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Walter Guinon said-


>Let me first say that I like prop walk, it makes landing port side to much
>easier.

George comments- I agree. I berth port side to also. When I engage reverse,
the stern shifts sideways to port and snuggles nicely into the berth. My
propellor is righthanded, turning clockwise (seen from aft) when going
forward.

>I beleive the primary cause is the deviation of the shaft angle from the
>horizontal.

My prop shaft goes downhill from engine to propellor, and I think every
other craft, including Walter's, will be the same.

>In the extreme case with a vertical prop shaft, the reaction to the
>shaft torque tends to YAW the vessel.

Yes, but which way would it yaw the vessel? Seen from below, a propellor
driving in the ejecting-water direction (which would be "forward" if we
hadn't turned it to point vertically down) will, looked at from below the
vessel, be turning clockwise. So the reaction of the torsion on the prop
shaft would be to yaw the vessel, as seen from below, anticlockwise. This
would push the stern to port: the opposite way to what we find with a
righthanded prop driving forward.

So that can't be the mechanism involved.

George Huxtable


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contact George Huxtable by email at george@huxtable.u-net.com, by phone at
01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy
Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
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