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overpropped vs underpropped

13K views 45 replies 18 participants last post by  Lake Superior Sailor 
#1 ·
Hi,
I just had a new diesel engine installed, which seems to be working well.
I also have a max-prop propeller where you can change the pitch in 2 degree increments.

The target rpm at max throttle is apparently 3500-3600 for this engine according to the mechanic. I can make about 3260.

After signing off on the engine, and sending the warranty info to the mfr, the manufacturer is saying that I need to decrease pitch.

Doing the math from the prop manual, which reports about 7% rpm increase per degree, I would expect to be then underpropped, at about 3725?

What is the point? I can hit close to the target above and below the target rpm.
 
#46 ·
I have a diesel YSM8 it's governed, if the prop is too high a pitch She blows black,if the prop is too low the governer kicks in and the boat is slow.So the prop that gets the speed without the black must be right.K.I.S.S.Then you just pick the throttle speed!...Dale
 
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