On 2008-06-26 17:52:24 -0400, "Bob999 via BoatKB.com" u44405@uwe said:

Jere Lull wrote:
you might investigate something a dockmate said *drastically* improved
his consumption: Switching to higher gearing and larger props.

Wish I could remember more, but in the sailboat world, a similar change
just about doubled economy.

From the other commentators, it appears that monkeying with the fuel
system is a non-starter. But the props I've reviewed were a tradeoff
between diameter and pitch (higher pitch/smaller diameter). Do you
have to do both at the same time? Like if I buy a new, higher geared
lower unit does it come with a larger diameter prop?

Oh, lower unit.... I don't know those beasties much at all. But am
fairly certain he had twin I/Os. My recollection was that he changed
the gearing in the existing transmissions, then added larger props. I
could be wrong, but I'd say to go that route if at all possible. An
all-new unit represents quite a few gallons of fuel, even these days.

My personal opinion, remembering that I travel at less than hull speed,
is to fit the largest diameter prop possible, then find the pitch that
just allows you to max out in normal conditions. The shop doing the
work will either know how to calculate the proper dimensions and/or
they'll let you swap props if they guess wrong.

--
Jere Lull
Xan-à-Deux -- Tanzer 28 #4 out of Tolchester, MD
Xan's pages: http://web.mac.com/jerelull/iWeb/Xan/
Our BVI trips & tips: http://homepage.mac.com/jerelull/BVI/