Poly removal/repair advice
- Thread starter BamaBill
- Start date
Richard Buhr
Member
Bill,
Another option would be to coat the bottom with an epoxy/cabosil/graphite mix. If you've got a good solid gel coat base you shouldn't have any problems. I've done this on half-dozen new boats and several repairs. It gives you a very slick, hard coating. The one downside as with any epoxy is low resistance to UV damage. If you're storing the boat hull side up in the sun it's not a very good idea.
Some people claim the graphite adds UV protection. I can't speak to that. If you're just trying to fill scratches etc., I would prep sand with 80 grit paper. I've always taped off at the waterline.
First coat with a mixture of epoxy/cabosil. Mix the epoxy/hardener then add the cabosil/graphite to the consistency of pancake batter and apply with a foam roller. Then take a foam brush and tip it off. Basically, tipping is lightly draging the foam brush over the just rolled epoxy/cabosil to smooth it and eliminate any air bubbles. Usually work a section at a time. Let dry overnight or until it's just a little tacky. For the finish coats, I like to use a 60/40 mix of cabosil/graphite. I keep a separate container that I've mixed 6 oz. of cabosil with 4 oz. of graphite. The cabosil is kinda lumpy and it's a lot easier to premix it up with the graphite then adding the two separate fillers to your epoxy. Typically start with a 12 oz. batch of epoxy and mix in 4 oz. of the cabosil/graphite mix. Gives you about 1/3 fill to 2/3 epoxy.
Some guys will go as high as 40% fill. As mentioned roll and tip a section at a time. Usually apply three finish coats of cabosil/graphite over the base coat of cabosil/epoxy. These are fairly thin coats and that mixture should cover approximately 35 – 40sq. ft. As long as you're able to do your coats within 24 hours of the previous coat no additional steps are required. If I had to wait longer than 24 hours to recoat I would wash the hull with soap and water, rinse with clear water and then very lightly sand with 80 grit. This will remove any amine blush that could occur. I've read of guys going as long as 72 hours without washing and sanding but I certainly wouldn't take the chance.
It seems to me that Brad Taylor applies a similar mix on his boats with a brush. You can load the brush and put down a heavier coat than a roller. You might check with him as he certainly does a great job on his boat builds.
When the mixture dries, you'll have a very hard, glossy black finish. You can lightly sand the hull with 150 grit paper and end up with a satin gray color. I do have a couple boats that I've painted over the epoxy duck boat colors for camo and UV protection when they needed to be stored hull side up.
Here's a link showing someone else's steps. tomangelakis.tripod.com/graphite_bottom.htm
As Tod mentioned, another option is a Kevlar and fiberglass re-skin. My experience with 5 oz. Kevlar is that it takes as much resin to wet out the Kevlar as it does to wet out 17 oz. biaxial glass. That stuff is a sponge! And it really does fuzz. I've had some luck removing the fuzz with a Dremal set on high and a fine, round sharpening stone.
Fiberglasssupply.com has graphite and cabosil for a good price.
Hope this helps and if you have any questions feel free to e-mail. In fact, if you don't mind I would like to see some pictures of your project. I pm’ed my email to you.
Good luck.
Richard
Another option would be to coat the bottom with an epoxy/cabosil/graphite mix. If you've got a good solid gel coat base you shouldn't have any problems. I've done this on half-dozen new boats and several repairs. It gives you a very slick, hard coating. The one downside as with any epoxy is low resistance to UV damage. If you're storing the boat hull side up in the sun it's not a very good idea.
Some people claim the graphite adds UV protection. I can't speak to that. If you're just trying to fill scratches etc., I would prep sand with 80 grit paper. I've always taped off at the waterline.
First coat with a mixture of epoxy/cabosil. Mix the epoxy/hardener then add the cabosil/graphite to the consistency of pancake batter and apply with a foam roller. Then take a foam brush and tip it off. Basically, tipping is lightly draging the foam brush over the just rolled epoxy/cabosil to smooth it and eliminate any air bubbles. Usually work a section at a time. Let dry overnight or until it's just a little tacky. For the finish coats, I like to use a 60/40 mix of cabosil/graphite. I keep a separate container that I've mixed 6 oz. of cabosil with 4 oz. of graphite. The cabosil is kinda lumpy and it's a lot easier to premix it up with the graphite then adding the two separate fillers to your epoxy. Typically start with a 12 oz. batch of epoxy and mix in 4 oz. of the cabosil/graphite mix. Gives you about 1/3 fill to 2/3 epoxy.
Some guys will go as high as 40% fill. As mentioned roll and tip a section at a time. Usually apply three finish coats of cabosil/graphite over the base coat of cabosil/epoxy. These are fairly thin coats and that mixture should cover approximately 35 – 40sq. ft. As long as you're able to do your coats within 24 hours of the previous coat no additional steps are required. If I had to wait longer than 24 hours to recoat I would wash the hull with soap and water, rinse with clear water and then very lightly sand with 80 grit. This will remove any amine blush that could occur. I've read of guys going as long as 72 hours without washing and sanding but I certainly wouldn't take the chance.
It seems to me that Brad Taylor applies a similar mix on his boats with a brush. You can load the brush and put down a heavier coat than a roller. You might check with him as he certainly does a great job on his boat builds.
When the mixture dries, you'll have a very hard, glossy black finish. You can lightly sand the hull with 150 grit paper and end up with a satin gray color. I do have a couple boats that I've painted over the epoxy duck boat colors for camo and UV protection when they needed to be stored hull side up.
Here's a link showing someone else's steps. tomangelakis.tripod.com/graphite_bottom.htm
As Tod mentioned, another option is a Kevlar and fiberglass re-skin. My experience with 5 oz. Kevlar is that it takes as much resin to wet out the Kevlar as it does to wet out 17 oz. biaxial glass. That stuff is a sponge! And it really does fuzz. I've had some luck removing the fuzz with a Dremal set on high and a fine, round sharpening stone.
Fiberglasssupply.com has graphite and cabosil for a good price.
Hope this helps and if you have any questions feel free to e-mail. In fact, if you don't mind I would like to see some pictures of your project. I pm’ed my email to you.
Good luck.
Richard
Last edited:
BamaBill
Active member
Well, due to moving back to north Alabama, and remodeling a house, organizing my new shop, etc....this project has gotten back-burnered for a while. At least I have a covered carport section, as well as a heated (once I install the heaters) shop space to work in....I may be able to finish out the removal/sanding/smoothing shortly, and be ready to apply some cabosil/graphite/epoxy mix to the entire bottom....unless I do add a layer of say 6oz glass, just as a precautionary? In either case, how much cabosil, graphite, epoxy, glass, etc. should I count on to cover a 16'Lx52"W, gheenoe-shaped bottom, only? Should I use a fast set epoxy hardener, since I may be talking of working in moderate winter/spring temps? Do I need pumps, rollers, etc., or can I get by with self-measuring, foam paint rollers/brushes, plastic trowels, etc...from my local hardware? Thanks again for all the pointers.