Join Date: Nov 2007
Location: Vancouver Island
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If the prop is turning in a clockwise direction (in forward) when viewed from astern then the bow swinging to port may be because the clearance between the top of the propeller and the bottom of the boat is insufficient and the prop is cavitating at the top. That might cause the boat to veer to port at higher speeds but be less noticeable at slow speeds because there would be no cavitation. It would likely be less noticeable when going astern because the revs are usually much lower (no cavitation).
That is my guess......
Thinking about it some more, the fact that you went from a three blade to a two blade may also contribute to the new cavitation. With two blades, the top blade may be cavitating while the bottom blade is biting introducing the prop walk. Of course with the three blade, whenever there was a blade straight down there wasn't one near the hull so cavitation was minimized.
There is a tide in the affairs of men,
Which, taken at the flood, leads on to fortune;
Omitted, all the voyage of their life
Is bound in shallows and in miseries.
Shakespeare, Julius Caesar IV, iii, 217
Last edited by Plumper; 06-10-2008 at 05:13 PM.
Reason: More thought!