I used CopperPoxy
on my boat several years ago. It is somewhat "peanut buttery" in texture, and must be mixed, thinned, and stirred carefully (as per instructions). After trying a roller, I ended up applying and "tipping" it by brush. It's difficult to get a real smooth finish and is a bear to sand smooth. When it sets up it is like having a coat of metal on the bottom of your boat, though blisters will still come through if the hull has wet spots. $2 worth of quarters at the car wash takes off what growth has accumulated (not much) in a year's time (fresh water). Instructions say to scuff it with ScotchBrite once a year to expose the copper. The manufacturers claim 10 year life, and I believe it. About $275/gal last time I checked. I'd use it again because it lasts so well and the job is so labor intensive.
