COLLARIN EJE CORTO 19 mm. (ZN)

Function and technical context

The 19 mm short shaft collar made of zinc (ZN) is a galvanic protection component that is installed directly on the tail shaft of the vessel, acting as a sacrificial anode in the underwater transmission zone. Its main function is to concentrate electrolytic corrosion on itself, protecting the propulsion shaft, the horn, the stuffing box and other metallic elements of the transmission system against galvanic attack caused by continued immersion in salt or brackish water. By working as an active metal in the galvanic pair, zinc preferentially corrodes, preserving the structural integrity of the shaft and preventing it from suffering pitting or premature degradation that compromises the tightness and alignment of the drive assembly.

When to replace this part?

The clearest symptom that the zinc collar has reached its useful life is a visible reduction in its mass of more than 50%, presenting an irregular, porous surface or with completely consumed areas; at that point it has stopped offering effective protection to the axle. It is recommended to inspect and replace the zinc anodes of the shaft at least once per nautical season, or sooner if the boat remains in the water continuously in areas with high electrical conductivity or presence of parasitic currents in the pontoon. Renewing the collar preventively at the beginning of each campaign is the most common practice among nautical maintenance professionals to avoid costly damage to the shaft and bearings of the stern tube.

Compatibility table