Jim
It's a little hard to imagine this from the words, ( I'm a scribble it on
the floor person ... ) but I can't see why a coupling would not work. I
think you have a rudder on a shaft which has a lower ( skeg ) bearing and an
upper ( stuffing box ) bearing. The steering quadrant is above the stuffing
box, and there will be some shaft free above the quadrant. So the shaft is
stiff enough to take the steering forces on the overhung section above the
stuffing box.. You need the upper bearing because the extended shaft is not
stiff enough to take the forces from the tiller as an overhung load.

If you mount one half of a standard engineering type split coupling to the
protruding shaft, and the other half of the coupling has the bottom of the
"extension " shaft --- the top end of the "extension " shaft goes through
the upper bearing. And the tiller connects somehow to the extension
shaft - I'm assuming above the upper bearing.

I'm assuming this is all done with standard shafting, with torque
transmitted by keys in keyways, and the couplings held in place by locking
screws.

So to remove everything, you disconnect the tiller and it's attachment,
loosen the collar on the upper bearing, ( the one which stops the shaft from
riding up, because the keyway locking screws won't ) loosen the locking
screws on the upper half coupling key, and the shaft just pulls straight up.
Then loosen the locking screws on the lower half coupling, and pull the
coupling off the lower shaft. I can't comment on how the rest of the stuff
goes, but it should be along the same lines.

I've left out the bits about everything being corroded together, dropping
keys and screws into the bilges, and getting nickel anti-seize all over
everything ... but it's a boat, right?

I would probably use a split coupling if I had the space, because if the
coupling halves are stuck to their respective shafts, you can use a bearing
puller to help remove the coupling. You could use a one-off split coupling,
but it's going to be dearer because you will have to design it and have it
machined. But if nicely designed the keys will be captive in both the
coupling and shafting, so there is no need for locking collar on the upper
bearing........

Now someone who really knows what they are doing can tell me where I'm
wrong. The above is how I'd do it industrially, it's not necessarily going
to translate to the boat situation.

Regards
David

"jimthom" wrote in message
om...
Thank you for your views. I will have a steering quardrant for
hydraulic steering (wheel inside) below the coupling (with a shunt
valve) and tiller in the cockpit. The lower skeg bearing will prevent
the rudderpost from exiting the coupling and the bottom of the hull. I
can't use a flange for the coupling since I will need to cut it off to
remove the rudder post from the stuffing box, but you have givin me
some food for thought - Thank You
jimthom


"Steve" wrote in message
...
"jimthom" wrote in message
om...
splined sleeve), or is there another solution to the problem of
removing a very long rudder post? (rudder stock is solid 1 1/4" ss).


You don't say if you are wheel or tiller steering.. A two piece rudder
would
tend loosen up from constant torsion with a tiller or quadrant above the
shaft coupling.

A coupling would work but in addtion to the splines or key, your
coupling
should be split so that several bolt will apply camping force around the
shaft.

Also there should be a bolt going through both the upper and lower so
the
weight of the rudder doesn't pull it out of the coupling. This can
accomplished by the clamping bolts passing through a notches in the side
of
the shaft.