ANODE SHAFT 55mm

Function and technical context

Shaft anodes are cathodic protection elements designed to be attached directly to the boat's propulsion shaft, acting as a sacrificial metal against galvanic corrosion that occurs when dissimilar metals are immersed in sea or brackish water. Its function is to oxidize in a controlled manner instead of the most valuable metal components of the propulsion system - such as the shaft itself, the propeller or the horn locks -, absorbing the galvanic current that would otherwise degrade these elements. This 55 mm inner diameter anode, reference CMX-55, is installed hugging the drive shaft using adjustment bolts, guaranteeing effective electrical contact and uniform protective coverage around the shaft. Without adequate cathodic protection, the shaft can suffer pitting, section reduction and, in advanced cases, structural failures that compromise navigation.

When to replace this part?

The clearest indicator that a shaft anode requires replacement is the loss of between 50% and 60% of its mass: when it has a very irregular surface, fractured or with the internal structure exposed, it has stopped protecting effectively. As a general rule, shaft anodes should be inspected every time the boat is taken out of the water and replaced at the beginning of each nautical season or sooner if wear is high, especially in areas with high electrical conductivity of the water or presence of eddy currents in the dock. Replacing the anode preventively before it is completely used up is the most economical measure to avoid serious damage to the shaft and propeller, the cost of which is much higher to repair or replace.