I have my truck undergeared at the moment and it ain't helping my mileage. Sometimes when I'm really nice to it I can get 17mpg. For a moment, happiness, then I remember to take off that 6% for gearing and it's back to routine indifference. <img src="/forums/images/graemlins/smile.gif" alt="" />

Lowering the gearing will make life easier on the motor and tranny if you keep the speeds down. Since you drive in the sand, smaller tires probably aren't the best solution for you, lower gearing is. The thing about the mileage is it just takes more energy to move all of that. Energy comes from the gas you burn so there you go. Make sure all the tires, trailer included are up to pressure and that's about it. Not sure of how tall your boat sticks up beyond the truck, probably not much if at all, but anything to help aerodynamics is also a plus.

Frank