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