ANODE SHAFT 25 mm.

Function and technical context

The 25 mm shaft anode is part of the boat's cathodic protection system, acting as a sacrificial element that preferentially corrodes to protect the tail shaft and nearby metal components—propeller, horn, buttress—against galvanic corrosion produced by continued immersion in salt or brackish water. Its direct installation on the drive shaft guarantees a protection zone located in one of the most exposed and critical points of the drive train. Without effective cathodic protection on the shaft, galvanic corrosion can cause pitting, material loss and, in advanced cases, structural weakening of the shaft itself, which compromises navigational safety and can lead to costly drive train breakdowns.

When to replace this shaft anode?

The clearest sign that the anode has fulfilled its function is the visible reduction in its mass: when the anode has lost approximately half of its volume or has an irregular and severely eroded surface, it should be replaced immediately. The usual practice in nautical maintenance is to inspect and replace the shaft anodes at least once a season, or at each maintenance dock, without waiting for them to be completely consumed. Replacing the anode preventively is the most economical measure to avoid damage to the tail shaft, propeller and horn bearings, the repair of which is considerably more expensive than the cost of the anode itself.