stated that (s)he used it properly and followed the instructions. Fortunately I'm out of the boat building endavours so no longer worry about it.

  7. #7
    Quote Originally Posted by Marinus Loewensteijn View Post
    I'm familiar with the West system, having used it myself when it first was introduced. With expoxy failing the argument always was that it was improperly used where the user stated that (s)he used it properly and followed the instructions. Fortunately I'm out of the boat building endavours so no longer worry about it.
    Well, if you saw it on the Internet, it must be true!

    But then again, if West Systems got sued and put out of business because of all their product failures, it hasn't made it yet into the news or onto the Internet.

    Edit: And if epoxy resins were so failure prone, why would so many New Zealand boat builders be using it in commercial production? Lots of cold molded hulls are floating all around the world laminated with epoxy resins.
    Last edited by James Waldron; 09-09-2019 at 2:12 PM. Reason: Afterthought
    Fair winds and following seas,
    Jim Waldron

  8. #8
    Join Date
    Apr 2017
    Location
    Michigan
    Posts
    746
    Julie
    You are amazing. Is there anything you haven't tried?

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