Consider that it doesn't really matter as long as there is flow of fluid
media over the rudder.

but it does, because the rudder and prop are hooked together. If the prop were
fixed as to direction, the rudder would turn into it until the movement
stopped.

Consider the fact that fluid drawn over a rudder by a prop may have an
effect on how the stern moves, but one that is much less then prop walk.


the "good professor" argued that without friction in the rudder bearings rudder
would move. I say it doesn't.

plainly, a shot of forward throttle with the rudder turned turns the stern, and
all (most?) mariners know in which direction the boat will turn from
experience. nobody can remember which direction a boat will turn with a shot
of reverse throttle because nobody has seen it.