I'm assuming he has a cast iron centerboard? My Catalina 22 also has an iron swing keel, and I installed this on it after drilling and tapping holes in the keel: https://www.catalinadirect.com/shop-by-boat/catalina-25/hull-deck/maintenanc... If there isn't clearance for one that large, you can get small zincs made for outboards. Sincerely, Tyler ----- Original Message ----- From: "For and about Montgomery Sailboats" <montgomery_boats@mailman.xmission.com> To: "For and about Montgomery Sailboats" <montgomery_boats@mailman.xmission.com> Cc: "john" <john@eco-living.net> Sent: Wednesday, February 8, 2023 5:37:45 PM Subject: M_Boats: Sacrificial zinc on M17? Hi all, Posting this for Keith K, who is having some kind of trouble posting to the list at the moment. His question is: "Have other M owners put sacrificial zincs/aluminum on there boats? If so where? My boat stays on a mooring now for 4-5 months, full on salt water." cheers, John -- John Schinnerer - M.A., Whole Systems Design -------------------------------------------- - Eco-Living - Whole Systems Design Services People - Place - Learning - Integration john@eco-living.net - 510.982.1334 http://eco-living.net http://sociocracyconsulting.com