All right, my boat is not a hot rod as top end with two people in the boat is 55mph. I took the boat out the other evening just before dark and the water was glass. The ride was fantastic, but the best I could do was 46mph.
RPM was the same (4200) and it didn't matter where the diverter was.
I guess I've never really paid attention before when the water was smooth because I usually have the wife and kids in the boat and won't do hard runs. Is a 10mph scrub of top speed common in very smooth water? The boat felt heavy as hell.