Patching a gouge/crack...

Discussion in 'Boat Yard Basics' started by DavidIvey, Jan 16, 2012.

  1. The gouge/crack below was patched many years ago with some cheap crap, but I have some left over Raka Epoxy that I plan to fix it with this time.

    My question is what is the best way to fix it? I've never really done a patch before so Im not sure of the best way to do it or what Oz. cloth/mat to use. There are other bad places under the boat and this is going to be my "test" run.

    As you can see I've sanded it down with some 60 grit so far.. Any tips/help is GREATLY appreciated!

    [​IMG]
     
  2. paint it black

    paint it black Paddling away...

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    I'm not too familiar with Epoxy. But I suggest you grind the gelcoat back. You're going to want to lay glass on glass. Not glass on gelcoat.

    You're not supposed to use mat with epoxy resin. The substance used to hold the chop strands together to create mat don't mix with epoxy. It'll just gum up. Go with either a cloth, or a biax.
    The chop strand on biax is actually stitched to the cloth, rather than held together by said substance. I personally use 1708 when doing anything...lol
     

  3. I've got some 1700 from when I did my transom but I just can't see me using that. That seems a little much for such a small area, but Im no expert either.

    So I've got to remove the gel coat all together? Basically all the way down to the actual fiberglass? If so Im gonna need more than 60 grit....
     
  4. DuckNut

    DuckNut Brandon, FL

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    Sand it all down and the gel coat a little (ie: 1") past the damaged area. Cut the cloth to cover the gouge and another to cover the extra sanding. Wet the area apply the cloth; small piece first. This will take so very little epoxy but you need to mix more than you will need or you may not get it to set up.

    After cured, mix in some filler material and do the final patch. Sand and paint.

    You dont need that heavy of cloth 6 or 9oz would be plenty.

    Give me your address and I'll mail you some. Tell me how long and wide you need then I will double it.
     

  5. DuckNut you are too kind! Im guessing that my Raka Epoxy will be ok to use with your cloth?

    As you can see I sanded past the gouge and hair line cracks. From what I read I also need to open those small stress cracks up some so that the epoxy can get inside better.

    After sanding I will layup the cloth which is sized the same as the gouge then layup the larger piece over top of it. Once cured I can mix my filler and fill in any low lying areas so that it all will sand smooth...

    How is that?

    DuckNut, I'm going to get a mesurement and PM you my Address.. No Anthrax please..  :D :D

    EDIT:

    Just went to grab the measurement and I noticed that around the cracks and gouge the color was darker, but as you can see around that area is lighter in color. Im guess this is where water seaped in and is now coming back out?

    [​IMG]
     
  6. Brett

    Brett > PRO STAFF <

    Tilt/block the hull so that the crack is the lowest point.
    Let it sit, watch to see if a drip develops.
    Laminating epoxy won't bond to a water wet surface.
     
  7. What should I do about my gel coat? Can I just paint over the patch instead of gel coating?

    I have a lot more areas to repatch and I'm not sure what to do about the gelcoat for such a large area either. I won't be starting that project for a few months, so my main concern is gelcoating or painting my current patch.

    Like I said this patch is going to be my learning curve for when I go to take the rest of the boat.
     
  8. Brett

    Brett > PRO STAFF <

    Gelcoat is a finish coat intended to protect polyester resin from soaking up water.
    You can use it over epoxy, but I've found that Krylon in a rattle can works fine.
    Just have to match the hull color to the cap color on the spray can. I'm not much
    for yacht finish on a hull that's going to be scraping against oysters or barnacles.

    ;)
     
  9. I just want something that will help protect it against abrasions. Since I still have my mud motor I have the ability to run in 1" of water or less, I rarely do but I can if needed. With that being said I've noticed that there is a fair amount of shell in some areas that would scrap up the bottom of the boat so I was wanting something that would be fairly tough. If a good coat of spray paint is what most are doing then I have no objections.

    I dont mind spending a little extra for better protection.
     
  10. Brett

    Brett > PRO STAFF <

    For abrasion coating I'd use a mix of epoxy, graphite powder and cab-o-sil.

    From my research when working on the Slipper...

    MAS Epoxies
    West Systems
    Ted Moores, 1997 edition of Canoecraft
     
  11. Sounds like mixing all of those together would be a science project lol. Here is a dumb question: I wouldn't need paint for the mixture below, right?

    Thanks for the information, I'm gonna go read about them.


     
  12. Brett

    Brett > PRO STAFF <

    No paint applied over the abrasion coat, only on the topsides

    From another thread...

     
  13. That looks good! My boat is mostly green/Camo colors so this would be perfect.

    From what I gather in the above post is that the graphite and epoxy mix will be my last coat and will be the epoxy/graphite only, no cloth.
     
  14. Here is a link I found on google.. There is some good talk towards the bottom of the page about graphite and how it makes the epoxy less rigid once cured if anyone cares to read. Other good stuff too, but it's a wood boat forum..

    http://forum.woodenboat.com/showthread.php?77424-Should-I-graphite-my-hull
     
  15. Well that was water coming out of the cracks.. Upon closer inspection I noticed that I could removed more of the gelcoat and a wee bit of fiberglass. So the gouge turned in to a scrape. I also had to remove the wet foam on the other side and this is a pain. Im still not done removing all the foam, but I have removed it from behind the scrape. Also the old glass is fairly flimsy in this area.

    I plan to remove all the foam, clean and sand the area and laydown two layers of 1700 biax behind the scrape. On the outside of the hull I will glass and fill in the scrape. As for the small stress cracks I have gouged them will a small cutting wheel on my Dremel to enable the filler to actually get into the crack.

    Anyone have any suggestions? Or is this ok?

    This sucks..now I cant fish tomorrow!!!!!!
     
  16. Brett

    Brett > PRO STAFF <

    SD, don't over think this....it's a fiberglass boat, with a little time and effort you'll get it done.
    If you don't like how the repair looks, after the first time, you'll know how to do it better.
    You will learn more from mistakes than getting it right the first time. It's how I learned.
    Just remember rule #1: If you're getting dirty, you're doing it wrong.
     
  17. DuckNut

    DuckNut Brandon, FL

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    Graphite is used for reducing frition such as for sliding over vegiatation.

    Aluminum powder is for abrasion resistance. It is product 420 on West System.
     
  18. Yeah, Im not too worried about how it looks, just as long as it's functional! ;D

    There wasn't really another choice besides removing the wet foam. So I had to cut into it. I got the foam out from over the scrape and cleaned it up as much as I could. To be honest this boat needs to be taking down to just the hull and redone. It's lacking flotation... :-[

    I was actually talking to some one back home about the boat and they don't understand why I just don't buy a used Gheenoe. :-/