In agreement with jrem. We have a hardtop, full curtains, bottom paint, "normal" load, 15 3/4 x 15 stainless prop, and here's our figures:
22 knots @ 4,300 RPM
25 knots @ 4,600 RPM
30 knots @ 5,100 RPM
34 knots @ 6,000 RPM (WOT)
With my factory 15 1/2 x 17 stainless prop we burned 70-80...