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  1. #1

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    repairing crack in GPR hull?

    Had a little run in with a sunken barge yesterday. Didn't notice at the time, but put a small crack in the hull. About 6" long, right at the keel. Ski didn't sink or anything, but I noticed a small puddle of water on the garage floor this morning where it leaked out of the crack, that's when I noticed the crack. It's small, less than 6" long, and looks like a stress crack would in fiberglass. The point of impact with the metal rod protruding from the deck of the barge is off to the edge of the crack a bit, so the crack is from the hull flexing at this point. When I hit the barge I was slowly coasting, power off. I was trying to drift right over it, which would have worked had there not been big pieces of steel protruding from what's left of the wooden deck (barge sunk probably in the 30's).

    Any pointers on fixing it? It's right at the bow, so access from inside is nil. It's small enough that i'd like to avoid an insurance claim, and i'd also like to avoid tearing out the interior of the hull in the front. Plus it's October - any delay and the season is gone, as it stands i'll probably only get a couple more good rides (with the wetsuit, of course) before I'm done for the season.

    I was thinking of drilling small holes at each end of the crack (to prevent it from spreading), then grinding it out with a small bit on an air grinder and filling it with marine-tex.


  2. #2

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    lets see some pics...for cracks and major stuff i use westsystems but marine tex is good for little things. I think some people use it on this type of repair but so far i only use it for filling minor to medium gouges and nicks. Nothing thats a real crack so far. Maybe someone else can chime in for you... Either way if your looking for a factory or even close finish the cheapest way would probably be a comprehensive claim... best of luck and lets see pics!

  3. #3
    YoYamma's Avatar
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    Dave that sucks, hope ya get it sorted out.
    Also hope you report that hazard to the authorities so they can put a proper marker on it for other boaters.

  4. #4
    speedskixp's Avatar
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    West systems epoxy. You need to drill a small hole at each end of the crack to stop it from spreading. Then take a small grinder or dremel and V the crack and rough up the area around it so the epoxy will stick. Then you need to mix up some resin and shred up some glass matte and fill the area, Then take a piece of masking tape and use it to cover the wet glass and smooth it out. Remove the tape when the resin is dry. Shape the area and lay a layer of wetted matte over it. OR another option would be to go to an autobody supply store and pick up some 3M panel bonder instead of the west system. Follow all the same steps except you will fill the area with the panel bonder. It's Very strong stuff and not too hard to sand. Once dry you want to sand it smooth starting with a quick sand with 80 grit then moving to 180 and 320 for primer. If you are not worried about looks right now you can just sand smooth and leave it for winter to finish it. Hope this helps. Btw obviously it is always best to repair from both sides but if that is not an option and the damage is small I think you will be ok. Whatever you do make sure you do not use polyester resin as it will not stick to the smc plastic.

    Here is what happend to my rxp hull when I hit a submerged dock at about 40mph. post 4
    http://www.greenhulk.net/forums/show...int&highlight=
    Last edited by speedskixp; 10-04-2010 at 09:30 AM.

  5. #5

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    Quote Originally Posted by YoYamma View Post
    Dave that sucks, hope ya get it sorted out.
    Also hope you report that hazard to the authorities so they can put a proper marker on it for other boaters.
    Oh, I knew it was there. Just thought I had a couple more inches of water, and didn't realize there were metal rods sticking up. It's just outside the channel, just one of those cool things to check out, and we were exploring.

    I can do the west system, just a little more $$ and time. I'm not worried about cosmetic at all really. It'll be flat black when I'm done anyway.

    I looked more closely and found a few more smaller cracks in the area. So I think I'll fill with west systems then add a thin patch (1 layer of cloth) over all of it. I'll have to look around my garage, I should still have some resin from my tunnel reinforcement.

