Prop size F40/40
Prop size F40/40
I'm trying to replace my max prop on my F40/40 (needs referb) with a 3 blade MP3 prop. My owners book says the original prop was a 20-13 but doesn't say 2 or 3 blade. Does any 40/40 owners know the original size prop and would 20-13 three blade be correct? Any recommendations?
- GeoffSchultz
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Re: Prop size F40/40
Based upon my calculations, it should be an 18" prop as you don't want to exceed 95 ft/sec at the prop tip. An 18" prop develops 95 ft/sec at 2800 RPM using a KBW10-E transmission with a 2.33:1 reduction. This is also right at the prime part of the curve for power & fuel consumption, so I'd bet that's the right size.
-- Geoff
-- Geoff
- GeoffSchultz
- Posts: 1136
- Joined: Thu Dec 04, 2008 8:39 am
- Location: BlueJacket: Guatemala
- Contact:
Re: Prop size F40/40
According to the manual the original prop was a 2-blade 20x13 rh. However, based upon my research that's too large as you don't want to exceed 95 ft/sec at the blade tip. The Yanmar 3jh2-tbe that my 40/40 comes with has a sweet spot for fuel consumption and torque at about 2800 RPM, which equates to 105 ft/sec, which is too fast. Thus I believe that a smaller, higher pitched prop would be better.
Re: Prop size F40/40
I just had my F 40/40's, 3 blade 20 inch max prop refirbed by PYI. What pitch do you use? 16 or 18 degrees?