I don't think there is a really good
way to prevent growth on your prop and shaft. What I suggest is walking around your boat yard and looking at what other boaters have done to protect their props/shafts in the kind of fouling waters your boat lives in. I have a bronze shaft and prop, for example. Each year I spray them with Interlux Primocon primer and then put on two coats of whatever modified hard epoxy bottom paint I happen to have around. This "sort of" works, that is, by the end of and 8-month season on the Chesapeake, a moderate fouling area, most of the paint has worn off and I usually have a half-dozen or so barnacles on the prop. I really don't think I could do much better than this unless I wanted to get in the water now and then and scrape -- and I don't want to.