I'm in brackish water (about 50% as salty as the ocean). I get my zincs from boatzincs.com and they recommend using a more active metal than zinc in brackish water - aluminum.
http://boatzincs.com/pdfs/Chart_A-Which_Anodes_Should_I_Use.pdf http://boatzincs.com/pdfs/Chart_B-Which_Anodes_Should_I_Use.pdf About 5 years ago I used 2 extra large zinc shaft anodes and the zinc Max-Prop cone anode. I would stay on shore power and didn't have a galvanic isolator. A good amount of anode would be gone after 1 year. About 3 years ago I installed a shaft dampener which electrically isolates the shaft from the engine. A considerable amount of anode was being left at the conclusion of 1 year. So 2 years ago I shifted to 1 extra large aluminum shaft anode and an aluminum cone anode. Last year's haul out showed about 50% remaining after 1 year so I stayed with that combination. I've also installed solar panels which during the off season and intermittently during the season allow me to stay off shore power. I have stayed on the same dock but moved slips and the number of slip neighbors has changed. Some neglected boats have received maintenance and some maintained boats have gone without. As you can see there are quite a few variables which make dialing in the correct type and number of anodes challenging. I have attempted to learn what disadvantage being "overzinced" holds and since our boats are FRP and I have Marlon through-hulls, no applicable answer was found. Only that it is a waste of money. In my case, it seems far better to error on the side of too much than not enough. As for the shore power connection it is your neighbors who don't have enough anode that are using yours by way of the ground wire in the shore power cable. As for the shaft coupling isolator there is a way to jumper a wire across the coupler but I could find no professional opinion or scientific study which sufficiently convinced me that I needed to install said jumper. The boat is "bonded" to the keel and the keel to the engine. Josh Muckley S/V Sea Hawk 1989 C&C 37+ Solomons, MD On Mon, Sep 25, 2017, 10:46 AM Bruce Whitmore via CnC-List < cnc-list@cnc-list.com> wrote: > Hello all, > > I just wanted to check in with you folks. For those of you who are in > saltwater, on a dock, and plugged into shore power, how long would you > expect to see your shaft zinc last? I get a regular report from our diver, > who, after about 6 months, indicated that the zinc is down to about 70% of > new. > > Thanks for the input, > > Bruce Whitmore > > (847) 404-5092 (mobile) > bwhitm...@sbcglobal.net > _______________________________________________ > > This list is supported by the generous donations of our members. If you > wish to make a contribution to offset our costs, please go to: > https://www.paypal.me/stumurray > > All Contributions are greatly appreciated! >
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