Re: cruising and top speed
I believe it is more about hull efficiency than engine efficiency.
Most of my experience is with airplanes (flight instructor), and I see a lot of parallels between airplanes and boats in this regard. Too slow and you have a lot of induced drag (a boat "plowing" before it gets on plane), too fast and you have a lot of parasitic drag (friction). Over the course of a couple of years I did a lot of testing with my fish-n-ski in regards to fuel efficiency. It tops out around 45 mph and can go as slow as about 15 and stay on plane. My best fuel efficiency is around 25 - 30 mph, which is a good bit more than "just on plane".
I haven't started figuring fuel economy yet for my Checkmate since it's so darned difficult not to put my foot all the way into the throttle once I get going and get that big grin on my face (though I do know that at WOT I swear I can see the fuel gauge moving).
