Replacing the parts that make it Go.

 


All this work started out to be nothing more than my Dad and I attempting to replace the old packing in the stuffing box.

When the stuffing nut was first backed off, it was very apparent that there was going to be no room to get a tool into the old packing to remove it. We tried seperating the shaft from the coupling to slide the shaft out, but that effort cost us nearly a week, with no luck. We finally got to the point where cutting the shaft was the only option. A sawz-all, four hard hours, and a dozen carbide blades later, we had the shaft cut.

We had to pull the rudder to get it the shaft all the way out. Good thing she's on a slope and I could dig the ground out from under it.

Now with the shaft out we had to remove the old coupling from the engine. The old bolts had rusted a great deal and were difficult to remove. With all that done we were ready to install the new parts. A local machine shop built a new shaft and coupling assembly, and provided a new cutlass bearing.

The cutlass bearing was removed by cutting two slots an 1/8" apart through the nitrile and brass bearing. A hacksaw blade was used to do this. A great deal of care had to be taken not to cut through the bearing into the strut. Due to flex in the saw blade, the ends of the cut reached the strut first, leaving material in the middle. A punch was used to roll the thin strip up, much like the lid on a sardine can. With the strip removed the bearing came out easily. Sorry no pics for this process.


Shaft Coupling A split coupling, with set screw, replaced the old solid coupling. Care had to be taken, when installing, to make sure the key was positioned correctly. A dimple was drilled into the shaft for the set screw. This helped to line up shaft and coupling into their proper position.

The shaft and coupling are milled as one piece, this makes sure the shaft and face of the coupling, are perpendicular. If this is not done, it'll wabble like a dog's tail...

Coupling_stuffingBox1 New stuffing box and "rubber thing". A heavy duty set of clamps are best. Note the screw area of the clamps are opposed.

Double clamp !

ScrewSrew_in_strut After the cutlass bearing was removed, a holes were drilled through the strut, middle way along its length.
Taping Strut The holes were tapped to receive set screws.
Cutlass_Installation_jig A 3 foot, 1/2" threaded rod with plenty of washers was used as a come-along. Using a wrench to turn the single nut, slowly moves the bearing into place.

Not seen here are two nuts on the opposite side. The two nuts are locked to help hold the rod from turning. You'll need a couple of wrenches to keep pressure on the lock nuts.

The cutlass bearing is pressed into placed very, very carefully at first. It's very important to get the line up right so as not to distort the strut and jamb the bearing. Once enough of the bearing is in, it will line up by itself. A little grease on the threaded rod, at the nut helps, but be careful to keep it off the bearing. There's a lot of pressure on the washers, use plenty or they'll cup and jamb the nut.

Cutlass_in_strut From this picture you can see how thin the material is on the strut surrounding the cutlass bearing. At its thickest I'm guessing it was 3/16" - 1/4" thick. This is why so much care was taken to remove the old cutlass and not cut into the strut. The set screws are installed at this point. Don't over tighten or you'll mash the cutlass bearing.
RubberThing Here's a look at the thickness of the new rubber thing. The original one was only a quarter the thickness and badly cracking. The rubber coupling connects the stuffing box to the stern tube on the inside of the boat. This provides a flexible connect between the shaft and boat.
Sterntube Stern Tube.
RubberThing_install Due to its size and thickness, this coupling had to be pressed into place. The same threaded rod used for the cutlass bearing is used here. A wooden "washer" was made to add diameter on this end of the rod. Not shown is a wooden, wedge shaped piece used on the outside of the stern tube. It helped keep the washer perpendicular to the shaft. Not a great deal of pressure is needed here, however the rubber had a difficult time going on straight. No grease was used on the rubber to help it go on. The inner edge was slightly tappered with a knife instead.

Be very careful in cutting the rubber coupling to the correct length. I found its length shortened after it was pressed on. Fortunately, I had extra.

Shaft Exits Stern Tube Before bolting anything together, test the fit of the shaft in the stern tube. You should have a nice even amount of room around the shaft. If its too close, any movement of the strut, boat, or engine could cause the shaft to wear the stern tube.
Stuffing Box installed Here it is, the almost finished job. All that is left to do is put the screw on. After the boat is in the water for a week, the connection at the coupling will be re-aligned. There is a tendency for the boats shape to change after it is off the keel. The change is enough to cause the gap between the coupling to to change as well.

 


William R Sindt, Last updated: Apr. 4, 2002