Anodes to protect against galvanic corrosion. No metal is completely immune to corrosion. Therefore, metal components of ships and offshore elements must be protected. We usually do this with an anode, also called a sacrificial block. Because the anode is made of a different metal than the metal it is attached to, it rusts away first. The anode sacrifices itself. If an anode is not rusted after a sailing season, it will not work! As soon as the anode has rusted away, the metal to be protected will rust. Anodes must therefore be replaced regularly.