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In article ,
says...
On Tue, 7 Dec 2004 14:44:15 -0500, "bob medico"
wrote:
I have a sailboat with a 1" stainless propellor shaft. The shaft is
supported outside by a rubber cutlass bearing in the hull (no strut). Inside
there is a short piece of hose with a stuffing box/ packing nut. When the
coupling is disconnected at the transmission the shaft will sag about 1/2".

Bob, I'm not totally sure you have a problem.

When disconnected from the engine/transmission, the shaft is supported
on two ends, one by the rubber 'Cutlass' bearing, and the other by a
(variably flexible) rubber 'hose' section to the "stuffing box'. Some
rubber hose sections are quite short and of rigid material, and the
shaft seems to hold position when disconnected. Others are more flexible
and 'sag' more.

The Cutlass bearings rarely wear out badly. I have one with 25 years and
thousands of hours on it. It probably has .025 sideplay but doesn't
complain. And that's a V8 powerboat running 2500 rpm, not a sailboat.

Grab the coupling on the shaft. Put a moderate amount of force on it
(say 5 pounds) in each of the up, down and sideways directions. How much
does it move? Is there a 'hard stop' feeling in each direction (may be
the shaft touching the inside of the "Shaft Log" or hull tube). If it
moves quite a bit, try to measure where the center of it's travel is.
Does that point right at the engine coupling?

There are two separate issues he

(1) Overall positional alignment of the engine coupling centerline with
the shaft centerline (In it's "center" position, whatever that is).

(2) The Angular alignment between the two couplings.

You must bring the two couplings together and THEN use "feeler gauges"
to determine if their angular alignment is right. "Right" means "they
meet squarely." If they meet squarely, the gap between the two coupling
halves will be zero (you can't get a thin ( maybe .002 in) shim in
anywhere around the periphery, or the SAME (You can put a feeler gauge
of (say .020) in all the way around and it is equally tight.

Settle the positional alignment issue first. Then check the angular
alignment.

Unless something drastic happened like worn or broken motor mounts, it's
unlikely that the positional alignment "went off" by 1/2" Thats a lot.

If that "rubber hose" section feels spongy at all, better replace it!
Greasing the stuffing box eventually deteriorates the rubber. You REALLY
don't want that hose section to fail!

Let us know if this makes sense, and what you see on your particular
boat and engine setup. I'd like to hear what you find out and finally
do!

(I'm current BoatLess In Africa and looking for an oldster to work
on...)

--
Regards, Terry King ...On the Mediterranean in Carthage