Re: Anti-Fouling Paint on an outboard?
+1 on what PDQ said.
Yes, you can kill the critters that WILL grown in your cooling passages by running the engine hot enough for long enough. BUT, the dead critters will still be there, latched onto the metal, and the only way to get them out is acid washing - with an inhibited acid of course.
Talk to a local yard that does outboard work, and ask them.
s/v My Sweet Girl!
Catalina 30 (Mark I)