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B.S.
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Discussion Starter · #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!

 

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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
 

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B.S.
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Discussion Starter · #3 ·
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
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....
 

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B.S.
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Discussion Starter · #4 ·
Any one else?
 

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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.
 

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B.S.
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Discussion Starter · #6 ·
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.

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?

 

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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.
 

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B.S.
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Discussion Starter · #8 ·
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.
 

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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.

;)
 

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B.S.
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Discussion Starter · #10 ·
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.
 

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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
Fumed Colloidal Silica (also known as CAB-0-SIL)
For use when an extremely hard solid with high density is needed. A small amount of Colloidal Silica ( about a tablespoon per 4 ounces) will add strength to a top coat but still finish absolutely clear. The white color in the mixing cup will disappear when it cures.
West Systems
Graphite Powder is a fine black powder that can be mixed with epoxy to produce a low-friction exterior coating with increased scuff resistance and durability. Epoxy/graphite is commonly used as a bearing surface, and as a coating on rudders and centerboards, or on the bottoms of racing craft
Ted Moores, 1997 edition of Canoecraft
25% graphite, 5% silica, and 70% epoxy for a rock-hard finish.
 

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B.S.
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Discussion Starter · #12 ·
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.


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
Fumed Colloidal Silica (also known as CAB-0-SIL)
For use when an extremely hard solid with high density is needed. A small amount of Colloidal Silica ( about a tablespoon per 4 ounces) will add strength to a top coat but still finish absolutely clear.  The white color in the mixing cup will disappear when it cures.
West Systems
Graphite Powder is a fine black powder that can be mixed with epoxy to produce a low-friction exterior coating with increased scuff resistance and durability. Epoxy/graphite is commonly used as a bearing surface, and as a coating on rudders and centerboards, or on the bottoms of racing craft
Ted Moores, 1997 edition of Canoecraft
25% graphite, 5% silica, and 70% epoxy for a rock-hard finish.
 

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

From another thread...

Coat the bottom in an epoxy graphite mix! I did it for bottom protection on my boat when I was building it, and after running aground on several oyster bars I will never own another small boat without doing it!

Get some good, slow cure epoxy (4:1) and powdered graphite and mix it at a ratio of about 4 to 1, or 20-25% graphite. Run it through a paint strainer before rolling it on. Tape off your bottom very well cause this will make a mess and it hard to remove once cured.

I applied mine before paint, here is a pic of when I was masking off to apply the topcoat.
 

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B.S.
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Discussion Starter · #14 ·
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.
 

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B.S.
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Discussion Starter · #15 ·
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
 

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B.S.
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405 Posts
Discussion Starter · #16 ·
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!!!!!!
 

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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.
 

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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.
 

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B.S.
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Discussion Starter · #19 ·
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.
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. :-/
 
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