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Repairing chips/holes in gelcoat...

jacksonkev

Member III
I’ve got a few chips/holes in my gelcoat along my toe rail. I was going to repair them with a thick mixture of West System epoxy. But then I started to get that second guessing feeling. The holes are on a vertical surface...I’m starting to imagine the goop running out if I can’t get the mixture just right.

So, my question...what’s the proper way to tackle this?

Thanks in advance!

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toddster

Curator of Broken Parts
Blogs Author
I think that would work OK. See the West Systems manual. It doesn’t look deep enough to require fiberglass reinforcement. You might want to feather the edges of the hole a bit. Anyway, thickened epoxy worked on a couple of topsides gouge repairs that were more than vertical.
 

JPS27

Member III
if it's not structural and it's vertical as this seems to be, why not use 3m Premium Filler or something similar? Cures fast, accepts gel coat, but what I like most is easy to sand. I like to always qualify, I'm no expert. But I have done several repairs like this and learned a few lessons.
 

jacksonkev

Member III
I think that would work OK. See the West Systems manual. It doesn’t look deep enough to require fiberglass reinforcement. You might want to feather the edges of the hole a bit. Anyway, thickened epoxy worked on a couple of topsides gouge repairs that were more than vertical.

Kind of what I was thinking...mix it up until it's like peanut butter, fill it, scrape it flush, sand it, paint it (maybe).
 

jacksonkev

Member III
if it's not structural and it's vertical as this seems to be, why not use 3m Premium Filler or something similar? Cures fast, accepts gel coat, but what I like most is easy to sand. I like to always qualify, I'm no expert. But I have done several repairs like this and learned a few lessons.

Thanks for the suggestion...I'm not familiar with 3m Premium Filler, how does it differ from a thick batch of West System epoxy? I was planing on sanding the epoxy with 220 then something closer to a wet sand then touching it up. Then again, I don't have much experience with this technique either.
 

toddster

Curator of Broken Parts
Blogs Author
You will need to paint it, or the epoxy will get yellow (and brittle?) on exposure to sunlight.
 

tenders

Innocent Bystander
Marine Tex, West System, and other epoxy products are tough to use for this purpose because they’re significantly harder than the surrounding gelcoat and fiberglass. When you try to sand them smooth, those areas will stand proud of the surrounding fiberglass like a welt. You can soften the epoxy with additives but it is really hard to get this right, and the color will be way off.

The 3M filler is premixed to a useful viscosity, is made of polyester, not epoxy, and will sand smooth. It also cures quite quickly. That’s the stuff to use for a fix like this, and then paint at your convenience.
 

markvone

Sustaining Member
I second what Tenders suggested. All you need is a filler so the gelcoat is not super thick (which tends to shrink and crack). Not structural and you don't want to damage the surrounding gelcoat sanding hard epoxy. I'll use thickened epoxy for holes in horizontal surfaces where I have good control over the fill level and can leave space for gelcoat and not go proud of the gelcoat surface to avoid sanding.

If that black area is not over 1/16 inch deep I'd be tempted to go straight to gelcoat. I'd wet sand the brown spots to see if they come off first. Gelcoat is pretty thick, but I believe you can also get a gelcoat paste that should have less tendency to run for vertical surfaces or Google how to thicken gelcoat.

Even a horrible color match for that spot will only be visible from two feet away and only by you. It will look ten times better than the black chip looks now. The practice with color matching gelcoat will be secondary benefit of the job.

Mark
 

jacksonkev

Member III
Marine Tex, West System, and other epoxy products are tough to use for this purpose because they’re significantly harder than the surrounding gelcoat and fiberglass. When you try to sand them smooth, those areas will stand proud of the surrounding fiberglass like a welt. You can soften the epoxy with additives but it is really hard to get this right, and the color will be way off.

The 3M filler is premixed to a useful viscosity, is made of polyester, not epoxy, and will sand smooth. It also cures quite quickly. That’s the stuff to use for a fix like this, and then paint at your convenience.

Thanks, Tenders!
 

jacksonkev

Member III
I second what Tenders suggested. All you need is a filler so the gelcoat is not super thick (which tends to shrink and crack). Not structural and you don't want to damage the surrounding gelcoat sanding hard epoxy. I'll use thickened epoxy for holes in horizontal surfaces where I have good control over the fill level and can leave space for gelcoat and not go proud of the gelcoat surface to avoid sanding.

If that black area is not over 1/16 inch deep I'd be tempted to go straight to gelcoat. I'd wet sand the brown spots to see if they come off first. Gelcoat is pretty thick, but I believe you can also get a gelcoat paste that should have less tendency to run for vertical surfaces or Google how to thicken gelcoat.

Even a horrible color match for that spot will only be visible from two feet away and only by you. It will look ten times better than the black chip looks now. The practice with color matching gelcoat will be secondary benefit of the job.

Mark

All good advice...and you're right, the chips (once covered) will be fairly hard to see on the toe rail. I think I'll fill 'em with something easy to sand then match some gelcoat as close as I can and call it good. I mainly want to stop the water from running down into my cabin/hull. So, I need to do it sooner than later.
 

sharonov

Member II
Marine Tex, West System, and other epoxy products are tough to use for this purpose because they’re significantly harder than the surrounding gelcoat and fiberglass. When you try to sand them smooth, those areas will stand proud of the surrounding fiberglass like a welt......

I have a solution for that. Use Dremel with 565 cutting guide. Works wonders. Need to remove that bump of thickened epoxy ? No problem, just set cutting depth flush with gelcoat surface. Need to dig into it a bit to create shallow pocket for a new gelcoat? Set cutting depth about 30mils below the surface and then taper/feather the edge by hand. Whatever bits came with the kit may or may not work well. I just use a milling bit purchased separately.
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tenders

Innocent Bystander
Well, good luck maneuvering that around the obstacles surrounding most gelcoat repairs...including this one.
 

JPS27

Member III
3M marine premium filler is made for filling gouges etc on top of which you'll put gelcoat. Once activated it is already a paste like substance. It starts curing within minutes though so you need to be set up to immediately apply. But gelcoat will go on either the 3m filler or your epoxy. I've done it both ways. And it's held up both ways. I have a thread on here somewhere where I got good advice from folks. I used the filler for gouges, and thickened epoxy for a small hole in my toerail. I've also done just gelcoat for minor scratches. It's hard to tell from the picture but yours might require just a couple of coats of gelcoat. I prefer to go with gelcoat and not paint at this point. I just would rather learn how to use gelcoat than change to paint.
 
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