Its Proper Name is a Cutless Bearing - Here's Why

I continue to hear people use the wrong words to describe something nautical. In this case, I refer to whether the bearing that cradles a propeller shaft is called a “cutless” or “cutlass” bearing. Most direct drive boats have one or two of these bearings.

Several years ago, I reached out to a number of professionals in the marine industry, who could neither agree or offer definitive proof one way or the other. But eventually I found the true origin and history of the term. And its roots are not even nautical.

After speaking with Dave Gerr, author of The Propeller Book, I called Mike Schonauer, who was at the time VP of Sales & Marketing for Duramax Marine of Hiram, Ohio. Duramax is a pioneer in marine bearings.

Mike was happy to explain the history of the bearing, in which his company is part. In the 1920s, Charles Sherwood, an engineer responsible for maintaining vertical lift water pumps used in mining operations. The traditional bearing material used in these pumps was lignum vitae, the world’s heaviest and densest hardwood. Given the abrasive nature of this water, sludge, and mud pump application, the hardwood bearings needed frequent replacement, a regular chore for Mr. Sherwood.

Preparing to again replace a pump’s bearings, he found they were out of lignum vitae. A clever engineer, he searched his shop for alternatives and found a sheet of rubber. Having nothing to lose, he decided to cut some temporary bearings for the pump from the rubber material, getting the pump back online. He kept an eye on the pump’s operation over the next several weeks while he restocked his hardwood supply.

He was intrigued to find the pump shaft was doing nicely with the rubber bearings, much more so than with lignum vitae bearings. He noticed the shaft was not being grooved or worn by the rubber bearing, even in such an abrasive environment. The rubber bearing had, in fact, “cut less” into the shaft surface than the hardwood bearings. A year or two later, the bearing was patented by Charles Sherwood in conjunction with Lucian Q. Moffit of Akron, Ohio, who coined the term “cutless” bearing.

Mr. Moffit eventually sold out to B.F. Goodrich, where in the 1950s, the bearing division came up with the marketing idea of stamping a sword symbol on its cutless bearing products as a form of branding. The confusion of the cutless bearing with the symbol of the cutlass was born.

Johnson Rubber, also started in the 1920s, in which Duramax Marine was a division, made its own version of bearings and stuffing boxes. Duramax Marine became its own corporate entity in later years, and eventually purchased the bearing division from B.F. Goodrich.

Today Duramax Marine makes all sorts of bearings, cutless bearings included, for hydroelectric turbines, agricultural vertical pumps, and many other applications outside of strictly marine use. The design of the cutless bearing allows it to handle much greater loads than roller bearings, due to the lubrication features of the bearing design.

And to further distinguish the bewilderment between a cutless bearing and the cutlass sword, Mike Schonauer offers that today the proper term for the bearing is a “water lubricated, hydrodynamic standard rubber sleeve bearing.”

You learn something every day!


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