Originally Posted by overthehorizon
colemj, you are making me feel better about my aggressive sanding of the Coppercoat, which is contrary to the Coppercoat instructions. At least I will know the copper is well exposed. The only time I used such fine sand paper, of 320 or 400 grit, was finish sanding on the smoothest top side surfaces in preparation for gloss paint. Coppercoat recommends those sanding grits to activate the copper in the Coppercoat. That might work on a glass smooth finish but I have never seen a Coppercoat application that smooth. All applications I have seen are very dimpled, even when using the finest, smoothest, rollers, applied by professionals. That is why we went back with the green scrubby and wet sanded to try to get even more into the valleys of those fine dimples, and etch those surfaces. I do wonder what would happen, on a future haul out, if you should sand the Coppercoat a bit more aggressively, if that would expose more copper and increase performance.
I don't know how ours was applied, but it is very smooth. Like it was laid up in a female mold. Maybe it was sprayed, or maybe they just sanded it very good. I don't know why you think that is contrary to Coppercoat instructions. The instructions I have say the surface should be smooth and sanded to look like a new penny all over. People I know that left the application dimpled from a roller have had bad results with antifouling.
Before we launched, we sanded it again with the grit paper recommended by Coppercoat and reactivated the surface. I doubt doing again would give better performance. It is the copper oxide (green) that is the biocide, not the metalic copper (copper color). The whole point is to not have to haul it every year and sand it hard.
No, I think our application was perfect, and the Coppercoat is working as well as it can. That is to say, it is better than nothing, but not as good as purposed antifouling paints. However, it will work this modest way for a long time, but will need more frequent maintenance than painted hulls.
We will keep and monitor it for at least another year or two, because redoing the bottom is very low on our project list. The upside is that nothing will need to be done to the bottom to apply antifouling paint over it.