And another vote for Jotun, I have used Jotun for 20 years the seaforce 30 is the best, the seaqueen I found not as good, but its more expensive. I have kept my boat in Holland, the Hamble river uk, and France, so it stands the test of different areas.
I use 2.5lt of thinned down on a 38 and its great, I thin it down because its hot when I antifoul. lifted out at the moment and the boat had a slime on it apart from the water line which had green growth for about 4" down.
I do not antifoul every year, just do around the waterline. This time it has lasted 3 seasons.
Uk is the worst area especially the Hamble river.
Odysseus