ANODE SHAFT 4 CMC-15

Function and technical context

The shaft anode is a cathodic protection element designed to be installed directly on the boat's drive shaft, acting as a sacrificial metal that absorbs electrolytic corrosion before it affects the shaft, propeller or other submerged metal components. It works within the propulsion system, in the construction zone, where the combination of salt or brackish water, different metals and parasitic electrical currents generates a highly corrosive environment. Its presence is critical to preserve the structural integrity of the propulsion shaft: without active galvanic protection, the stainless steel or bronze alloy of the shaft can suffer pitting and loss of section that compromises power transmission and the safety of the vessel. The CMC-15 reference corresponds to a 4-inch shaft anode, a standard format widely used in recreational and fishing boats with propulsion shafts of that diameter.

When to replace this part?

Shaft anodes must be inspected at least once a season, usually at the annual beaching, and replaced when they have lost approximately 50% of their mass, since below that threshold they no longer offer effective galvanic protection. Symptoms of a depleted or missing anode manifest as visible pitting on the propeller shaft, erosion on the propeller surface, or accelerated corrosion on the shaft caps and horns. Changing the anode preventively at each grounding is the most economical measure to avoid replacing the entire shaft or propeller, repairs that can multiply by twenty the cost of a simple sacrificial anode.

Compatibility table

Note: There is no official list of compatible engines for this reference. Please check your boat shaft diameter before ordering.