Prop walk is a function of the asymmetrical thrust produced by the angle of the shaft / rotational angle of the blades vs the water surface. The more downward angle on the prop / the longer the blade has to travel going from bottom towards the surface compared to the blade that goes from top to bottom. Longer path = more thrust per rotation for that blade = unequal thrust.. Pretty simple concept. See here: http://www.castlemarine.co.uk/propwalk.pdf
Increasing either pitch or diameter affects prop walk and so does prop design. While efficient for sailing due to a typically smaller diameter, the Campbell Sailer is known for pretty bad prop walk.. With a little practice prop walk can be useful when you need to pivot or crab sideways. I use a Martec folder which is also known for dismal reverse / prop walk. For what I do, neither bothers me at all. When I don't want prop walk I just give it a smooth burst of reverse thrust then put it in neutral / glide precisely where I want. (I always back into my slip) Good luck, -Francois Rivard 1990 34+ "Take Five" Lake Lanier, GA.
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