Coosa - Thermoweld?

Discussion in 'Fiberglass and Composite Boat Building' started by SaltOntheBrain, Jul 7, 2015.

  1. SaltOntheBrain
    Joined: Feb 2007
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    SaltOntheBrain Senior Member

    I've done some searches and not a single hit.
    Anybody know if Coosa board can be thermowelded like other PE board?
    The PE tanks on our firetrucks are plenty durable even without the fiberglass in the Coosa.
    Every thread I've read involving Coosa has turned ugly. People who haven't so much as seen the product claiming it's heavy, soft, unsuited for anything.
    Others claiming that nothing will stick to it...not paint, polyester, vinylester, epoxy...nothing.
    Who is building what with it besides transom cores? Is epoxy screw-n-glue adequate? Will screws and/or thermoweld be as good? Better?
    It would be nice to hear from someone with actual knowledge, not just a keyboard and an opinion.
    LF
     
  2. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    It isn't PE though, it is PU.
     
  3. SaltOntheBrain
    Joined: Feb 2007
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    SaltOntheBrain Senior Member

    Oops, yeah, that.
    Same questions, though.
    LF
     
  4. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    I think the biggest complaint is the cost, that's the main reason it's not used more than it is.
     
  5. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Can't be welded so far as I know, but a lot of what you said about PE is probably true. You seem to be confusing Coosa board, which is a re-inforced high density polyurethane foam, with Polyethylene, which is a solid thermoplastic. What are you wanting to make ?
     
  6. SaltOntheBrain
    Joined: Feb 2007
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    SaltOntheBrain Senior Member

    Yeah, I talked to Coosa. No thermoweld.
    There's been a lot of misinformation and outright BS about this product on this board and a couple of others. Threads deteriorated into shouting matches where someone claimed that anyone who used it as a core was a hack because nothing would bond to it and it would eventually delaminate.
    Mostly, I want to use it for stringers and deck, (screw and glue) but I'm also considering using it for the hull of a flat bottomed skiff. I know it costs more, but it can also simplify things quite a bit by only having one type of material for the entire skiff.
    No need to glass, just screw, glue, and paint.
    I've also heard of someone thermoforming it, but I haven't talked to them yet, so I'm not certain if it's true. If it is, then it should be easy to use it like steamed wood around cockpit coamings, etc.
    My background is aluminum boats, but a completely flat bottomed aluminum skiff will either be too complicated or too heavy for what I want, and it will be noisy. I plan to beat the crap out of the boat. Gravel, river rocks, oysters, etc., and I don't plan on inspecting for damage every time I graze the bottom. Cost will be comparable to aluminum, even if it's considerably more expensive than plywood.
    LF
     
  7. Steve W
    Joined: Jul 2004
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    Location: Duluth, Minnesota

    Steve W Senior Member

    I use coosa quite a bit, its a good product as it does not absorb water. When it first came on the market I ordered some samples and did my own testing for water absorbtion by weighing pieces on a gram scale and then submerging it for a month and re weighing with no significant uptake. So I now use it as a core replacement where the weight is not a concern. No it is not thermoweldable as it is a PU foam. I think it would be used more if it were more readily available and if it were available in a scrimmed contour form like all the other cores. When I use it in a deck for example I have to strip plank with it when using it in cambered decks. The price is not too much of an issue as you are not generally using a lot of it. I recently used some recoring a hardware intensive section of deck on a Hans Christian 38 where it was replacing de laminated, wet 3/4" hardwood plywood core so weight was not an issue. It makes a good core replacement under hardware in lower density foam or balsa decks.

    Steve.
     
  8. SaltOntheBrain
    Joined: Feb 2007
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    SaltOntheBrain Senior Member

    Coosa told me yesterday that one of their customers is crowning it to use as cabin roofs, crowned decks, etc., but they thought he was laminating 2 thinner sheets to get his curves. It was a secret, I guess.
    A company called Eden Coast it making high end garage doors and gates out of it. It seems like most places that use it are making big bucks from it and are reluctant to share their knowledge.
    Steve, what is scrimmed contour?
    LF
     

  9. SaltOntheBrain
    Joined: Feb 2007
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    SaltOntheBrain Senior Member

    Got it. Scrimmed is cloth on one side and scored to allow bending.
     
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