ANODE SHAFT 70 mm.

Function and technical context

Shaft anodes are part of a vessel's cathodic protection system, acting as a sacrificial mass to preserve submerged metal components from galvanic corrosion. This 70mm zinc anode is installed directly on the tailshaft, protecting it along with the rest of the driveline: horn, propeller and flying buttresses. Galvanic corrosion is especially aggressive in marine environments, where the presence of two different metals in contact with electrolytic water generates currents that destroy the less noble metal; the anode is sacrificed instead. Without adequate cathodic protection on the shaft, the stainless steel or bronze of the drive line can suffer pitting and severe degradation that would compromise the structural integrity of the transmission.

When to replace this part?

The clearest indicator that the shaft anode has reached its useful life is the reduction in its mass by more than 50%, at which point its sacrificial capacity is compromised and it no longer effectively protects the shaft and propeller. It is recommended to check all zinc anodes at each seasonal beaching - at least once a year - and replace them preventively if they show pronounced wear, uneven surface or fragmentation. Changing the anode before it is completely consumed is the most economical measure to avoid costly repairs to the shaft, horn or propeller caused by electrolytic corrosion.