"KJEJ Harris" wrote in message
ogers.com...


. By that I mean is the improvements in efficiency in engines enough
over the last 20 years that I would be ahead in gas savings by getting rid
of them now?


For your application, the improvements are pretty small.

Modern computer controlled, fuel injected engines will significantly reduce
emissions, start easier, and operate more efficiently over a wider range of
altitudes, temperatures, and speeds. Assuming that your boat doesn't
deviate much from sea level, and doesn't operate at freezing temperatures,
and most of your cruising is at a constant speed, you won't see a dramatic
improvment in fuel economy.

If you rely on the engines and having them fail could put you in danger then
I would say to swap them out before they die. If having an engine die
simply means that it will take you a bit longer to get back to your dock
then I would be tempted to run them till they didn't run anymore.

As far as switching to diesels: You would have to put a lot of hours on the
engines to recover the cost. If you replace the existing engines with a
similar size gas engine then you can reuse the transmissions, shafts and
prop. If you change to diesels, you will need to modify or replace the
fuel tanks (they will need a fuel return line), replace the transmissions,
make new motor mounts, new dash insturments, etc. It can end up costing you
an extra $10,000 to switch to diesel. That will buy a lot of gas.....

Rod