Catalytic corrosion is caused by a voltage difference causing current through the water. Different submerged metals in near contact can cause this. Most often the problem of excessive corrosion is caused by an incorrect ground. Do not leave your shore power cable connected if not in use. Do not leave a shore power battery charger "maintaining" your batteries. These two steps should eliminate most of the problem. Without a current there will be no corrosion. The hard work is finding where the bad cable or connection is allowing voltage to ground and "fueling" the corrosion process. Good luck.