COLLAR SHAFT 48mm.

Function and technical context

The 48mm axle collar is a retaining and centering element that works directly on the drive shaft in the boat's axle line. Its mission is to maintain the axial position of the propeller shaft, avoiding longitudinal displacements that would compromise the alignment between the propeller and the stern tube bearing. When integrated into the transmission system, it acts as a mechanical reference that absorbs the thrust generated by the resistance of the water on the propeller and transmits them in a controlled manner to the structure of the boat. A worn, broken or poorly adjusted collar causes excessive vibration, loss of propulsive efficiency and, in advanced cases, can cause damage to the horn, the stuffing box or even the shaft itself, generating costly interventions in the slipway.

When to replace this part?

The most common symptoms of deterioration in a shaft collar are abnormal vibrations transmitted to the hull at certain revolutions, noticeable play in the shaft when moving it manually with the boat dry, and the appearance of metallic noises in the transmission line during navigation. It is recommended to inspect the collar at each seasonal landing and replace it if there is any sign of looseness, pronounced corrosion or visible deformation. Replacing it preventively during annual maintenance avoids navigation breakdowns that require towing and emergency repairs at a much higher cost.