The protection of the underwater metal parts on your boat or motor from corrosive electrolytic action is a very real and necessary concern. The use of an activated alloy such as an anode will help. Anodes will distract the corrosion action to itself and away from expensive metal parts. Fortunately anodes are relatively inexpensive and readily available. Factors such as warm water temperatures, polluted water and stray current corrosion can cause your anodes to waste away at an accelerated rate so it is wise to check them on a regular basis.