Re: (No Through Hull) Transducer
Aboard my powerboat, I spray the paddle wheel with aerosol anti-fouling intended for sterndrives and outboards. It works pretty well. Of course I cruise at 23 knots and often run at 30 kts, so that there is a fair degree of "self cleaning" going on. Your mileage may vary.
Additionally, I usually go overboard with a mask and fins once a month, during the warmer seasons, and check the bottom, including the ducers. I make this task part of the day when we anchor to swim, fish, clam or wade in to the beach. If a growth is occurring, I clean it off ( which of course removes some antifouling paint, so its a double edged sword)
There are two kinds of boaters: those who have run aground, and those who lie about it.