ANODO HELICE TWIN DISC-BCS Ø68 (ZN)

Function and technical context

The Ø68mm Twin Disc-BCS propeller anode in zinc acts as a sacrificial cathodic protector on the propeller and driveshaft assembly, absorbing galvanic corrosion that would otherwise attack higher value metal components such as the propeller hub, shaft and tail fittings. This element works within the propulsion system, specifically in the submerged area where the propeller is in continuous contact with salt or brackish water, environments in which electrochemical corrosion is especially aggressive. Zinc, due to its more negative electrochemical potential, preferentially oxidizes before the aluminum or bronze of adjacent components, constituting the first line of defense against degradation of the propulsion train. If this anode is completely consumed without being replaced, the galvanic attack moves to the propeller hub, shaft and bushings, causing costly structural damage and possible loss of boat steering.

When to replace this part?

The clearest symptom that the propeller anode needs to be replaced is a visible reduction in its mass: when the anode has lost approximately 50% of its volume it must be replaced without delay, since its protective capacity decreases exponentially from that point on. In waters with high conductivity (marines, estuaries or ports with erratic currents), wear can occur in a single season, so annual inspection and replacement, coinciding with the seasonal beaching, is the practice recommended by propulsion system manufacturers. Preventatively replacing the anode is significantly more economical than repairing or replacing a propeller shaft or hub damaged by uncontrolled galvanic corrosion.