new prop by-product

I installed my new 14x10 fixed 2 blade prop on my Cal 31 and it is great. I am getting 6.1K at the specified RPMs (new bottom paint too) and an pretty happy. Less noise, less vibration. EXCEPT Now I have a strange pull to starbord on my tiller. It is pretty pronounced and if you hand steered the boat on the motor for a while it would get old fast. About 5-10 lbs of pull. It does not happen when sailing. Anyone know why this might happen? Chris

I believe this is called prop walk. like the turning wheels on your car, the propeller tends to move the transom in the direction created by the side thrust of your propeller in the direction it is spinning. This is exaggerated by inefficient stock cal barn door rudders, which are hit by the side forces of the water, pushing the rudder over to the side of the wash. The stock barn door rudder profile is "famous" for easily stalling. When we changed California Girl (Cal 40) over to the Schumacher Elliptical Rudder, (narrower, deeper and stall surfaces removed) much of this effect went away, either because less water hit it's narrower profile, or the rudder was more efficient and tracked better. dEmO STILL stuck in Canada Saving the World From: Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com] On Behalf Of sculler2000 Sent: Monday, May 19, 2008 11:32 AM To: Ca… [at] yahoogroups.com Subject: [Cal_Boats] new prop by-product I installed my new 14x10 fixed 2 blade prop on my Cal 31 and it is great. I am getting 6.1K at the specified RPMs (new bottom paint too) and an pretty happy. Less noise, less vibration. EXCEPT Now I have a strange pull to starbord on my tiller. It is pretty pronounced and if you hand steered the boat on the motor for a while it would get old fast. About 5-10 lbs of pull. It does not happen when sailing. Anyone know why this might happen? Chris