Urethane glue as a wet crack plug.

Discussion in 'Fiberglass and Composite Boat Building' started by markstrimaran, Apr 29, 2018.

  1. markstrimaran
    Joined: Dec 2014
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    markstrimaran Senior Member

    20180429_172034.jpg
    The crack is from ice, originally, A roller on the trailer, stressed the old repair.

    The boat is foam sandwiched, no access in bilge.

    Non structural.

    Thinking maybe gorilla glue in a syringe, after drilling some 1/8 holes along it for access

    It might never actually dry, unless I cut it open, maybe later.

    Any other options, epoxies,

    Their is about a 2" air gap between the foam and the crack.
    20150310_125443.jpg
    Old build photo 4 years ago.
    The white tube is PVC bilge drain, above crack. 20150310_155640.jpg maybe drill one hole and inject a hole can of 2 pound foam
     
  2. Yellowjacket
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    Yellowjacket Senior Member

    Fix it properly... Injecting glue or foam is like putting a Band-Aid on stab wound... Cut out the damaged material and feather it out over a reasonable amount and if you want foam behind it, then add a rigid foam (and most foams from a can aren't rigid), then shape it and put on glass and epoxy to fix it right. If you don't you're going to be coming back later and doing it again... Also letting water wick into the damaged glass will result in bubbling later.. It doesn't take that long to fix it properly, just do it right.
     
    rwatson likes this.
  3. markstrimaran
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    markstrimaran Senior Member

    It's the moisture seeping from it, that is causing me to try urethane.

    If I could get it dry out, it's just warm enough to cure resins, as spring has set in..
    I know I need a long term patch. That would require turning the boat upside down. Just trying to find a quick temporary 6 month patch,
     
    Last edited: Apr 30, 2018
  4. gonzo
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    gonzo Senior Member

    There is no need to turn the boat upside down. Repairs on bottoms are routinely done with the boat on a trailer or in blocks.
     
  5. markstrimaran
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    markstrimaran Senior Member

    Well, gravity is going to seep water into the repair as it cures.

    Which is why I think urethane foaming glue might do the trick. As it needs moisture to cure.
     
  6. gonzo
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    gonzo Senior Member

    You need to dry it first. The area need to be ground and the crack opened before any repair is done. If water is seeping out, urethane foam will pour out together with the water. Also, it won't adhere to whatever is behind the crack.
     
  7. PAR
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    PAR Yacht Designer/Builder

    You're over thinking this Mark. Urethane foaming glue isn't waterproof in the foaming areas that ooze out from a non-compressed joint. In fact, for these types of glues to work (foaming polyurethanes) require a well fitted joint (tight), or they don't bond very well and are not waterproof in this state.

    The image shows a portion of delamination, a crack, possibly part of the delamination of maybe just a deep scratch or gouge. This is an easy repair and it involves opening up the area, for two reasons. The first is so it doesn't take months to dry out, just a few days in warm weather and second; so the bad laminate can be ground away and new, waterproof laminate applied. Afterward a cosmetic finish coat is applied and you can repaint or apply gelcoat.

    Yes, it would be nice to just apply some magic goo in a tube and solve the problem, but most of these products don't work well in this type of situation. If you go ahead and use your suggested approuch, the moisture that does drip into the urethane will not be just moisture. It'll be dirty moisture, quite dirty in fact, likely mixed with styrene and other chemicals, because it's been there a while and likely started some osmosis. So, the foaming cure all will cure with all sorts of chemicals, probably not very well suited to its proper curing. On the other hand, give it a try, you might get lucky and you've saved the day. I'd bet it'll just open up again, in short order and you'll be back here asking how to clean out the urethane, before you make a proper repair. If you must use a magic goo in a tube, I'd recommend 3M-5200, which is waterproof once fully cured.
     
  8. markstrimaran
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    markstrimaran Senior Member

    20180430_181749.jpg
    It did not drip any when I opened it up 1/8". Its centered on the peak of the keel.

    Three days of rain coming. So hopefully the top side is water proof.
     
  9. PAR
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    PAR Yacht Designer/Builder

    Since you've bit the bullet, grind the surrounding area, feathering it back with a generous taper (12:1). This will provide a place for the new fabric to live and not stand proud of the surface. It also provides a good bonding grip from the old hull shell to the new repair. I'd just use a big angle grinder with a very coarse grit and plow a concave area all around the area.
     

  10. markstrimaran
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    markstrimaran Senior Member

    20180502_172704.jpg
    Thanks for the inspiration, to fix it right. I used PC 3, Epoxy cement to dam the seepage the day before gassing it.

    Now for the dagger board cassette that blew out last fall.
     
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