"I'm obviously missing something but isn't 3600 RPM a really high number for a Cummins engine?"
Once again we are still not sure which engines he has 100%. If the charts I dug up are a match for his engines then the rated rpm is 3375 with no droop so that would be the high number.
Not sure of the exact engines yet = no way to really know.
More facts.
Yes the engines did turn 3350.
Both engines run the same.
Bottom, props and pods appear clean
Engines run cool, under 170 each.
Before doing anything rash (re prop or rerate the engines) I'll have Cummins out to check everything on the drives and engines. I'm not going to take all the stuff on the boat because I need that stuff and it would take days.
Presently wot is about 3050 and I usually will cruise about 2700 to 2800. 2700 is 15 knts and barely on a plane so I'll push it to 2750 to 2800 about 17 knts.
My own theory is the boat is over propped and if I want to get to 3300 I'll have to reduce the pitch.
My thanks to all who contributed and made me take a step back and review the problem before taking plunge perhaps in the wrong direction.
This.You use wot to get on the step? I would unload all the cr@p you are carrying and see if it still meets what it did when it was new...lead is good on a displacement boat but planing?
More facts.
Yes the engines did turn 3350.
Both engines run the same.
Bottom, props and pods appear clean
Engines run cool, under 170 each.
Before doing anything rash (re prop or rerate the engines) I'll have Cummins out to check everything on the drives and engines. I'm not going to take all the stuff on the boat because I need that stuff and it would take days.
Presently wot is about 3050 and I usually will cruise about 2700 to 2800. 2700 is 15 knts and barely on a plane so I'll push it to 2750 to 2800 about 17 knts.
My own theory is the boat is over propped and if I want to get to 3300 I'll have to reduce the pitch.
My thanks to all who contributed and made me take a step back and review the problem before taking plunge perhaps in the wrong direction.
The problem came over the first year and a half as more stuff was put on the boat and appears to have gotten slightly worse lately.
The problem came over the first year and a half as more stuff was put on the boat and appears to have gotten slightly worse lately.
Interesting. Might not have come up with that one.Have them check that both pods are aiming right. If angle is wrong they will fight each other and reduce speed.
Thanks Jeff
Did you go down in pitch or diameter?