Originally Posted by markpierce
Hull speed is no-way near efficiency. Slowing down a notch can easily reduced fuel consumption by 50% and more.
Published data for AT34, 1400 RPM, 8 knots, 2.1gph. Mathematically, the sweet spot is about 7.5knots. BUT that is with 1/2 filled fuel tanks, 200gal and empty boat. Mine is a live aboard with lots of additional stuff on board so, fuel usage will be much greater at the sweet spot and far different from the published data.
Of course, this will also be effected by wind and waves and currents.
So 'hull speed' is just theory but a place to start.