ANODE SHAFT 5

Function and technical context

The shaft anode is a cathodic protection element designed to be mounted directly on the tail shaft of the vessel, acting as a sacrificial metal that preferentially corrodes to protect the noble metal parts of the propulsion system - shaft, propeller and horn - against galvanic and electrolytic corrosion. It works within the underwater transmission system, in the area most exposed to salt or brackish water, where the difference in electrical potential between different metals can generate accelerated and invisible degradation. Its role is critical: without good anodic protection, the stainless steel shaft and bronze or aluminum propeller can suffer from pitting, structural weakening and premature failure that compromises the integrity of the propulsion line.

When to replace this part?

The clearest symptom that the shaft anode has exhausted its useful life is the visible reduction in its mass: when it has lost approximately 50% of its volume, it must be replaced immediately, since its protective capacity is compromised and the shaft is exposed to corrosion. The review and inspection of the shaft zinc anodes must be carried out at least once a season, coinciding with the annual beaching, and in vessels that navigate in areas with high electrical conductivity of the water (ports with dispersed currents, brackish waters) an intermediate inspection in the middle of the season is recommended. Replacing the shaft anode preventively, before it is completely consumed, is the most economical measure to avoid the repair or replacement of a tail shaft or propeller, interventions whose cost far exceeds that of a simple anode replacement.