Page 36The Thrust Bearing

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The propeller shaft is pretty simple.

A straight shaft supported on two bearings with a propeller at one end.
The propeller blades should be equal and when spinning, there should be no vibration.
Rather like a flywheel.

And just like a flywheel, when spun, it should have momentum to spin for a while.
When the boat is out of the water, the bearings for the prop should enable the propeller
shaft to spin freely.

If it doesn’t. Engine power is being wasted.
Fix it.

There is another issue.

When the boat is cruising, the propeller is pushing the weight of the boat through the water.
Courtesy of Mr Newton’s “action and reaction”, the propeller shaft is pushed with equal force
into the boat.
The propeller shaft bearings are designed to allow freedom of rotational movement.
They are not designed to accommodate sideways load. This will create friction.

Fit a thrust bearing somewhere along the length of the propeller shaft.

Keep the friction down.

Let the propeller spin freely.