Shaft Globe Anodes: Zinc Shaft Anode
Shaft anodes are mounted on the shafts of small leisure vessels to protect the exposed steel prolonging the life of the shafts and propellers. Zinc is the only material that has an official specification, the American MIL-A-18001 K spec. Zinc is a well-proven anode material and its capacity is virtually unaffected by the operating current density, although the driving voltage diminishes with increasing temperature therefore it has limited application. If zinc is not to this specification i.e. high purity zinc 99.99%, it will have a limited use as an anode material because of iron present as an impurity.
Magnesium Shaft Anode
Shaft anodes are mounted on the shafts of small leisure vessels to protect the exposed steel prolonging the life of the shafts and propellers. Magnesium alloy anodes are very active electrochemically, and they are usually recommended only for short exposes or temporary protection and in positions where replacement is easy in seawater. Magnesium alloy anodes are often used for hull protection of fresh water vessels i.e. narrow boats/barges.
