Jack, New Prop Test Results...

Posted By: Pete M P-23
Date: 5/2/09 7:47a.m.

Report: outside forum guidelines

In Response To: Great, I've been playing with my motor tilt.. (Jack, H23.5, SecondSojourn,Clermont Fl.)

Installed the new "6.5 in per rpm" pitch prop on the 9.9 Merc. Tested the new prop and found no difference in top speed forward or reverse! The engine does run at higher rpm at the top speed however. This is not surprising considering the lower pitch number. Will put a tach on it to check for over-speeding. The engi1ne is rated at 6000 rpm max. Subjectively, at lower rpm the prop had better "grip" with less cavitation. This may help when applying partial throttle in reverse. I do not use full throttle for routine operations anyway - usually 2/3 when motoring. The before and after photo shows the badly pitted and eroded 9 year old prop and the new prop. Jack, this probably does not help much, but if I had it to do over, I would have selected the next higher pitch prop. Pete