2 1/2 SHAFT COLLAR

Function and technical context

The 2 1/2" shaft collar is a sealing and retaining component that works directly on the boat's drive shaft, acting as a holding and guiding element between the shaft and the stern tube or stern bearing. Its main function within the drive system is to maintain correct alignment of the drive shaft, prevent unwanted axial displacement and ensure watertightness in the hull penetration zone. Without this element in perfect condition, the shaft can suffer excessive vibration, premature wear of the packing or stuffing box, and in extreme cases the integrity of the hull seal may be compromised, with the risk of water entering the bilge.

When to replace this part?

The most common symptoms of wear on a shaft collar include abnormal vibrations transmitted to the hull during navigation, noticeable lateral play in the propeller shaft when moved manually with the engine stopped, or visible wear on the contact surface of the collar. It is recommended to inspect this component during each seasonal maintenance, especially after a grounding or impact with a submerged object, since bending forces can deform or displace the collar. Replacing it preventively when any looseness is detected prevents further damage to the shaft, horn and sealing system, repairs that are considerably more expensive if carried out in an emergency stranding.

Compatibility table