My info indicates 1.85:1 5,000 -6000 rpm.
Keep in mind your slip calculation is only as accurate as the input numbers.
The only nuimbers you can be sure are accurate is the gear ratio and gps speed.
The prop size and max rpm and speed will tell pretty much what you need without a bunch of calculation. imo.
25 on a light reasonably fast boat will run about 29-31.Slip will be higher with a heavier boat/load.
thanks,thats the info i was looking for.Im running 30mph at 5250 rpms with a 13p stainless prop and 30mph at 4950 rpms with a 13p aluminum prop so obviously the ss prop is slipping more, i just couldnt calculate w/o the gear ratio.
Your motor would be happier closer to that 6,000 rpm figure I mentioned.
Which prop do you intend to run.The ss may require more rpm for a given speed but less throttle to get there.
I'm surprised that the ss doesn't load the motor as much or more than the al.
The ss prop is closer to the rated rpm and should be more productive through the rpm range producing better hole shot and better cruise speed control.
Its possible the same al brand and model in an a 12 could produce more speed and rpm.The 4950 is just too low imo.
