Restoring cracked gelcoat on canoe

Discussion in 'Fiberglass and Composite Boat Building' started by canoe42, Jun 13, 2008.

  1. canoe42
    Joined: Sep 2007
    Posts: 14
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    Location: Maine

    canoe42 Junior Member

    I posted here some time ago about refinishing cracked gelcoat on a fiberglass canoe. The consenus was to sand out as much of the cracks as possible and repaint. Now I am into the project and find my 1/4 sheet finish sander with 60grit sandpaper is not up to the task. My guess is I need a disc sander that would be more aggressive. Do not think an orbital sander will do the job and a belt sander is overkill.

    I have done some wood working before and never had good results with a disc sander. They tend to gouge out too much at times and will smooth out raised or beveled areas that are part of the canoes design.

    Any thoughts on what sander to get and some tips on technique would help.

    Thanks,

    Tom
     
  2. the1much
    Joined: Jul 2007
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    Location: maine

    the1much hippie dreams

    a 6" DA should do just fine with 80 grit,,,,and you want a somewhat "gouge",,,the crack needs to be V'd ,,,if you try to sand evenly till the crack is out,,,then you'll end up with a bunch of low spots.
     
  3. Landlubber
    Joined: Jun 2007
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    Location: Brisbane

    Landlubber Senior Member

    A random orbital will do the trick, or a true orbital, but they are dearer.

    Just a 6" one is all you need, electric or air. The best electric is Rupes or Festool, the best air is probably Dynabrade.

    I know it is only a canoe, the tools will last a lifetime anyhow.
     
  4. canoe42
    Joined: Sep 2007
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    Location: Maine

    canoe42 Junior Member

    Photos of canoe with cracked gelcoat

    As you can see there is not just one crack in the gelcoat. The cracks are throughout the entire coating. Do not expect to get a smooth glossy finish out of it, just something that looks a little better. The canoe was given to me and does not leak, even where there is the big ding (see photo). I figure for a weeks worth of sanding and painting I have a half way decent canoe.

    I know how to repair the big ding with fiberglass. All the cracks have raised edges. Previous replys said a good sanding will reduce the raised edges but not eliminate the cracks. One photo shows the cracks sanded and the other is not sanded. On the sanded one you can see a light blue line on either side of the cracks showing where the raised edges have been sanded down. I could then finish in 2 ways: apply new clear gelcoat and paint, or just prime and paint with either automotive or a good quality house paint. If anyone has another way of refinishing this canoe please jump in.

    My concern now is how to sand down the cracks more effectively. Looks like a 6" disc sander is the way to go. Just a little concerned about sanding down raised edges on the canoe that are part of the canoes desogn. Tipa of technique would help.

    Thanks

    [​IMG]

    [​IMG]

    [​IMG]
     
  5. Landlubber
    Joined: Jun 2007
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    Location: Brisbane

    Landlubber Senior Member

    Sorry canoe,

    You have missed one "small" thing when we say orbital, they are NOT disc sanders. Disc sanders rotate at the speed of the drive motor. Random or dual action sanders are disc, yes, but they rotate at a different speed to the drive motor. The random is in fact capable of zero rotational speed if you hold the disc, the dual action sander is gear driven, it rotates and spins as well.

    Having looked at the poor pics, may I suggest that you forget trying to sand out these cracks, the gelcoat is buggered, as is actually the laminate, but seeing as it is only a canoe, the structural strength is probably still enough to hold it together.

    If you insist on repairing the thing, get rid of all the gelcoat, and respray another layer over the boat, using this time an epoxy spraying putty, sand fair then paint as per any other job.
     
  6. the1much
    Joined: Jul 2007
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    Location: maine

    the1much hippie dreams

    what he says,,hehe,,,sorry man,,,no help with that gel job,,,if ya see glass in ya crack,,hehe that sounded funny in my head,,but since your crack goes all the way to your glass,,and the delamination IS all the way around ya canoe,,trust me,,,the ONLY way of fixing it is like landy said,,,take ALL the old off and spray new,,,if all ya wanted to do was get rid of the cracks,,and not repaint,,then the poor thing would only last a few more months,,,if that,,,,once water gets into ya glass you'll be sinking soon,,sorry man.
     
  7. fiberglass jack
    Joined: Dec 2005
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    Location: toronto

    fiberglass jack Senior Member

    the amount of work involved it be better to pick up a new one, the cost alone for the resin glass and paint will be close to a new one
     
    1 person likes this.

  8. Landlubber
    Joined: Jun 2007
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    Location: Brisbane

    Landlubber Senior Member

    Can only agee jack, put it out of its misery, .45 will fix it. Right between the eyes.
     
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