Cutless (not Cutlass!) Bearing Care

Posted by Frank Lanier at 09:31AM - Comments: (4)

Photo by Frank Lanier
Photo by Frank Lanier

This off-center shaft indicates that the cutless bearing is clearly worn. An obvious wiggle or audible thunk also suggests its time for a new bearing.

First, it’s time to clear up a little nomenclature debate. We are speaking here about the cutless bearing, the bearing for propeller shafts, which should not “cut” into your propeller shaft (although it surely can, if not maintained properly). We are not exploring the resting place for your trusty “cutlass,” the favorite tool of pirates. It is important to note that not everyone adheres to the time-honored distinction between “cutless” and “cutlass” in the Practical Sailor stylebook. In fact, many more entries for “cutlass bearing” than “cutless bearing” will pop-up in a Google search. Sorry Google, we stick to our guns on this one.

The cutless bearing supports the propeller shaft of your vessel while allowing it to turn freely without damage. Cutless bearings are typically made of brass with an interior rubber lining, which contains grooves running the length of the bearing. These grooves allow water to enter the cutless bearing to keep everything cool and lubricated while the shaft rotates within. Problems occur when the bearing lin- ing (and grooves) wear down, which both reduces the flow of cooling water and introduces looseness or play in the bearing.

To determine if your cutless bearing needs replacing, look for signs of wear or deterioration at both ends of the bearing. Rapid or unusual wear patterns (i.e. top wear on one end of the bearing, bottom wear on the other) are indications of significant shaft misalignment issues and should be addressed immediately.

Next, simply grab the prop or shaft and give it a couple of good, firm shakes to detect shaft looseness within the bearing. Slight movement (say 1/16” or so) is borderline, but if you can pro- duce visible shaft wiggle or an audible “thunk” when shaking the prop, the bearing is definitely due for replacement.

Comments (4)

Sorry Frank

A word trademarked by Johnson, i.e., Cutless(R), is not proper to use as a generic name for an item. e.g., "styrofoam coffee cups" or a "styrofoam cooler" are 1) not made by Dow-Corning and 2) not even the same material as Dow Corning Styrofoam (tm).

It should be referred to as a Johnson "Cutless(R) sleeve bearing" or a "Johnson Cutless(R) cutlass bearing," etc.

Practical Sailor(tm) magazine protects its trademark; please respect other ones as well.

Ken

Posted by: KMan | January 17, 2019 11:29 AM    Report this comment

tomiller

Impossible to answer. How many years should a tire last before it has to be replaced?

-k

Posted by: KMan | January 17, 2019 11:20 AM    Report this comment

Technically it is a Sleeve Bearing, not a Cutless (or cutlass). Cutless is a trade marked name (Like Coke or Kleenex) that has morphed into a pseudo-generic name.

Posted by: OS/2Dude | January 17, 2019 10:31 AM    Report this comment

How long should a cutlass bearing replacement last? I'm considering a boat which is supposed to have had it replaced in 2014. Yet a recent survey says that it needs to be replaced. Sign of misaligned prop shaft ? If so, what could be causing it?

Posted by: Tomiller | January 17, 2019 9:34 AM    Report this comment

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