A truly back to the future product. The early seafarers discovered that copper was an ideal coating for the bottoms of their ships to beat the teredo worms and the seaweed and barnacle which so slowed them down or destroyed their ships. Their only way to apply it was to nail thin copper plates all over the bottom of their wooden ships. Now we have a much better way, Cop-R-Bote. Ultra fine copper powder mixed into an epoxy resin. You paint the copper onto the bottom of your boat. It will last for years and years. Sadly, like every other antifouling system, it is not a magic bullet. It is less active than some of the ablative antifoul paints. As a result, the bactereial slime will start to lodge on the coating. This needs to be wiped off with a scotch brite pad now and then, or it will shield the copper which will allow the animals (barnacles and mussels etc.) to get started and the vegetatitive stuff (weed) to hang on. How often, well it depends on the water temperature and the nutrient in the water and the degree to which the bugs have gotten used to being poisoned by heavy metals. Mostly only every couple of months, but in North Queensland, perhaps a bit more often.