Zinc Anode

A zinc anode is a sacrificial anode bolted or welded to a steel hull, rudder, propeller boss, or internal tank to provide cathodic protection against galvanic corrosion. Zinc sits below steel in the galvanic series, so in seawater it corrodes preferentially and supplies protective current to the steel, which stays cathodic and intact. Zinc suits seawater; aluminum and magnesium anodes serve brackish and fresh water respectively. The anodes are consumed over time and replaced at drydocking. The alternative is an impressed-current cathodic-protection (ICCP) system using an external DC source.