Can I use a 2 blade prop instead of the original 3 blade prop?

[dheitman62]

I have a 1965 Johnson 9.5 hp model MQ11c. This motor uses a 3 Blade aluminum prop (OMC #377635). I think the hub in this prop is starting to slip. I have a 2 Blade prop from a 1969 6 hp engine that has never been used (OMC#380958) It installs the exact same way as the 3 Blade prop using a prop nut and cotter pin. I would like to know if I can use this 2 Blade prop on my motor. What difference would only having 2 Blades make and, if I did use the 2 Blade prop, could it damage my engine?

Thanks in advance for any advice on this matter.

 

[sutor623]

Yes it could damage the engine.If that prop was made for the 6hp and the 3 blade is made for the 9.9, the 2 blade will be spinning much faster which will overrev the engine. That 3 blade is an 8 pitch, and the 2 blade is a 7 pitch.

Even if those props were the same pitch, the two bladed prop would provide less resistance on the motor, and you would lose top end and rev the heck out of your motor at full throttle!!!!

Don't do it.

 

[dheitman62]

Thanks for the advice Sutor. I definitely will not do it. I had a feeling it was a bad idea.

I'll just have to keep looking for somewhere to get the prop that doesn't cost an arm and a leg. In the meantime, hopefully this prop doesn't leave me stranded and limping back to the boat ramp with my trolling motor.


Thanks again, Sutor623

 

[Faztbullet]

Everything being equal, a two blade propeller will run faster. One less blade disturbing the water. But they tended to vibrate more, and be slower accelerating, because of the smaller blade area. And yes that prop will work as I use one on my 1969 9.5hp duck boat motor...

 

[racerone]

Depends on the boat / load.------There is a risk of over reving the engine with the 2 blade.----Your location ?

 

[ondarvr]

Either buy a new one or just have the hub fixed.