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Project Log:  Wednesday, November 24, 2010

Lacking, at the moment, the time to immerse myself in one of the more involved jobs looming ahead, I decided to look into the disassembly--to the extent necessary--of the various components of the stern tube.  At a minimum, I needed to learn how the whole assembly went together and perform necessary inspection and maintenance; at the other end of the spectrum, I was considering revamping the inner end of the setup to incorporate a new thrust bearing and shaft connection system.  Ultimately, the decision how to proceed would hinge upon my findings and the current conditions.

Earlier in the unbuilding process, I'd removed the inner portion of the stuffing box, along with the old propeller shaft, leaving only the core components behind.  Since this area had until recently been hidden beneath the old fuel tank, as well as buried in varying amounts of debris, silt, and mud, I'd not yet spent any time inspecting the way the whole thing was put together. 

Before beginning, however, I decided to remove the rudder.  I knew this would be necessary later in order to install the propeller shaft, and now seemed as good a time as any to remove it; it would give me better access to the external part of the stern tube.

The rudder on this boat featured a nice practical workboat touch:  it was secured to the rudder shaft through a pair of square flanges, one secured to the shaft and the other to the rudder itself.  The flanges were held together with four bolts; removing the bolts would allow me to slide the shaft upwards enough to pull the rudder out. 


In practice, this worked as well as in theory.  Although the four bolts were caked in layers of bottom paint and slopped with the epoxy barrier coat that had been similarly slopped over the bottom of the boat, the nuts loosened easily.  I decided it wasn't worth trying to clean up the threads; I'd be replacing the bolts anyway.  The extra resistance of the thick paint eventually caused the nuts to seize up on their way off, to the point that continued wrenching simply snapped the soft bronze bolts.  All that mattered was removing the four bolts, not saving them.

In relatively short order, I'd removed the bolts, as well as a stop collar on the shaft that prevented it from moving upwards on its own.  Then, I could ease the shaft upwards as far as possible, giving me the space needed to pull the rudder up and out of its lower bearing point in the skeg.  This was by far the easiest rudder removal I'd had the pleasure to experience.  Reinstallation would be even easier.


With the rudder now out of the way, I covered the evil-looking corners of the square plate remaining on the rudder shaft with some cushioning so I wouldn't ram my head into it while working nearby.

Inside the boat, I checked out the connection of the metal stern tube, which ran from the deadwood to a point about 36" forward, where it was connected to the fixed portion of the old stuffing box with threads.  The stuffing box was in turn bolted to a small bulkhead, securing the whole works in place.  It was pretty clear that the stern tube, a metal cylinder threaded at each end, was threaded into a flange at the deadwood, which flange I imagined was part of the external housing.



Outside the boat was an external stern (Cutless) bearing housing, which was bolted to the deadwood.  From inside, I could see the other side of the bolts, or at least one of them; the second, bottom bolt was hidden beneath the stern tube assembly, and completely inaccessible to eyes, fingers, or tools:  the clearance between the stern tube and the hull in this area was less than a finger's thickness.

This effectively meant that at least to start, I wanted no part in any requirement to access that bolt.  So for the moment, this meant that I chose not to attempt to remove the external bearing housing, nor the stern tube itself.  Fortunately, there might be no need to do so either, but in any event I needed to feel my way along to determine the best course of action. 

There was no immediate reason why I needed to rebuild the whole system, nor any immediate reason why I might not leave well enough alone for once, but before closing this area off to access when I reinstalled a fuel tank over the space, I needed the setup squared away one way or the other.

For now, I focused on the external stern bearing.  Again, I was unclear exactly how this was configured.  There was a clamping bolt at the top side of the tube, which seemed logically to be intended to hold a normal-type Cutless bearing in place within the housing, aft of the internal stern tube and deadwood.  However, releasing and removing this bolt did not immediately release the protruding cylinder.

It was clear that within the protruding cylinder was the remains of an old Cutless bearing, severely worn and beyond salvage.  So to begin, I peeled out the rubber remains, which released easily by using a long screwdriver as a sort of chisel inside the tube itself.


After cleaning up the debris inside with some sandpaper and blowing the tube clean with air, I reinspected the inside as best as I could.  It looked like there was a seam inside, again seemingly a division between the internal stern tube and the external bearing.  I continued to surmise that eventually, the external part of the tube would come out of the bearing housing, or at least I hoped so; it didn't seem like a new bearing was supposed to go inside the existing tube, all the more so since there was no evidence of the typical brass shell of the old Cutless bearing remains that I'd removed.

I tentatively put a wrench on the cylinder, hoping to break it loose and turn it out, but to no avail, and I didn't put much pressure on the wrench lest I damage the tube.  Not knowing exactly how this whole setup was put together, and given the potential challenge of replacing all the components, I chose to proceed with plenty of caution.

For the moment, since I was about out of time, I satisfied myself by scraping and wire-brushing most of the paint off the bronze housing so I could better inspect it and decide how to proceed.  I thought careful application of heat to the housing would be next on the agenda, to try and release the bond between the two metal parts.

Then again, my theories might be completely incorrect, but in any event I'd find out soon enough.  One way or another, I'd need a new Cutless bearing at this end of the tube, whether it went inside the tube as existing, or not.  All would become clear in due course.

Total Time Today:  1.5 hours

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