Prop recommendations needed!

Joined
Apr 19, 2009
Messages
19
Hi all,

I've got a 1986 Johnson 9.9HP Outboard motor (model# J10RCDB).

I've seen a lot of good information posted here about tweaking motors, and I'm now in need of some advice. I've purchased a TinyTach and have averaged about 5800 RPM at WOT on my boat, which is a 14' Springbok. At the time, I was moving at about 31Kmh, so said my Humminbird.

These runs were with just me in the boat, and half the time it will just be me, but the other half of the time, I'll have a passenger sitting up front. I do not have info as to what prop is on the boat now. It is however pretty beat up. I'd like to replace it, and am wondering if anyone would be able to recommend one, or if it's essential that I know first what's on there now?

Thanks for any and all information!

Best,
Mark
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,003
Re: Prop recommendations needed!

I do not have info as to what prop is on the boat now.

Ayuh,... Look Closer,... That's Necessary Info...
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Prop recommendations needed!

Check closely for a number - - X - - Diameter X pitch.
Your rpm is good,I'm guessing speed at about 20-21 mph.also pretty good.
A prop shop can measure it for you and repair it if not damaged to badly.
 

hwsiii

Commander
Joined
Jan 25, 2009
Messages
2,639
Re: Prop recommendations needed!

Digital, it appears to me you are running either a 10" pitch prop with about 17% slip, but it could be a 9" pitch with 7% slip. I believe it is a 9" Pitch though.

H
 
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