I have a 7.4 L MercCruiser Engine on my 29 ft Bayliner. While on
plane, I know the fuel usage for cruising RPM and max speed RPM.
SInce I do not have any gear changes, I have been assuming fuel usage
(gal/hour) is linear with RPM and I can extrapolate to lower RPM than
crusing. Is this a good approximating assumption?