ANODE SHAFT 2-1/2

Function and technical context

The shaft anode is a cathodic protection element specifically designed to be installed on the tail shaft of the vessel, acting as a sacrificial metal against galvanic corrosion. It works in the underwater propulsion system, where the shaft is permanently exposed to salt or brackish water, an extremely aggressive environment for metal alloys. By oxidizing in a controlled manner, the anode consumes its own material to protect the stainless steel or bronze shaft, horn closures, and other adjacent metal surfaces. Without adequate cathodic protection, electrolytic corrosion can degrade the shaft, generate play in the thru-hull and compromise the watertightness of the boat.

When to replace this part?

The clearest sign that the shaft anode needs to be replaced is when it has lost between 50% and 60% of its mass: if marked wear, irregular shape or severely pitted surface is observed during the hull inspection, it is time to act. The general recommendation among professionals in the sector is to inspect and replace the shaft anodes at least once per nautical season, or every time the boat is taken ashore for maintenance. Not waiting for the anode to be completely consumed is the best preventive practice: an unprotected shaft can suffer irreversible damage that involves costly repairs in the dock.