ANODE SHAFT 3-1/2

Function and technical context

The shaft anode is a sacrificial cathodic protection element that is installed directly on the tail shaft of the vessel, acting as an electrochemical barrier against galvanic corrosion in the marine environment. Its mission is to degrade in a controlled manner instead of the most valuable metal components, such as the propulsion shaft itself, the propeller or the tail bushings. This type of protection is especially critical in salty and brackish waters, where the potential difference between different metals—steel, bronze, aluminum—accelerates galvanic attack significantly. Without adequate cathodic protection, the shaft can suffer pitting, structural weakening and loss of section, compromising power transmission and the safety of the boat.

When to replace this part?

Shaft anodes should be inspected at least once a season, coinciding with annual beaching or bottom maintenance; The industry rule of thumb is to replace them when they have lost approximately 50% of their mass, since below that threshold the protection becomes insufficient. The most obvious symptoms of a depleted anode are the appearance of pits or reddish spots on the metal shaft and visible deterioration of the copper surface of the thru-hull. Replacing the CMC-14 anode preventively each season is the most economical measure to avoid replacing the propulsion shaft or propeller, the repair cost of which is much higher.

Compatibility