COLLARIN EJE 2" STD (ZN)

Function and technical context

The standard 2-inch zinc-protected shaft collar is an essential component within the drive and propulsion system of tailshaft boats. Its main function is to anchor and position the propulsion shaft, avoiding unwanted axial displacements that would compromise the alignment between the engine and propeller. By incorporating integrated sacrificial zinc, it simultaneously acts as a galvanic protection element, retarding the electrochemical corrosion that affects the shaft in saline or mixed marine environments. A deteriorated collar or one without active zinc causes abnormal vibrations in the shaft, accelerated wear of the stern tube bearing and, in extreme cases, can lead to loss of tightness of the stuffing box or structural damage to the propulsion shaft itself.

When to replace this part?

The most common symptoms of a bad shaft collar include noticeable vibrations in the deck or gas control, metallic noises coming from the shaft area while underway, and visible corrosion or completely consumed zinc when inspecting the shaft under the hull. It is recommended to check the condition of the zinc in the collar at least once per nautical season—or every 200-300 hours of navigation in areas of high salinity—and replace the assembly when the zinc has lost more than 50% of its mass. Preventatively replacing the collar during the annual beaching is a low-cost measure that prevents costly transmission system breakdowns when the boat is in the water.

Compatibility table