89' Evinrude Evinrude 9.9 prop?

Mr.Stuart

Mr.Stuart

Senior Chief Petty Officer
Joined
Jul 18, 2007
Messages
701
I've got an 89' Evinrude 9.9 with a 10x7 prop on it, it was a long shaft used as a trolling motor on an 18 foot boat, and I converted it to a short shaft to use it on a 12 foot aluminum boat.

is the 10x7 the correct prop to use with this outboard on the 12 foot boat?
is there going to be any benefit to going to a stainless steel prop?
what would be the best size and pitch for general cruising with this outboard on the 12 foot boat?
 
Silvertip

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: 89' Evinrude Evinrude 9.9 prop?

Stainless steel on a 9.9 motor is akin to putting mag wheels on your garden tiller. Looks nice but no practical advantage. Since you have no tach, you could install a "Tinytach" temporarily or permanently to get wide open throttle RPM readings with an average load. Only then will you know what works best with the boat, load, and water conditions.
 
Mr.Stuart

Mr.Stuart

Senior Chief Petty Officer
Joined
Jul 18, 2007
Messages
701
Re: 89' Evinrude Evinrude 9.9 prop?

Silvertip said:
Stainless steel on a 9.9 motor is akin to putting mag wheels on your garden tiller. Looks nice but no practical advantage. Since you have no tach, you could install a "Tinytach" temporarily or permanently to get wide open throttle RPM readings with an average load. Only then will you know what works best with the boat, load, and water conditions.
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That sounds like a fair answer, it's pretty much the same thing on model airplanes when that prop question comes up, I looked up that "tiny Tach" I've not seen anything like that before, I'll have to pick one up, kind of a cool little instrument
 
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