rOn Mon, 01 Jun 2009 09:11:44 -0500, Richard Casady
wrote:

On Mon, 01 Jun 2009 19:13:35 +0700, Bruce in Bangkok
wrote:

If you do much cruising I suspect that you will wish you had an
inboard though. Or a bigger fuel tank. An outboard surely burns a lot
of fuel..

Four cycle spark ignition specific consumption is the same inboard,
sterndrive, outboard, long tail motor, sail drive, and airboat. Half a
pound pre hour per horsepower. As much as double for fuel cooled
racing mills. Getting the oxygen into the motor is the problem, not
fuel. A lean mixture uses all the fuel. A rich mixture uses all the
oxygen and gives maximum power and a wasteful fuel rich exhaust.
Flames at the end of the exhaust system. With fewer than one set of
jets per cylinder, carburators are inefficient, the reason why they
have disappeared from autos. Two four barrels or four two barrels for
a eight, a common arrangement for muscle cars. As it is wilth EFI, you
get enough fuel in the exhaust to require a catalytic [spell checkers
are grand] converter.

Try running the usual small outboard in a barrel of clean water and
see whether there isn't a bit of "slick" that forms on the surface of
the water. Remember the big hurrah about not allowing 2 stroke
outboards in lakes any more? Apparently 2 stroke outboards pass a bit
of their fuel straight out the exhaust.

Perhaps I should have specified 2-stroke outboard so I'll change
that to "the two-stroke out board motors that I usually see on small
sailboats as auxiliary power".


Cheers,

Bruce in Bangkok
(bruceinbangkokatgmaildotcom)