Cutless Bearing

A water-lubricated bearing that supports a vessel’s propeller shaft near its passage outside the hull.

The bearing has longitudinal water channels and a resilient or composite bearing surface within a rigid shell. Water flowing through the grooves lubricates and cools the shaft as it rotates, and the unit is commonly fitted in a stern tube or strut.

“Cutless” is the established spelling derived from an early trade name, although “cutlass bearing” is widely heard. Wear, poor alignment, inadequate water flow, debris and shaft damage can cause vibration or accelerated deterioration; the permitted clearance depends on the installation and manufacturer’s specification.