On my C36, I get about 8-10 months out of my sharft zincs. With the warm water we have here in Galveston Bay, I just hop in and check them out. If they need to be replaced, I have a 6' length of water hose I use as my breather tube - I tye-rap the other end to the swim ladder. I also have a brush and a scraper which I use along with a pair of dive goggles to make sure my bottom and propeller are squeaky clean. Gives me a pretty good workout! Russ