what happens in reverse?

"john m." wrote in message
m...
Thank you guys for the replies.
There is one problem. The propeller shaft has a roller chain coupling
that connects it to the hydraulic drive. I think that this type of
coupling does not take any axial load too well. The only place left to
take the axial load is the strut in front of the impeller. When I look
at the plastic washer I can see where the axial load eats away at the
plastic thrust washer. That is why I was thinking to replace the
plastic thrust washer with something more robust.

barry lawson says:

what happens in reverse?

Heehee..... I hadn't even thought about that. Good question.

;-)

Opps! Been there done that!

Once had the shaft spin out of the coupling while in reverse.. It even
cleared the packing box but jammed against the rudder..

Took on some water until I could warp myself back into the dock and drive a
plug into the packing box..

Later had a diver push the shaft back in, knocking the plug out.

Since then I have always had a through bolt or pin in additions to the set
scews.


--
My opinion and experience. FWIW

Steve
s/v Good Intentions

"barry lawson" wrote in message . au...
what happens in reverse?

"john m." wrote in message
m...
Thank you guys for the replies.
There is one problem. The propeller shaft has a roller chain coupling
that connects it to the hydraulic drive. I think that this type of
coupling does not take any axial load too well. The only place left to
take the axial load is the strut in front of the impeller. When I look
at the plastic washer I can see where the axial load eats away at the
plastic thrust washer. That is why I was thinking to replace the
plastic thrust washer with something more robust.

I have a folding prop, so in reverse its very slow. It also makes a
funny noise when the shaft pulls on the roller chain coupling, but so
far I never had a problem with it.

This whole installation sounds 'Rub Goldberg' and I can't imagine any
professional builder or boat yard doing such an installation where there is
no proper thrust bearing.

As I stated earlier in this thread, I suspect someone, in the past, has
replaced the OEM hydraulic drive motor with this chain drive system.

I find no fault with the chain drive if there is no way to get a hydraulic
motor down into the space. It's hard to say without seeing the
installation..

However, to salvage this installation, I would recommend putting a thrust
bearing on the forward (inboard) end of the shaft and the bearing should be
mounted to some substantial member in the bilge. This would have to be
glassed in and should be able to absorb both the forward and reverse thrust
of the shaft.

Even though the engine is only 15hp the thrust is not to be taken lightly
(literally). If it move the boat, then there is a mechanical force against
the hull or in this case, the strut, IMHO.

Steve
s/v Good Intentions