Cathodic protection is the process of reversing the corrosion current to stop the damaging corrosion process. Cathodic protection is achieved by placing a type of metal into the water with the boat and connecting it to the boat’s metallic parts. A metal such as zinc or aluminum that is less noble than the other metals on the boat will act as the anode when connected to the metal parts of the boat. All boats are equipped with zinc anodes that are typically mounted to the hull or prop shaft or rudder, etc. of the boat. These zinc anodes are designed to protect the boat from galvanic corrosion.

However, when these zinc anodes corrode they lose their ability to provide sufficient protection to the metal parts of the boat that are submerged in the water. Zinc anodes need to be replaced often to keep corrosion at bay.

Oftentimes, when boats become older and paint on metal parts deteriorates, the zinc anodes are no longer sufficient to provide the degree of protection required. Also, when galvanic corrosion occurs between boats in marinas the zinc anodes usually are not sufficient to counter this type of corrosion attack as well. A common symptom of these problems is when the zinc anodes on a boat corrode quickly.