Steven Shelikoff wrote:

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

Again, here you're assuming laminar (or at least unidirectional)
flow. When inserted into a laminar flow stream, and angled surface,
such as a rudder, will certainly be subjected to a force related to
the mass of the fluid deflected. Fluid flow on the 'suction' side is
nowhere near laminar, and will in fact be totally non-uniform around
the rudder. All fluid will be redirected immediately upon clearing
the rudder, and the resulting reaction force is parallel to the
boats centerline.


Consider, also, that *if* fluid drawn over a rudder by a prop have any effect
on the rudder, mariners would all know which direction the stern moved with
which rudder position. Even the guys who insist pulled water affects a rudder
don't have a clew which way the boat turns. indeed, the "good professor" was
reduced to claiming that friction in the rudder bearin made the difference.


Consider the fact that fluid drawn over a rudder by a prop may have an
effect on how the stern moves,

It *may* for a brief instant until an equilibrium is reached and the
pressure equalizes on both rudder surfaces (remember, water is *not*
elastic in the way air is, so you can't create a vacuum in water
like you do in air - if you do, you cavitate and dissolve gases come
out of solution until the partial pressures equalize and/or until
water 'fills in the void' and the gases redissolve).

but one that is much less then prop walk.

Many orders of magnitude less IME and IMO.

Keith Hughes