Dynel sheathing?

Discussion in 'Wooden Boat Building and Restoration' started by SeaWitch1939, Oct 29, 2014.

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  1. SeaWitch1939

    SeaWitch1939 Previous Member

    I have a few things to do now in prep for her trip up the ICW in the spring.


    My question is about Dynel (EDIT THXS) sheathing.

    How hard will it be to sand off from the hull?

    I believe she has a thin layer above the waterline, and a thicker layer below.
    How good is Dynex in keeping water out of the hull, assuming it was not breached with a hole etc? As she sits right now, she is dry, floats good. How strong is this stuff? Seeing how the bilges are dry, even if the wood has rot starting, how much extra structural strength will it offer.

    My short term goal is to haul her, clean/paint bottom & inspect for anything major, then power her up the ICW in the spring, put her on the hard at my place, for a total classic style refit.

    Thanks

    Seawitch
    [​IMG]
     
  2. Tad
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    Tad Boat Designer

    Assume you mean Dynel?

    If you google Dynel there's lots of opinions out there.
     
  3. PAR
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    PAR Yacht Designer/Builder

    Dynel is about 3 times better at abrasion resistance, compared to similar weight 'glass cloth. It's adds no strength to the substrate and does greatly improve waterproofing qualities if applied properly. It's not as easy to apply as 'glass fabrics, mostly because it tends to float in the goo, but (again) if applied properly, it's significantly better than regular 'glass cloth.

    Sanding it off will be a *****. It's a resin rich product, so you'll be sanding lots of resin. If the sheathing is in good shape, just make repairs to dings and digs and repaint. If the sheathing needs to come off, bring lots of beer, so you can ease the pain of removing it.
     
  4. sdowney717
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    sdowney717 Senior Member

    hmm, got to wonder why it was dyneled by a prior owner?
    Significant issues perhaps enough that they did that.

    You think you can accomplish this refit.
    How many project boats never get finished.

    So are you doing this yourself or paying a whole lot of people a lot of money?

    "even if the wood has rot starting"

    Does it have wood rot? If it does not, then why do this?
     
  5. SeaWitch1939

    SeaWitch1939 Previous Member

    Glass Half full for now.....All speculation until i get her out and take a peek.
    I will be doing the refit myself. I doubt they did the Dynel for a patch job.
    It was done before a 2012 survey, and it checked out then. The survey would have shown any major issues with the structure.
    I have a feeling she is okay, but expect the worse, a complete tear down and rebuild over a couple years.
    We shall see
     
  6. bpw
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    bpw Senior Member

    You have an awful lot of confidence in a person who was working for the buyer two years ago. Get your own survey before you start spending money, it will be worth it.

    The dynel is a bad sign. I hope you really like the boat and have a big pile of money.
     
  7. PAR
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    PAR Yacht Designer/Builder

    There's nothing intrinsically wrong with a Dynel sheathing. I would have used Xynole, but Dynel is popular in some places and is more available, as well. My concerns are what was the condition of the planking and it's fasteners, when the Dynel sheathing was applied. If the hull was sound, the Dynel should be fine, but if the hull was working, they'll likely be issues with the sheathing. Dynel as toughness to a substrate, but not much modulus, so . . .
     
  8. sdowney717
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    sdowney717 Senior Member

    If nothing wrong with the wood structure, then the Dynel is a plus, helps keep the boat afloat.

    If you are concerned with stopping rot, then mix boric acid in hot water and spray regularly. Or boric acid mix with ethylene glycol antifreeze. Kills rot dead.
    And kills bugs.
     
  9. CDBarry
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    CDBarry Senior Member

    Note that rot usually requires fresh water and thus starts from the inside, from rain or condensation. The sheathing may not be the issue.
     
  10. sdowney717
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    sdowney717 Senior Member

    Dynel also prevent worms, gribbles from eating, boring the hull.
     
  11. bpw
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    bpw Senior Member

    I should have said a well done Dynel sheath applied to a vessel in good condition can be just fine, but when Dynel has been recently applied to a 70+ year old boat it is almost always bad news. People rarely bother to Dynel an old boat that doesn't have issues.

    Gotten a survey yet? hard to make a plan until you know the actual condition of the boat.
     
  12. Steve W
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    Steve W Senior Member

    A good thoughtful analysis. It is also not generally a good plan to sheath an old carvel planked boat with anything unless its sufficient to overcome the hull movement such as cold molding, a heavy glass laminate, or a ferro cement sheath. Dynel is a great product and i have used lots of it but only on plywood or cold molded boats.

    Steve.
     
  13. Easy Rider
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    Easy Rider Senior Member

    I covered a propeller for an ultralight aircraft for abrasion resistance and it was so abrasion resistant I could not sand it. Had to throw the prop away.
     
  14. gonzo
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    gonzo Senior Member

    I am sure I saw that boat at Cracker Boy Marina years ago. It was a patchwork of repairs and showed fastener sickness. The owner at the time offered to sell her for owed storage fees. Have a surveyor or boat carpenter check her out.
     

  15. Milehog
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    Milehog Clever Quip

    I believe that is still the asking price & suspect the marina is the owner now.
    <removed>
     
    Last edited by a moderator: Nov 12, 2014
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