Are you really getting 40mph via GPS reading?
Mine tops out at 30 mph via gps @ 4,100 rpms.
Or 30 mph at 4,600 rpms, with a different prop.
Maybe I just got too much fishing gear, gas, kicker motor and such.
I have a hummingbird depth finder, at 4500 rpm it says i'm doing 53mph, ha ha, not even close. Striped down with 3 persons maybe 40, she cruises nicely at 3500.
Please do not have a lot of faith in the depth finder speedo's. Use a gps...my Islander with 140 hp just on sunday with 4 men and fishing gear, 1/2 tank fuel, 10 hp kicker we hit 33 mph at 4400 rpm, Running a 19" pitch prop.
Airshot
