On Fri, 16 Apr 2010 13:38:43 -0700 (PDT), Frogwatch
wrote:

Thus a deep V and a
flat hull at the same speed on a plane should get the same mpg if they
weigh the same.

That is not the way it works. The boat with a flat bottom, or at
least a flat after section, will require much less power to bring it
up on plane. Take a look at the direction of the thrust vectors of
the hull against the water and you'll understand why. The deep-V
hull is pushing a lot more water out to the side. In return you get a
much more gradual re-entry when coming down off a wave. I once owned
a Bertram 33 sportfish which has a classic deep-V hull. It had a
wonderful ride, even going through a 3 or 4 ft chop on full plane, but
it also burned 2 gallons per mile.