Instructions from manual
The following is from the 1977 C22 manual, available online at (http://www.catalina22.org/manuals/mnl77/manl77.htm#swingkeel):"You'll face special problems if you decide to keep your retractable keel model in the water, especially salt water. Bottom paint is a must, plus periodic cleaning and removal of marine growth from the keel trunk slot. The possibility of corrosion to the keel and keel fittings is greatly increased. Keeping a retractable-keel model in salt water for lengthy periods is not recommended. Should you decide to keep a retractable-keel model in the water at a slip or mooring, the following suggestions may help to extend the life of the keel assembly. First of all, the keel pivot pin is made of silicon-bronze, the hinge castings are of brass, and the keel itself is made of steel. To retard electrolytic action which will "eat" away the metals, drill and tap the side of the keel (near the forward edge) as close to the keel pivot assembly as possible. Then attach a teardrop shaped "zinc." Keeping the keel in the raised position will help prolong the life of the flexible stainless steel cable by keeping as much of it out of the water as possible. Replacement cables are available through the local dealer. Paint the keel itself with rust retardant paint like the commercially available "Rust-o-leum" or zinc chromate paints. If you use a zinc chromate paint, you must strip the keel down to bare metal before painting. Paint the keel and fiberglass bottom (including portion of rudder that is underwater) with a good quality "hard finish vinyl-based" bottom paint to protect the fiberglass gel coat and reduce fouling growth. The through-hull fittings are installed so that there is very little, if any, metal exposed to water to be acted upon. Your local dealer may have additional suggestions relative to the particular area where you plan to keep the boat."Hope this helps. I'm new to the C22 myself.