ANODE SHAFT 4

Function and technical context

Shaft anodes are cathodic protection elements designed to be attached directly to the tail shaft of the vessel, acting as a sacrificial mass that concentrates galvanic corrosion on itself. Its function is to protect the propeller shaft—normally made of stainless steel or naval bronze—against the electrochemical attack produced by the potential difference between different metals submerged in salt or brackish water. Without properly sized cathodic protection, the shaft can suffer from pitting, cavitation corrosion and section loss that compromise both the structural integrity of the shaft and the sealing of the tube and the stability of the propeller. The CMX-17 anode is part of the underwater drive train cathodic protection system and works in coordination with the propeller, rudder and hull anodes to ensure the integrity of all submerged metal components.

When to replace this part?

The unequivocal symptom that the shaft anode has reached its useful life is the visible reduction in its mass: when the anode has lost approximately 50% of its volume it must be replaced immediately, since below that threshold it stops offering effective protection. The recommended inspection and replacement is annual, coinciding with the seasonal stranding, although in areas with high salinity or waters with high electrical conductivity it may be necessary to review it every six months. Replacing the shaft anode preventively at each grounding is the most economical measure to avoid replacing the drive shaft, the stern tube or the propeller, repairs that cost much more.

Compatibility table