Ceyenne peper could be worth a shot. Maybe chilli even. But I strongly disagree with the thought of putting an anti-biotic like tetracyline and tectracycline into the stuff. Firstly, anti-biotics won't kill marine growth. You need fungicides for that. But my main concern is allowing some other "life form" to be in such close and long term contact with an anti-biotic. Who knows what they may become immune to, or more importantly, make us allergic to. Think hat a little far fetched?? well a major marine paint company was playing with similar thoughts about 15 to 20years ago. There was strong opposition to the idea then. I personally have no clue if something nasty could be breed, but I just remember all the hoohaa back then, by the guy's that were supposed to be in the know.
Back to the paint though. Micheal applied 7 coats. I would suggest it was the thickness applied that has been the biggest factor in it's success. An ablative paint works three ways. Firstly it wears away. But it is also very porouse and slowly leeches out a poison, called biocide, that kills weed growth. Other additives, often copper oxide, leaves a nasty taste in the little fellows mnouths, when they try to cling on. If the paint is applied thick enough, this Paint "sponge" will hold alot of the nasty stuff to do the work a considerable time. However, ther can be a problem with application like this. The paint as it comes to the end of it's life, starts to shrink. Thus it starts cracking and becomes like orange peel in apperance. Large chunks can come off leaving a very rugged surface on the hull
. There is only one way to solve the problem. Somwhere along the track, a major sand down is required. With applying two to three coats, you can often get 2 seasons out of a job. One to two coats will give a good season. Although I have to clarify hear, it depends on water temp, whether the salt
water gets flushes of fresh regularly, and what the ability of the paint is like in the first place. But back to the number of coats. With ablative coatings, they wear away slowly. This is a benifit to when the time to recoat comes as much of the preperationm has already been done for you. A good hard water blast will often be enough. Do ensure you get as much off with the water blast as you can. Leaving too much of the old dry worn out paint will only do the same. Crack and flake off.
Remember, we only want to kill off or keep off the growth on the hull only. When Tin based anti-fouls were around, the hulls had never been cleaner. But the marinas
and harbours were all dead worlds. It has taken some years for some places to come back to life. But it is so fantastic to sea such an abundance of Marine life in the Marinas