COLLAR SLIM Ø 50 mm (ZN)

Function and technical context

The 50mm slim zinc collar is a reduced profile sacrificial anode designed to be mounted on propulsion shafts, flying buttresses or submerged exhaust pipes on motorboats. It is part of the passive cathodic protection system, whose mission is to concentrate on itself the galvanic corrosion that would otherwise attack the base metal of the shaft or propeller. Thanks to its slim geometry – narrower than conventional collars – it is especially suitable for installations with reduced space between the shaft and the horn or buttress support. If this anode is depleted without being replaced, the shaft is left unprotected against electrolytic corrosion, which can cause pitting, loss of material and, in severe cases, blockage of the propulsion system.

When to replace this part?

Zinc anodes should be checked at least once a season and replaced when they have lost approximately 50% of their mass, have an irregular surface with deep cracks, or show a general whitish discoloration indicating depletion of active zinc. In saltwater environments with high galvanic activity—especially in ports with scattered electrical current—wear can occur within a few weeks, so monthly inspection is recommended during active navigation. Replacing the zinc collar preventatively at the beginning of each season is the most economical practice to avoid costly damage to the tail shaft or propeller.

Compatibility table