Why You Should Care About Your Boat’s Cutlass Bearing
The cutlass bearing is an internal rubber sleeve pressed into the strut supporting the propeller shaft. Depending on your boat design, you may have one, two, or three struts per shaft. This is determined by the size of the propeller and the length of the shaft. These additional struts help keep the shaft straight and true, and every strut must be protected with a cutlass bearing.
That’s a lot of words, but do you care about the cutlass bearing yet? This nautical cutlass is usually made of a bronze or synthetic outer shell surrounding an inner rubber-like sleeve with grooves inside. The linear grooves are a part of the lubricating and cooling design. These grooves allow water flow around the spinning shaft. This prevents the fast-rotating propeller shaft from overheating and scoring the stainless steel shaft itself.
When you attend a marine survey before purchasing your boat, pay attention to what the surveyor looks for. Once the boat is hauled, the surveyor will squat, seeming to bench-press the propeller and shaft. They will attempt to lift the prop, sometimes even grabbing the rudder to wiggle it. If the boat is larger with a heavier propeller and shaft, the surveyor may use a different technique to learn the same information. You may see them grab a wooden block and a long board to serve as a lever. Either method will determine if the cutlass bearing has significant wear.
