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