A paddle wheel has it's top portion out of the water, a prop doesn't.


"engsol" wrote in message
...
Being old and senile, I have to work things out with a mind
picture.

Re prop-walk...if I have a prop with flat blades aligned fore
and aft, I essentially have a "paddle wheel". If I turn the prop
clock-wise (as viewed from the rear of the boat), I'd
expect the stern to go to the right. Reversing the direction
would obviously make the stern go to the left.

If I re-pitch the prop so the flat blades are at right angles to the keel,
(cross-ways), I'd expect a bit of froth, but not much in the way of
stern reaction.

When I consider a *real* prop, the blades are aligned between
the two extremes above, and I'd expect the stern reaction to
also be between the two extremes.

Norm B