Switching Prop to Different Pitch

[ghostrider]

I have a Merc 9.9 and the hub on the prop has spun. The number on my spun prop is 48-42522 9. I have access to a prop number 48-42522 11. Both props have 8 splines. What will the operating characteristics be with the pitch difference of 2 degrees. All help and suggestions will be appreciated. Thanks in advance!!

 

[walleyehed]

Re: Switching Prop to Different Pitch

it all depends on what your WOT RPM was with the old prop. It will slow your time-to-plane.

 

[ghostrider]

Re: Switching Prop to Different Pitch

Thanks for the quick reply Kenny! With the slowed time to plane, are you suggesting that the hole shot will be gone? If this is all that is lost I can live with that. I never have been a drag racer anyway, however, I do want to maintain top end performance.

 

[walleyehed]

Re: Switching Prop to Different Pitch

It will take longer to plane out, yes...the question we have is: Are we going to be operating with-in the specs of WOT with the higher pitch prop. We don't want to lug the engine.<br />You most likely don't have a tach on that small engine, and I would say if it planes the boat in a reasonable fasion, it should be ok...

 

[ghostrider]

Re: Switching Prop to Different Pitch

It appears I need to determine my wot rpms before I do more than sin a prop.

 

[DJ]

Re: Switching Prop to Different Pitch

This will help with your rpm question. See link.<br /><br /> http://www.tinytach.com/origgas.html

 

[ghostrider]

Re: Switching Prop to Different Pitch

Thanks for the tach info DJ. I'm not sure if I'll buy one though. Right now I'm just trying to keep this little motor going. I only use once a year on a trip to Reelfoot Lake in TN. I was there when the prop spun three weeks ago. I know better than to go on a trip without a spare prop, and I wont do it again.

 

[ZmOz]

Re: Switching Prop to Different Pitch

It is a really bad idea to use an outboard without a tach, especially when changing the prop pitch. If you're not in the right RPM range, you'll soon need a new engine to go with that prop.

 

[ghostrider]

Re: Switching Prop to Different Pitch

Thanks ZmOz! I intend to do this right the first time. Props are a lot cheaper than motors.