We may very well have this boat a long time, I just want to do whats best for it. Nowhere do I read any technical articles that zinc is better in brackish water, I read just the opposite, the only promotion of zinc over aluminum are the arguments like "that's what we always have done". I've heard of different anodes before but never concerned myself with them but our present boat cost more than all my previous boats combined. I've had some real adventures trying to disassemble old outdrives and lower units, I wonder how much easier some of those jobs might have been if they were protected with aluminum alloy.
To put it another way many cars were produced without oil filters way back when, those kind of caught on too.
I'm pretty sure your C320 doesn't have an outdrive to worry about, so that's not a particularly accurate analogy, and neither is the cars without oil filters.
The facts I see in evidence are there are thousands and thousands of 30+ year old sailboats on the Chesapeake that have had no issues using zinc anodes.
@Faster, cheaper they may be, but I know it would take time and effort for me to find them and I'd most likely have to pay shipping to get them, so being that I have no problems "doing it the way they've always done it" I guess I'll keep doing it, and not look for a better mousetrap.
Finally, I agree with Chef, that if I saw evidence of stray current (or was just worried about it) at my marina, I'd invest in a galvanic isolator, especially if I planned to keep my boat plugged in.