ANODE SHAFT 50 mm.

Function and technical context

The shaft anode is a sacrificial element that is part of the boat's cathodic protection system, installed directly above the tail shaft to neutralize galvanic corrosion that occurs when submerged metals come into contact with salt or brackish water. Its mechanism of action consists of oxidizing preferably with respect to the steel or bronze of the shaft, thus protecting higher-cost components such as the shaft itself, the flying buttress, the propeller and the caps of the propulsion system. Without adequate cathodic protection on the shaft, electrolysis acts silently and continuously, causing pitting, loss of material and, in advanced cases, structural weakening of the shaft that can compromise the integrity of the transmission and the safety of the boat. The CMC-50 model is designed for 50 mm diameter shafts, which makes it suitable for medium-large boats with propulsion shaft lines of that size.

When to replace this part?

The clearest sign that the shaft anode needs replacement is a visible reduction in its mass: when it has lost approximately 50% of its initial volume, it no longer offers sufficient protection and must be replaced immediately. Shaft anodes should be inspected at least once a season, preferably during the annual beaching, and replaced before launching the boat if they show significant wear, uneven surface or cracks. Replacing the CMC-50 anode preventively at each grounding is the most economical practice to avoid corrosion damage to the tail shaft, the repair or replacement of which involves grounding, disassembly and machining costs much higher than the price of the anode itself.