COLLARIN EJE 90 mm STD (ZN)

Function and technical context

The standard 90 mm shaft collar with zinc protection is the sealing and supporting element that embraces the tail shaft as it passes through the hull, acting as a dynamic seal between the marine environment and the interior of the boat. It works within the transmission system, specifically in the horn or stuffing box area, where the propeller shaft passes through the hull skin to connect the engine with the propeller. Its function is twofold: on the one hand, it prevents water from entering the interior of the helmet; On the other hand, it keeps the axis correctly centered and aligned, reducing vibrations transmitted to the hull during navigation. The integrated zinc component acts as a localized sacrificial anode, protecting the shaft and adjacent metal parts from galvanic corrosion, a critical factor in installations with stainless steel or bronze shafts exposed to salt or brackish water. If this collar fails, wears out or loses the correct tightening, the consequences can range from progressive water seepage to accelerated corrosion of the shaft, with the consequent risk of structural failure during navigation.

When to replace this part?

The most common symptoms that indicate that the shaft collar needs replacement are: visible dripping or continuous leakage around the shaft in the stern tube chamber, unusual vibration or clunking noise from the stuffing box area, visible zinc wear (anode reduced to less than 50% of its volume), or scuff marks on the shaft. It is recommended to inspect the collar during each seasonal maintenance - at least once a year - and replace it whenever looseness, cracks or erosion of the zinc material are noticed. Performing the change preventively before launching the boat at the beginning of the season avoids costly repairs in the dock or compromised situations on the high seas.

Compatibility table