We've had Coppercoat on since 3-2009. So, 3 years so far.
First few months it was not really effective, but once it picked up a bit of patina/oxidation it became more effective. We did a haulout in at 15 months specifically to raise the painted waterline a couple inches adding more bottom paint in that narrow waterline strip. We power washed the bottom at the beginning of the haulout but did not sand or otherwise try to reveal more copper on the hull
Where the newly applied bottom paint was, for the first few months it was not so effective. But, like the older stuff, once it had some patina, it became more effective. Unlike conventional bottom paints which work
great in the first few months following application and then less well, this stuff is the opposite seeming to have to get-in-the-groove before working and it works better after several months.
We have been in the Pacific ocean
temperatures varying seasonally from high 50's into mid-70's depending on where we are sailing.
Presently, we're in the San Francisco
Bay area sitting in a Redwood City marina with a boat just a few slips down which I just learned had Trinidad applied about a year ago. We're new here, but the other boat owner is familiar with the local pests/waters. Both our boats have the same irritating "mud film" which builds up with the silty tidal waters here. He states that's just the "local waters" I dunno... I use a soft bristle brush and a pole and I can smooth it away--it takes no effort--but I'm not happy to see it on the hull! There are no barnacles
or other growth just that silty mud and mostly along one quarter of the boat. A bit later in the spring we'll be anchorage hopping again, and I'll see if my bottom paint does as well as it has everywhere else besides this muddy creek location.
On other boats I've had ablative copper and years ago even TBT bottom paints that have fared no better in Pacific waters. So...???
Not planning on replacing the bottom paint any time soon.