Hey cmjeff, what type of hull???
I never seen any difference in growth from hulls where they used cyan pepper mixed in paint, my theroy is it gets dilluted in the biga$$ body of water it's in.
The "ablative" paints, in theroy, gradually wear while under way, and inhibit the barnacles from "seeding" to the boat. Well it only takes 24 hours for a barnacle to do this and be seen with the naked eye. So running the boat often would be best for that option.
I don't remember anything about Tin in paints that we used at the ship yard 100 or so years ago.
If he can make it/ or not to clear waters, I would just get used to taking it out and diving the bottom frequently to maintain.
I like to check all intakes frequently.
Interlux and petit make a clear antifouling paint he can use on the sea strainers.
I'm not up with the industry like I used to be, but I would contact the manufacturer, they don't spend millions on research to have thier product fail.
Some paints require a pesticide certification and license for application. Thats where the small boat yards stick ya.
I would come and do it, but plane tickest and beer would get expensive.