COLLARIN EJE 48 mm STD (ZN)

Function and technical context

The 48 mm shaft collar in standard size (STD) with zinc protection (ZN) is the support and sealing element that embraces the tail shaft as it passes through the hull or stern tube, maintaining the alignment of the propulsion shaft and reducing the vibration transmitted to the structure of the boat. It works within the power transmission system, at the interface between the interior of the hull and the marine environment, being one of the parts subjected to the greatest mechanical stress and galvanic corrosion. The integrated zinc coating or core performs a double function: it acts as a localized sacrificial anode that protects the stainless steel or bronze shaft against electrolytic corrosion, while the collar ensures correct axial support. If this part fails or loses its integrity, the shaft can shift longitudinally, cause abnormal vibrations in the propulsion line, accelerate wear of the stuffing box or horn, and compromise the maneuverability of the boat.

When to replace this part?

The most common symptoms of a deteriorated shaft collar are unusual vibrations noticeable in the hull or cockpit, metallic noise or hum in the shaft line at different speeds of rotation, and visible axial or radial play in the shaft when performing a dry inspection. The protective zinc should be inspected at least once a season or every time the boat is taken out of the water: when the zinc has consumed approximately 50% of its mass, replacement is immediate so as not to leave the shaft unprotected against galvanic corrosion. Replacing the collar preventatively during annual grounding maintenance is significantly more economical than facing an axle or horn repair for premature wear caused by poor clamping.

Compatibility table