After I had my boat hauled out and pressure washed I noticed patches of bottom paint flaking off down to the gelcoat. If I take all the bottom paint off (fun job) should I use a barrier coat or just bottom paint? Hearing mixed answers.. Thanks, John
If your planning on keeping the boat long term it's a nice way togo, but keep in mind it's a lot of work, several steps and not cheap. You may just want to have the bottom soda blasted and put a good fresh bottom paint on it.
On one of my old boats i had the same problem as you. If you want to get away with it this season sand the areas that are peeling all the way down to the original primer in that section. Apply barrier coat to that area. The trick is you want the barrier coat to over lap the old primer not the paint. I did that and it was fine for that season. The best route is to soda blast it. I cant say enough for the interlux system. I did it on my last two boats. Last year i had the bottom blasted and applied the full system myself. Boat just came out of the water after 12 months of being in the water. Paint looked as good as the day i applied it 12 months ago without any growth on it.
One thing you may also want to try is pressure washing the paint off. My dad couldnt get the soda blasting guy up here in NY in time to do his sea ray. He took his pressure washer to it and about 90 percent of the paint came right off. A little sanding and the boat was ready for barrier coat and paint. He was lucky that the dealer did a poor job on the bottom when he bought it 6 years ago.
If you want to keep the boat a long time and are stripping it anyway. You rerally want to think about doing the barrier coat. When I did it it was 5 coats, now they say you do not nee as many. Once the bottom is clean andmaybe sand light to rough up. Get ready and mix. It is 2 part so mix what you need and apply quickly. It is a lot of prep and clean up. It is a 2 part epoxy that will seal the outer part of the hull. You can still get penetration inside.
unless your showing signs of blisters don't do it. In order to do the barrier the right way you need to aggressively sand or blast the gelcoat. That usually compromises the original bottom finish ,then you have to barrier coat it . By the way that still doesn't cure the blister problem.
Never said barrier coat was a bad thing. What I'm saying it's about the physics of fiberglass. Fiberglass is considered raw unitl the gel coat is applied which contains wax that cures the outer layer which is usually exposed to water. Once the gelcoat is damaged, water peneterates the raw fiberglass and creates blisters and worse osmosis. So you fix the damages ,dry the hull, check it with moisture meter,barrier coat the bottom. Take a look at your bildge. Wet?
Moisture is absorbed by raw fiberglass in the inside of your hull. Unless you specify you want the inside of the hull gelcoated when being built, that's what you get. Since barrier coat is an epoxy the moisture then becomes trapped in the raw fiberglass inside the hull and and hence more blisters.I've seen blisters seperate the barrier from the hull after time. Barrier coat does not cure the problem,it just keeps more moisture from entering from the water side of the boat. So until the boat manufactutures start using straight epoxy resin on hulls you'll have blisters.
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