Gould 0738 wrote:
I have it but it's on the boat, not available right now. I read it but
don't remember a discussion about what exactly causes prop walk. What
does it say?

Steve


That unequal blade thrust is the result of the difference in effective pitch
between the descending and ascending blade when a propeller is rotated on an
angle, (90 degrees from the angle at which the shaft exits the shaft log)
though a horizontally advancing medium (water under the boat).

(Page 143 in my 1985 edition, may be different in later versions)

Thanks Chuck. (Damn ... G more people are reading this thread than I
thought).
hmmmmm ... If I'm reading this correctly, Chapman is saying the shaft
must be angled "down" from the horizontal flow of water, and this is the
"root" cause?
UHOH. I disagree that an angle down or up for that matter, makes a
difference to the root cause. I do agree that it MAY increase propwalk.
I also agree that the main cause appears between the upward and downward
ascent of the blade, but feel that the main difference occurs between
090-180 and 270-360 ( eg I believe 180-270 is marginally more
efficient than 000-090).
Thanks again

otn