It all depends. In a boat with a relatively long waterline length, say 34ft
and a relatively narrow beam say 10 ft. traveling at hull speed (say 7kts)
could be economical (say 3 nmpg) on a gas powered boat with 20% less fuel
consumption on a diesel.
However a beamy boat with a short waterline length (say 23ft) would only be
economical at or below hull speed and this would limit you to say 5kts.

Of course if you have a planing hull you have two economy peaks the first at
or below hull speed the second on a clean plane (say 22kts) However the
second peak is not a efficient as the first, and may not even be possible in
a chop or a seaway.

There are many many variables and "all boats are compromises". Some of the
variables are type of engine, size of engine, number of engines, hull
design, water line length, beam acronymic drag.

There is one constant people and manufacturers always seem to underestimate
their boat's fuel consumption, often by a large multiple.


"Brad" wrote in message
om...
Hello All,

Now I know that normally a sailboat would use a lot less than a
powerboat, and maybe that's not the right heading to use, but I am
currently looking at the possibility of buying one or the other type
of boat (used), and I am trying to get some info on boating long-term
on the Atlantic.

Although a powerboat would use oodles of fuel at a fast clip, any idea
of how much that would drop if traveling at the rate of a sailboat
(say 7 or 8 knots)?

The main reason that I am looking at the various options, is because I
have a spinal disease that prevents me from pulling, lifting, tugging,
etc. on anything more than about 10 pounds. I can get around on a
boat okay, but these other limitations require me to check out all
options. My thought (and I have never done much serious boating) is
that a powerboat would be easier on me physically, but I am concerned
about the comsumption of fuel while traveling. Fortunately I am tied
down to time, so if I have to travel at a much slower speed than the
boat is designed for, I can easily do so.

I appreciate any useful feedback,
Stryder