John,

Yes, I was contracted to repair the strut bedding when the boat got run
with a damaged blade. That boat did not have the couple you describe
between the hydralic motor and the prop shaft. There was also no
conventional stuffing box. The prop shaft is enclosed in the stern tube
from the after end of the strut into the hydralic motor. The motor is
actually attached tot he stern tube and is supported by both that and a
torque brace.

After we got all of the other stuff fixed, the boat still would not make
more than 4 knots and the engine was not loading. It back like a mad
man. So the owner got another set of blades for the other rotation and
shifted the pump to astern for ahead and now makes hull speed just fine.
When I talked to him last he was trying to find someone that knew how
to overhaul the pump and motor. When I see him next, I will ask him.

A chain coupling in a drive shaft is rare and not a proper application.
There is no way to put an axial load bearing (thrust) inside the stern
tube, so it must be in the hydraulic motor. That is part of why the
plastic washer is both installed and torn up. I suspect the washer is
required to keep the coupling halves from wearing on each other.

It is, however, not costing you horsepower. Bearings going bad can
cause vibration and failures, but if they eat horsepower they burn up
real fast. I suspect that if you are short on boat speed as you seem to
say farther down the thread, you have hydraulic drive problems just like
the Scampi I know had (may still).

I would see about getting both the pump and motor looked at before you
invest much effort in other paths.

Good Luck

Matt Colie - See Prior Sig

john m. wrote:

"Steve" wrote in message ...

To me, this is a bit confusing??

Does your boat have an inboard engine with a propellor shaft?? or are you
talking about an Outboard motor or Out drive??

A properly installed marine engine will have the thrust bearing in the
reduction/reverse gear. If it is an OB or Out Drive, the thrust bearing is
inside the lower unit. I've never heard of a thrust bearing at the
propellor. There should only be a water lubricated cutlass bearing.

Please provide more information on what you have, engine/rev. gear, etc. and
maybe we can figure a solution.

Steve
s/v Good Intentions


Here is a link that shows a diagram of the boat
http://home.worldonline.dk/sejler/scampi/scampi.htm
This boat has an hydraulic drive system. The brace that you see in
front of the impeller is where the bearing should be ( I think) It
looks like a very strong support made out of metal and imbedded in the
fiberglass.