  6. #6
    1200Jet's Avatar
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    This crack will need a proper repair you can't just fill it and forget it. Stop drilling fiberglass is pointless, it needs to be scarped out around 2 inches either side of the crack and 2 inches past the ends of the crack. Then it needs to be repaired with epoxy and woven mat, chopstrand is not compatible with epoxy. Do some research on the west systems website they have plenty of instructions for all boat repairs. Good luck

  7. #7
    Duke's Avatar
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    Quote Originally Posted by speedskixp View Post
    West systems epoxy. You need to drill a small hole at each end of the crack to stop it from spreading. Then take a small grinder or dremel and V the crack and rough up the area around it so the epoxy will stick. Then you need to mix up some resin and shred up some glass matte and fill the area, Then take a piece of masking tape and use it to cover the wet glass and smooth it out. Remove the tape when the resin is dry. OR another option would be to go to an autobody supply store and pick up some 3M panel bonder instead of the west system. Follow all the same steps except you will fill the area with the panel bonder. It's Very strong stuff and not too hard to sand. Once dry you want to sand it smooth starting with a quick sand with 80 grit then moving to 180 and 320 for primer. If you are not worried about looks right now you can just sand smooth and leave it for winter to finish it. Hope this helps. Btw obviously it is always best to repair from both sides but if that is not an option and the damage is small I think you will be ok. Whatever you do make sure you do not use polyester resin as it will not stick to the smc plastic.

    Here is what happend to my rxp hull when I hit a submerged dock at about 40mph. post 4
    http://www.greenhulk.net/forums/show...int&highlight=
    Quote Originally Posted by 1200Jet View Post
    This crack will need a proper repair you can't just fill it and forget it. Stop drilling fiberglass is pointless, it needs to be scarped out around 2 inches either side of the crack and 2 inches past the ends of the crack. Then it needs to be repaired with epoxy and woven mat, chopstrand is not compatible with epoxy. Do some research on the west systems website they have plenty of instructions for all boat repairs. Good luck
    +1

    Its SMC not fiberglass so epoxy resin must be used instead of regular. West Sytems is very good.

  8. #8

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    I think I'm just going to use marine-tex. No way I'm going to be able to get a good repair with west systems, I can't get to the inside of it to patch it properly and I can't realistically flip the boat to fix it. If I try to use resin / fiberglass it'll all just flow out of the repair area and i'll be screwed.

    I've got it sanded down and i've ground down the cracks. most don't seem to penetrate through the hull, it seems that there is quite a bit of filler or fairing compound in this area to get the proper hull shape. It looks like it's been repaired before. I've ground the crack out about 1/2" deep and 1/2" wide and I'm going to just fill it with marine tex. 90% of the crack is gone, i'm going to grind a little further in the area where there still appears to be cracking, clean it up good, and fill it out with marine tex. I'll keep an eye on it the next few times out and if it comes back i'll call the insurance company. If it fails again, it'll just fill the void between the hull and the liner, i'll drain it when I get back to shore, and buy a hull or have the insurance fix this one.

    I've already stop drilled all the cracks. Most disappeared when I ground them, they weren't all the way through, so I just have to fill the drilled holes and the ground area.

    Off to west marine to return the west systems and get more marine-tex...

  9. #9
    1200Jet's Avatar
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    You wont have any issues with the epoxy flowing away from the repair, you only need enough to wet out the cloth.

    If you have ground the crack 1/2 inch deep you will be through the hull? I would really stress you dont do a bandaid reair on this?

  10. #10

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    Not through the hull. At least a 1/2" deep. Looks like the keel may have been ripped out of this thing at one point. The bulge on the bow is all filler. Lot's of filler down the keel too.

    Marine-tex is like 4k psi tensile strength. Should be plenty strong enough to repair a crack. This is not delamination, not a puncture, just a crack. 2-3 cracks actually, but still just cracks. Only one of which appears to actually penetrate the hull.

    When I'm done forming it out with the marine-tex, I may do a layer of cloth over it for good measure. I'll probably use marine-tex as the resin there, but I do have some west systems 105 and 206 hardener if I want to go that route. The 105 will wet the cloth better but I think the marine-tex will stick to the marine-tex better.

    I don't know how I'm going to get a good repair by jamming wetted cloth in the crack, or resin with chopped strand. That sounds like a much worse band-aid than grinding it out and filling it in with marine-tex.

    Marine-tex is an epoxy resin that can be used with fiberglass cloth as reinforcement. It does stick to SMC and based on the specs is much better suited to filling in a crack like this than resin or resin with chopped strand mixed in. It is also of a consistency that is easier to work with than resin, when working overhead.

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