Take a look at the cost of replacement. As I recall replacing the gas
engines in the mag article included the engines, transmissions, struts,
motor mounts props instruments, and cutlass bearings (everything but the gas
tanks) and the total cost was about $80,000. If you are capable of doing
your own installation (and have the time) you might cut these costs in half.
If you expect to put a lot of miles on your boat and your boat is a classic
the reduced fuel costs, tune up costs and increased resale value might make
this pay.

I am also Carver owner (1987 3257 Montego) I met a guy who dieselized his
Montego (beautiful installation) did a lot of his own work and it still cost
him $50K both our boat and his are in very nice condition. We put a teak and
holly sole in ours ($2.5K). A broker said given the market for used Carvers
(which is good) we had increased the value of our boat more than he had.

One last thought, a guy at our club just bought a very nice TollyCraft 40.
Immediately replaced the 454 V-8s with diesels even though the 454s were in
good shape, (cost well over $80K) but the diesels are "shipier". Boating is
not a rational activity, go with what turns you on.
"Rod McInnis" wrote in message
...

"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