The Parker planes in the 16-17 mph range, but if the conditions warrant,
I typically "cruise" the boat at 25-30 mph. The engine seems to have a
wide "cruise groove" range

Your Parker gets better fuel economy at 25-30 mph than on plane at 16-17?

Very unusual, indeed. I'll have to see if there are some test results that show
others have had a similar experience in the same boat. Could it be that trim or
something is unnaturally and seriously *reducing* your Parkers nmpg at the
slower velocity?