With a 35 HP
engine, you're not going to set any speed records, but the
boat should be very
fuel efficient. I'm guessing you will find a sweet spot for
fuel consumption vs speed at 6-6.5 knots. You should also be operating the
engine at it's sweet spot for load, which is much better for the engine than lugging it along underloaded.
My 95,000 lbs.
boat moves at 4 knots with a 40 HP wing engine and runs at 7.5 kts at about 50%
power on the 135 HP main.
Good Luck,