Which Is Better Performance?

[JoeS]

50 mph @ 5200 rpm or 49.5 @ 5600 rpm?? Max rpm for Mercury XR6 150, 5600 rpms.


Thanks!!

[THROWINWOOD]

ITS ALWAYS BETTER FOR ENGINE LIFE TO BE TURNING AT OR VERY CLOSE TO THE MAX REC. RPM .AT 5600 YOU SHOULD BE LIGHT( 1 PERSON ,LIGHT FUEL,GEAR ECT) THEN WHEN YOU LOAD UP YOUR RIG YOU KNOW YOUR RPM WILL BE OK . IF YOUR AT 5600 WITH A TYP. LOAD WHEN YOU DROP FUEL ,PASSENGERS,ECT YOU'LL BE OVER THAT 5600 TARGET.
MY 2CENTS
DAVE

[PropBoy]

Joe, my opinion is you ought to prop for your "normal day on the water" load. Your prop ought to be designed to fit "most" situations in which you use your boat and then you adjust how you run your rig for the exceptions.

My Opti manual says that you want to prop so you are in the upper half of your motor's rpm range as documented in the specs page of the manual.

I tested mine fairly heavily loaded which is how I usually run my boat. My max rpm's according to my manual is 5750 and I topped out at about 5700 rpm's. My Pike 18 weighs 2700 loaded for fishing (main motor 450, kicker 100, bow troller 50, 3 batteries 200, boat 1250, fuel 250, two 200 pound passengers, etc.). Plus 2 full live wells which I did not include in that weight.

I figure I should be ok even if the fuel tank ever gets down close to empty ... I will just watch the rpm's to make sure I don't overrev. Besides, I almost never run the boat with less weight in it. At times there will be a third fisherman as well (about 150 pounds), or one buddy of mine who is VERY heavy, or one or two big dogs.

I still may try the 21 pitch prop to see what difference it makes over the 19 I am running. I think based on what I am told by folks on here the 21 would drop the rpm's about 300 to 400 which would put me in the LOWER half of the range with my normal loads ... a place I don't want to be. But only experimenting would tell me for sure.

Let us know what you decide and how things wind up.