What Are Cutlass Bearings? How Do They Work? What Are They Used For?

by whatsmind

Did you know that you should be performing a safety check on your boat at least once a year?

To a new boater, it may seem obvious that this check would include the engine, battery, propellors, and oil. What’s less obvious, however, is that you also need to inspect your boat’s cutlass bearings.

What is a cutlass bearing, you ask? Here, we break down what cutlass bearings do and some basic cutlass bearings tips to keep your vessel in tip-top shape.

What is a Cutlass Bearing?

Cutlass bearings are tubes of nitrile rubber encased by metal. On the inside of the nitrile, there are grooves all the way around that run down the length of the cutlass bearing.

The cutlass bearing goes around the propellor shaft to provide stability and lubrication to the propellor shaft while it rotates. Since the grooves in the nitrile allow water to pass through the bearing and around the propellor shaft, it also helps cool the propellor shaft in addition to providing lubrication.

These grooves also wash away any sediment or abrasives that might otherwise build up inside the bearing and harm the propellor shaft.

Cutlass Bearing Types

Propellor shaft bearings used to be made from Lignum Vitae, one of the densest woods on Earth. However, this wood is notoriously difficult to work with, so when it was discovered that nitrile would work just as well, the industry switched over to rubber cutlass bearings instead of wood.

Cutlass bearings are encased in a metal tube. These tubes are made from bronze, stainless steel, or other metals.

Depending on the style of the boat, a P-bracket or the stern shaft may encase the cutlass bearing. In either case, plastic or metal screws hold the cutlass bearing in place.

When to Replace Cutlass Bearings

You should check cutlass bearings every time you pull your boat out of the water for inspection.

Hold the propellor and gently try to shake it. If there’s no give, the cutlass bearing is still working well. If there’s room for the propeller shaft to move around inside the cutlass bearing, though, you need to replace the bearing.

You can sometimes also tell when a cutlass bearing needs replacing while driving the boat. You may begin to feel a vibration, particularly at high speeds, which indicates that the propellor shaft has room to move around within the cutlass bearing.

Cutlass bearings are not difficult to replace. Simply remove the propellor from the propellor shaft, slide the cutlass bearing out of the metal tube, and replace it with a new cutlass bearing.

When cutlass bearings are encased in the shaft log, they may be harder to access. The same basic principles apply to the replacement process, but you first need to remove the entire shaft to access the cutlass bearing.

If left unchecked, a worn cutlass bearing can cause damage to your engine mounts or propellor shaft.

You Need High-Quality Cutlass Bearings

Now you know the basics of cutlass bearings, their uses, and how to properly maintain them. Check this vital piece of your boat regularly, and you can rest easy that your boat is safe and seaworthy.

Looking for other news related to health and leisure? Check out the articles in the Sports and Lifestyle sections of our site for more!
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