wrote:
Howdy group,
All the yachtsmen I know who run a diesel use only 'diesel fuel', which
is light and expensive. However, in the merchant navy we use bunker
fuel whenever we're going to be running the engine for a long time,
without varying RPM.

It's thicker than molasses at room temperature, but when suitably
heated, it runs enough to be used in a diesel engine. It also costs a
fraction of regular 'diesel fuel' (aka "Champagne"). The engine is
started with light diesel fuel until it's running hot enough, then the
fuel mixture is gradually changed over to bunker. If the ship comes to
manoeuvering conditions, then the mixture is switched back to light
fuel. They always go back to light fuel before shutting off the engine,
too, to 'clean' the insides for the next start-up.

Now I'm wondering why we don't do this in cruising yachts, where the
engine is running constantly for days, especially considering the fuel
prices of late. All one would need is a heated holding tank and a way
of adjusting the fuel mixture. Then again, I'm not a marine engineer.
Am I missing something?

Regards,
-Max

THere's more than the heated day tank, you need separators
to deal with the sludge, a place for the sludge (sludge
tank), etc. etc. Most pleasure sailboats turn off the
engine and sail so you don't have a ready source of heat to
keep the fuel tank warm....

Oh, small engines just won't run on heavy fuel either. The
fuel pump on a small (say 50 HP) engine pumps out such tiny
amounts of fuel with each stroke that it probably couldn't
meter it if it were heavy fuel.

Evan Gatehouse

OK I'll let all my chemistry ignorance hang out and ask. Would it be
practical to brew your own deisel by mixing bunker with regular
gasoline? Would the savings be worth it?

wrote:
Howdy group,
All the yachtsmen I know who run a diesel use only 'diesel fuel', which
is light and expensive. However, in the merchant navy we use bunker
fuel whenever we're going to be running the engine for a long time,
without varying RPM.

It's thicker than molasses at room temperature, but when suitably
heated, it runs enough to be used in a diesel engine. It also costs a
fraction of regular 'diesel fuel' (aka "Champagne"). The engine is
started with light diesel fuel until it's running hot enough, then the
fuel mixture is gradually changed over to bunker. If the ship comes to
manoeuvering conditions, then the mixture is switched back to light
fuel. They always go back to light fuel before shutting off the engine,
too, to 'clean' the insides for the next start-up.

Now I'm wondering why we don't do this in cruising yachts, where the
engine is running constantly for days, especially considering the fuel
prices of late. All one would need is a heated holding tank and a way
of adjusting the fuel mixture. Then again, I'm not a marine engineer.
Am I missing something?

Regards,
-Max

THere's more than the heated day tank, you need separators
to deal with the sludge, a place for the sludge (sludge
tank), etc. etc. Most pleasure sailboats turn off the
engine and sail so you don't have a ready source of heat to
keep the fuel tank warm....

Oh, small engines just won't run on heavy fuel either. The
fuel pump on a small (say 50 HP) engine pumps out such tiny
amounts of fuel with each stroke that it probably couldn't
meter it if it were heavy fuel.

Evan Gatehouse

Proberly not, as the more heavy fuel also carry acids and sulfur there
simply are more dirt in the heavy fuels, something that is no problem
in a huge ships engine undertaking maintaince on regular times ,where
the pistons are houled and the rings cleaned every 2 month and, you
easily end up with an engine blocked by unburned remains, valves that
will not close well, all in all , what you think you save can add extra
costs while the engine suffer. ---- beside when the engine are not made
for the fuel the smoke can turn out to be a major problem.
Also even the old slow running engines are made for a particular fuel,
the jets in the carburator aswell as the spray holes in the diesel
engine, are made so that a wrong fuel will only caurse trouble , the
engine will turn out being very "dirty" and esp. more modern engines
will soon fail or the engine will soon be vorn out.

that makes sense thanks

Proberly not, as the more heavy fuel also carry acids and sulfur there
simply are more dirt in the heavy fuels, something that is no problem
in a huge ships engine undertaking maintaince on regular times ,where
the pistons are houled and the rings cleaned every 2 month and, you
easily end up with an engine blocked by unburned remains, valves that
will not close well, all in all , what you think you save can add extra
costs while the engine suffer. ---- beside when the engine are not made
for the fuel the smoke can turn out to be a major problem.
Also even the old slow running engines are made for a particular fuel,
the jets in the carburator aswell as the spray holes in the diesel
engine, are made so that a wrong fuel will only caurse trouble , the
engine will turn out being very "dirty" and esp. more modern engines
will soon fail or the engine will soon be vorn out.

I don't know the chemical gotchas, but I'd suggest that

1) Finding Bunker C in the amounts you want and

2) avoiding the highway taxes and other costs levied on gasoline

would probably leave you spending more, not less. Particularly if your
time is worth anything.

You'd end up wiser, but grubby.

Roger

http://home.earthlink.net/~derbyrm

"Drew Dalgleish" wrote in message
...
OK I'll let all my chemistry ignorance hang out and ask. Would it be
practical to brew your own diesel by mixing bunker with regular
gasoline? Would the savings be worth it?