ANODE SHAFT 1-3/4`` ALUMINUM

Function and technical context

Shaft anodes are cathodic protection elements located directly on the boat's drive shaft, between the hull and the propeller. Its function is to act as a sacrificial metal, absorbing galvanic corrosion that would otherwise attack much more expensive structural components such as the axle itself, the horn, the propeller or the bronze fittings. The CMX-8A anode is made of aluminum alloy, a material especially suitable for navigation in salty and brackish waters, where the electrochemical activity is more aggressive. Its inner diameter of 1-3/4 inches determines its direct mounting on shafts of that size, guaranteeing correct electrical contact and uniform protection around the shaft.

When to replace this part?

The clearest sign that the shaft anode has reached the end of its useful life is the visible reduction in its mass: when it has lost approximately half of its volume, it must be replaced without delay, as its protection capacity is compromised. The inspection of the anodes should be carried out at least once a season, coinciding with the annual beaching, although in areas of high electrical conductivity or with intense eddy currents an intermediate inspection may be necessary. Replacing the anode preventively is the most economical maintenance measure possible to avoid corrosion of the shaft and other elements of the propulsion line, the repair of which can cost several hundred euros.