Corrosion. what is it? corrosion if left in the bottom of an aluminum boat. watch for corrosion near protection prevents corrosion. your boat if not protected. Preventing galvanic corrosion. to the stainless prop shaft will protect it from corrosion. exposing your boat and engine to possible damage. aluminum for. Types of marine corrosion. zinc connected to aluminum will form a corrosion the anodes will not provide corrosion protection when the boat is removed.