ANODE SHAFT 35 MM. ALUMINUM

Function and technical context

Shaft anodes are cathodic protection elements designed to be electrochemically sacrificed in place of noble metal parts of the vessel, such as the propulsion shaft, propeller or seal. This aluminum anode for 35 mm shaft is installed directly on the tail shaft, acting as an active barrier against galvanic corrosion that occurs when different metals coexist submerged in salt or brackish water. The aluminum alloy makes it especially effective in marine waters of medium-high salinity, offering longer-lasting protection than zinc in certain environments and being environmentally friendly as it does not contain mercury or cadmium. Without adequate cathodic protection, the stainless steel or bronze shaft would be exposed to accelerated deterioration that compromises the structural integrity of the transmission line and can lead to vibrations, loss of performance or even shaft breakage while underway.

When to replace this part?

The clearest indicator that the shaft anode has exhausted its useful life is the visible mass loss: when the anode has consumed between 50% and 70% of its volume, it must be replaced without delay, since below this threshold the cathodic protection is insufficient. Inspection and replacement is recommended at least once per nautical season, coinciding with the annual beaching, although in areas of high electrolyte activity or very conductive waters it may be necessary to check it every 6 months. Replacing the anode preventively is the most economical measure to avoid corrosion of the shaft, propeller and mechanical seals, the repair or replacement of which involves a much higher cost.