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Barrier coating

748 Views 5 Replies 6 Participants Last post by  MakoMatt
A buddy of mine is preparing his boat (an older Grady) boat for a new application of bottom paint..He is going to go with a high quality ablative
paint. About 75% of his hull is down to
the gelcoat with maybe a deep nick here
and there. Is a coat of barrier coat on
the bare stuff a good idea???
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flynny7, you didn’t mention anything about blistering, only that the hull has a nick here, or there. The barrier coat systems are designed for hulls with gel coat problems, i.e., blistering. Stay away from it, you don’t need it. As a side note, I would like to say that the barrier systems do work, however, they are extremely labor intensive, and you must follow the instructions 100%. The is a lot of preparation work involved and if the boat is kept outdoors, you need a very good long weather window which is often difficult to find this time of year.

If you have already removed 75% of the bottom paint, you may as well go for it and remove the rest. Fill any of the gouges with MarineTex, and fair with sandpaper accordingly. You can purchase small cans of gel coat if you want to cover the MarineTex if you like, but it is not necessary.

After the paint is removed, wash the underside hull down with soap and water, rinse well. Interlux has some solvents that you can then wipe down the hull with to remove any soapy, wax residue.

It is now time to paint the bottom. You may have noticed that I didn’t mention anything about sanding the bottom, to give it some “grip” as others have mentioned. I would not recommend doing this. Fiberglass and gel coat are porous and will absorb water. The gel coat is very thin, why wear it down? If the old paint didn’t come off that that would tell me the surface is “rough” enough to accept paint. If you are concerned about it, use the Interlux No-Sand Primer. The purpose of this product is so that you DON’T have to sand. I know you want to do the right thing, but don’t get anal about it, it’s the bottom of the boat. As far as paint, I would recommend Interlux Micron 2000, it’s just about the best on the market right now. Use 2 coats, each a different color. Next year you only touch up where the 1st. color is visible.

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