On Fri, 19 Sep 2008 08:08:43 +0100, Mike Pearce
wrote:

On Sun, 14 Sep 2008 18:46:52 -0700, Rick Cortese
wrote:

Slow in the group so I figured I'd waste some bandwidth. Checked the
mileage and my boat with an 18hp two stroke only makes 2-3 mpg.

A more realistic measure would gallons per hour. Miles covered per
gallon is subject to too many variables - tides/current, wave height
and frequency, wind speed and direction, etc.

My boat, a 42' Moody, a substantially-built sailboat, uses around 1/4
- 1/3 of a gallon per hour. Distance covered in that time - anywhere
from 2 to 10 nautical miles.

Yes, fuel useage on a boat is more commonly expressed in gallons per
hour. It can still be useful to express it in miles per gallon, too.
My boat, with a 4-stroke outboard uses roughly 1/2 gallon an hour at
full power. I keep a log book, and over the years, I've been able to
determine that my boat gets about 10 statute miles per gallon on
average when traveling on motor alone at around hull speed or a little
slower. Obviously, conditions will have an effect.