Sure, but he said to BACK OFF on the rpm, not put larger props on so the
  boat would go just as fast at lower engine speed. Increasing the
diameter of the tires to lower rpm while keeping the same speed is
hardly the same as backing off.

Mark

robert shawn feller wrote:
> ..........
> My theory of lowering RPMs a couple hundred or was also supported
> based on a professional I respect. My boat mechanic told me years ago
> to fight the urge to cruise at recommend RPM on my twin 351 engines in
> our cruiser, he said the recommended RPMs were to high...to always
> back off a couple hundred RPM. He has been doing this 40 years and
> says RPM conservation not only increase fuel savings but engine life
> in most marine gas v8 engines. Now one could argue his "theory" dosn't
> apply to vanagons but maybe it does. Again its just a theory like
> yours and Rons that may look good on generalized paper...but be
> different in the real world.
>
>