Bad news today when I went to replace the log hose and gland packing. The inboard end of the shaft log is badly dezincified and there's barely enough sound material left to clamp the hose back on and stop the leak. Bit of a bummer, but better to find out this way on the mooring than undergo sinking out on the oggin. I'm pretty comfortable with cutting the glass away and epoxing a new tube in place. It's the alignment that's got me a bit worried. Anyone here with helpful advice?
Cheers, Graeme
I've not owned a boat with a hose mounted gland, but I was under the impression that the " floating gland " allowed for a certain amount of misalignment ?
Select to expand quotewoko said..
I've not owned a boat with a hose mounted gland, but I was under the impression that the " floating gland " allowed for a certain amount of misalignment ?
Bit of a misunderstanding there: I'm talking about the tube that contains the cutless bearing. It's solidly glassed into the hull.
I would use a dummy shaft or prop shaft as an alignment jig.
Basically glass the new log in whilst it's on the shaft and fitted into the gear box coupling.
Some couplings like the polyflex you could remove the flexible piece to eliminate errors from flexing,, or you could build an alignment support to hold shaft alignment before the log is removed, then remove the old log, fit the new log on the shaft and slide the whole lot into the boat, sliding the shaft through the alignment support and into the gear box coupling . The support could be something like a piece of wood with a hole in it the size of the shaft glued to a frame or stringer.
It's important to set up the alignment support on a shaft before you remove the old log.
It's a lot simpler if you have an external p-bracket bearing to hold the dummy shaft alignment.
The stern tube replacement went surprisingly well. The copper tube came out using a DIY puller consisting of 1/2" threaded rod, nuts, suitably sized washers and 40 cm of 1 5/8" gal pipe (the tube is 38.5 cm long) for the tube to slide into. The f/g bore was in pretty good nick and all it needed was a clean up with a 40mm flapper wheel on an extension shaft. The new tube then went in easily with epoxy applied to both the tube OD and the f/g bore, with firm hand pressure. There was no radial play, so hopefully minimal change in aligment (next job on the list).
I'm intrigued as to the cause - perhaps 50 years of the slightly different corrosion potential between the ss shaft and the copper? Work hardening of the copper from vibration after thousands of hours of engine time?
Anyone with an old boat with a copper stern tube (and/or rudder tube - a guy on the FB ompass group posted a pic of his similary depleted rudder tube) might want to consider this job on their next slip. Certainly a sensible job if you're doing the cutless. If your prop and coupling come off without too much grief, the tube replacement is probably under a day's work.
Anyone wanting more gory details and pix, DM me.
Cheers, Graeme
