Yes it is water based and rollers are easily cleaned on water. On the third day of applying in Trinidad a big black cloud appeared and unloaded on us. It washed the two coats we were applying to the final third of the boat. The other two thirds applied on the previous two days was untouched. We had enough to complete the job in the end!
I wasn't aware that Coppercoat eroded at all. To bring fresh copper to the surface you have to lightly sand the hull with an 800 grit paper. Check the barrier and eroding facts with Coppercoat - I'd be interested to know.
In the tropics we have a light coat of slime build up on the hull over a couple of months. I use a stainless wire wool to scrub it or a large scraper. I can do most of the hull with just a mask and snorkel. In home waters -Wales and Scotland - the build up was less (this with the old Coppercoat), but it hosed off quite easily with the boat dried out against a harbour wall.
It works for me, and the main thing I like is a very smooth hull, none of the peeled onion skin effect after a few years build up of eroding anti fouling. Oh, and I don't have the messy annual job of reapplying anti fouling.
Ocean Hobo SN96