Prop, and Boat Stability

intrigueing

Cadet
Joined
Sep 28, 2003
Messages
11
Finally got my boat out for a spin. It runs really well, however I have a few issues that I would like to figure out. <br />1) The max rpm that I could get out of it was approximately 4400 (spec is 4500-5500) should I try a different pitch? <br />2) The boat planes well, does not pourpose, but does seem to want pull/tilt to the right under acceleration (even with more weight on the left). Turning the steering wheel to the left then back straight corrects the problem, as does backing the throttle down slightly. What could be causing this? <br />3) The steering seems over sensitive while at full throttle- kind of unstable.<br /><br />The boat is a 16 foot 1965 fibreglass clippercraft with a 1972 chrylser 85. The prop is a Michigan PR 76 Anyone know the specs from this prop? The prop has one blade that is a little dinged - could the prop be causing my drivibility problems? The boat went approvimately 30 mph with about 600 pounds of people and gear on board - no vibration. I recently had the lower unit off, I aligned the muffler straight - (it was at an angle before) could this cause the pull when accelerating? Should I look at a foil for the motor to make the boat more stable at speed, or are there other things I can try? Sorry there are so many questions, but I know you guys are up to it! ;)
 

ISkiH2O

Seaman Apprentice
Joined
Sep 18, 2003
Messages
39
Re: Prop, and Boat Stability

The muffler should be at an angle to counter the prop forces. Move it back and the boat should handle better.
 

wilkin250r

Chief Petty Officer
Joined
Feb 9, 2003
Messages
570
Re: Prop, and Boat Stability

Definitly try a different prop to increase rpms. The general rule is that a 1" change in pitch will change the rpms by about 200.
 

backdraft

Petty Officer 1st Class
Joined
Dec 29, 2002
Messages
266
Re: Prop, and Boat Stability

intrig , You need a prop with 2 inches less pitch. These motors will last longer if not run over 5200 to 5300. The exhaust snout should be angled left or right to compensate for the torque created by the prop. Play with the settings starting with the tab to the right a quarter inch or so when viewed from the rear. nevjb
 
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