I’ve always liked the versatility that comes with a centerboard. The ability to vary your boat’s draft from deep to shallow greatly increases the options you have when cruising. The other side of the coin is maintenance.
A centerboard can be made of anything from foam or plywood sheathed in epoxy to solid bronze or cast iron. The former will need fresh antifouling each year. The latter will demand to be stripped down to the bare metal and refinished every three or four years, and once in a great while it will want to be dropped out of the boat so the pivot pin and/or the lifting mechanism can be serviced.
Removing the centerboard on a big cruising boat is no laughing matter. Confronted with a sight like this, I would reach for the trusty angle grinder, bolt on a floppy sanding disk and get that board down to bright shiny metal in next to no time. A couple of coats of epoxy primer followed by your favorite antifouling will get that board looking good again.