SHAFT COUPLING TO PROP DETAILS, PART 2

[bob mitchell]

Clyde caught this cutlass bearing intake in one of the photos of the deadwood repair, and emailed me back.

 

Bob,

 

Very interesting pictures—you should keep the camera.  I have isolated a detail in one of them that you should take an interest in.  The two red arrows point to the remains of a plastic tube that needs replacing after you finish fiberglassing the boat.  A picture is worth a thousand words, so I’ll draw a picture of what it should be.  This tube is the water intake that provides cooling water for both the Cutlass Bearing (stern tube bearing that hold the shaft centered in the alley) and the stuffing box.  You will note that the tube (actually two tubes, one on each side) is more or less flush to the inside of the alley (shaft or stern tube).  The outside end is cut at a 45 degree angle so the opening faces forward.  The boat moving ahead forces water into the alley under a bit of pressure; a little goes forward a drop at a time through the stuffing box.  The stuffing box should not completely stop the water “flow.”  If the stuffing box is too tight because of an effort to stop the dripping, it will squeeze the flax packing out of shape, and apply a lot of wearing pressure on the shaft.  It’s not a pretty sight to see a shaft worm into uselessness after a season of stupidity.  The water that doesn’t go forward is pressured out through the grooves in the splined rubber liner of the Cutlass bearing. This water both lubricates and cools the shaft and the bearing.   With that, the drawing may be understandable.  If you have questions don’t be slow in asking.

 

Hope this is clear and helpful.  The intakes are necessary for the longevity of your shaft.

 

Peace,

 

    Clyde

 The diagram above shows two different alternatives, one in the red box and one on other side. Thanks for the great diagram, Captain Clyde!