ANODE SHAFT 75 mm.

Function and technical context

Shaft anodes are essential components within a vessel's cathodic protection system, acting as an electrochemical sacrifice to preserve the tail shaft and adjacent metallic elements against galvanic corrosion produced by contact with salt or brackish water. This 75 mm zinc anode is mounted directly on the propulsion shaft, interposing itself between the noble metal of the shaft and the corrosive aqueous medium, so that it is it that oxidizes and is consumed instead of the shaft. Without adequate cathodic protection, the propulsion shaft can suffer from pitting, sectional thinning and brittleness that compromises the structural integrity of the drive, putting the safety of the vessel at risk and leading to costly drive train breakdowns.

When to replace this part?

The clearest sign that the shaft anode needs to be replaced is loss of more than 50% of its mass or the presence of an uneven, porous, badly worn surface visible during grounding or dry holding. Shaft anodes must be inspected at least once a season and completely replaced at each annual beaching, regardless of the degree of apparent consumption, since a depleted anode leaves the shaft completely unprotected against galvanic corrosion. Replacing the anode preventively at each seasonal tune-up is the most economical measure to avoid replacing the drive shaft, a significantly more expensive repair.