General rule of thumb is a 100hp engine uses 10gals per hour at WOT. 200hp
would be 20gals per hour at WOT. I had a 21 foot Scarab with 350cid rated
at 270hp that would run about 7-10 gph around 3000rpm and I was going near
40mph. Top speed was 60mph. If you want to go faster and save gas then
consider buying a tunnel hull or ventilated V-hull type boat. Both type
hulls are geared for performance boaters because the advantage is reduced
hull friction, which means lower fuel usage at cruise RPM. My boat runs
100mph+ and at that speed it sucks gas, but at cruise speed of about 50mph
it only uses around 7gph.


"simon gilder" wrote in message
. uk...
Hi Group

I'm the owner of a nice example 1989 Bayliner Capri with a 2.3 ltr cobra
omc
engine.
Now my first thought when i bought this boat just over a year ago was that
it was going to
economical.
The boat has not had a hard life and is all serviced.
With a different prop top speed is 34 mph tops but this is screaming the
engine.
I guess at this speed i'm probably using what 5-7 gals.
My thoughts are now that i cant be doing the engine any good running at
max
revs and only acheiving 34 mph tops,so i'm considering selling up and
buying
either another Bayliner with a 4.3ltr or 5ltr engine.
My question is i guess,am i going to be in for a nasty shock when i
realise
that,that fuel consumption has at least doubled?
I've been told that a larger engine would'nt be working as hard and could
be
as economical as the smaller 2.3ltr.
Also,would a larger engine last longer if serviced propably as it would'nt
be working so hard.
Any thoughts or answers would be really appreciated.

Thanks for reading.

Simon