wf3h wrote:
OK here's a little topic for discussion

If you're going from point A to point B it seems you'd want to know how
much gas you're going to use. And that leads, by definition, to MPG (or
in the case of boats, GPM).

Most fuel curves, however, are for GPH...how many gallons per hour a
boat burns. That makes sense if consumption....MPG...is relatively flat
(which for many boats, once they're on plane, it, relatively speaking,
is).

So why GPH instead of MPG? Also, the value that seems to make the MOST
sense is G/MPH...that is, how much gas you burn at a certain speed, per
hour. That combines most of the info you'd need to get from point A to
B if the consumption curve is flat.

Just curious...

It can be pretty consistently established that at XXXX RPM, an engine
will burn Y GPH.

In real life it cannot be consistently established that at XXXX RPM a
boat will always travel the same number of miles or nautical miles. The
effects of wind, and most especially current, will increase or decrease
the number of miles traveled in an hour.

I think a second possibility for using a different fuel consumption
standard than that normally used for land vehicles is that the figures
for boats, when compared to a car or a truck, are pretty dismal. 4-5
nmpg could be considered exceptional fuel economy for most boats (some
big cruisers get 0.5 nmpg or thereabouts), but even the wrost gas hog
of a Hummer or what not probably gets 8-10 mpg on land. Then again,
that Hummer isn't operating at 80% of rated RPM, uphill, in high gear,
everywhere it goes and it would need to be to make an accurate
comparison.