what is the best way to measure the optimum "cruising speed" of a motor boat for best gas mileage?

Question

We have a 26 foot cruiser - needless to say, we want to use the least amount of gas possible while running it.

Answer 1

just after you plane off. this is when the bow levels off and your making less wake (pushing less water b/c the hull is higher out of the water)

Answer 2

Run your boat till it planes out and then run 3/4 throtle for optimum cruising and best gas milage