I'm running a '96 115 HP Merc 2 stroke with a stock 21P AL prop on a 17' BW Montauk. With 4 adults aboard, at 5,000 RPM, my speed on GPS is 30 mph. Mileage is 5 mpg.The drive is trimmed down to maintain even plane. I have no trim tabs or hydrofoil. I expect a prop change would improve this poor...
