What Prop?

[Thompy_04]

I posted earlier on the Seahorse Motor 9.5 and was wondering about prop selection.... Any answers would help. Want the best top end, not so much out of the hole.... thanks.

 

[cobra 3.0]

Re: What Prop?

Without any details like size and weight of boat, rpm at WOT(full out), number of people you will be carrying, it's a guess at best.<br /><br />Here are some possibilites:<br /><br /> http://www.propline.com/Select-Boat...ropellers/Evinrude_Johnson_Outboards/6_15.htm

 

[Mercathode]

Re: What Prop?

What year 9.9?

 

[Thompy_04]

Re: What Prop?

Its a 14' V-Bottom aluminum boat, 2 people aboard and the operating RPM is between 4 and 5k.... By the way its a 1970 9.5 Hp, not a 9.9. Trying to match things up so I can get some more speed, not so much out of the hole.

 

[cobra 3.0]

Re: What Prop?

What's the pitch on the prop and the rpm at WOT now? Knowing the ACTUAL rpm at WOT(wide open throttle) now, is essential in determining prop selection. You can check it by installing a tinytach.<br /><br /> http://www.tinytach.com/tinytach.html <br /><br />...or you can just use the next pitch up as a guess (e.g. if it's a 9" pitch go to a 10" or 11"). Props are usually described as diameter x pitch.<br /><br />Pitching too high may actually slow you down and lug the motor. Pitching too low will over rev it out of it's rpm maximum range and eventually kill the motor.

 

[Thompy_04]

Re: What Prop?

With 2 people in the boat, you can tell the RPM's aren't to the normal operating WOT specs. I tried the boat out today with just myself in it and you could tell a differnce in RPM. Was louder and "whined out" better. With more people and gear in the boat, it seams to bog down or not run at its potential. This to me would suggest I need to drop down the pitch, right now it has the stock prop 8 1/8" diameter, by 8 pitch. Does this mean I need to drop down to less pitch?