Sacrificial Anode

A deliberately reactive metal component that corrodes in preference to protected underwater metalwork.

The anode is electrically connected to the metal it protects, such as a propeller, shaft, stern gear, drive unit or bonded fitting. Zinc, aluminium and magnesium alloys are used in different environments and systems; the correct material depends on water type, protected metals and the vessel’s cathodic-protection design.

An anode must have clean electrical contact and enough exposed surface to work. It should be inspected and replaced before excessive loss of material, but unusually rapid or absent wear can indicate an electrical, installation or material problem that requires investigation.