On Sat, 05 Apr 2008 06:51:26 GMT, Jere Lull wrote:

On 2008-04-04 05:01:39 -0400, "Edgar" said:

"Lew Hodgett" wrote in message
news:iMjJj.10032$s27.7854@trnddc02...

"Bruce in Bangkok" wrote:

read a reference to one of your posts, quoted in part by Roger, that
sounded as though the RPM was only unstable at low RPM, I remember
something about 1,000 RPM.


Most diesels need to idle in the 1300-1500 RPM area in order to generate
enough waste heat to prevent
"wet-stacking" which will cause glazing of the cylinder walls, creating a
VERY expensive repair.

Much better to cut out prolonged idling and get some load on sooner.
Start up, and by the time you have checked the exhaust for cooling water,
gone forward and cast off the mooring ropes the engine is ready to go.
In other words, just long enough to spread some oil around inside the
engine.
If you cannot get load on for some time then stop the engine until you are
ready.

Yours is actually off the original topic (though entirely appropriate
for the newsgroup), but exactly describes my techniques over the past
15 or so seasons.

It's almost disappointing that those techniques have resulted in zero
required adjustments or repairs in over 1000 hours' operation. I do the
tests, the tests say "no problem".

The problem is that " Idle" is a relative term. I just finished
overhauling the governor for a Gardner engine 6 cylinder engine that
turned 1150 RPM at full throttle, and idled at 500 RPM. An 18 Ltr
engine producing 170 H.P. A little hard to get it up to the
recommended 1300 - 1500 RPM :-)

I also saw, but didn't work on, a single cylinder semi-diesel that ran
at 200 RPM. I asked the Motor-man how long it had been running and he
told me that he had been there for five years and it was running when
he got there and never stopped during his stay.

Somehow this dire warning not to idle a diesel doesn't seem to apply
to some engines. I think that if you substitute "lightly loaded" for
"idle" you might more accurately describe the condition.

As an aside, I have been fooling with these engines for some 50 or 60
years and the only people I have ever heard talk about not idling
diesels are boat people and primarily yacht people. Heavy trucks,
drilling rigs, heavy equipment, fishing boats, all frequently idle or
run at low power for long periods with no apparent problems.

Now I'm not trying to say that yachties don't know what they are
talking about but it does seem strange that they seem to be the only
people that talk about "not idling engines".

I suspect, but can't prove that yacht engines are seldom run at
maximum continuous horsepower settings for any length of time while
most commercial engines are. A bulldozer, for example will operate at
either idle or full throttle all its working life. Generator sets are
usually sized to work at about 90% of maximum continuous rating. I
installed a 1500 HP compressor engine that was sized to operate at 90%
of maximum. That engine, by the way, was overhauled after 5 years of
24 hour a day operation, some 40,000 hours of operation. And that
overhaul was done primarily because the plant had to be shut down to
replace some piping and the manager decided that as long as the plant
was down for a month they "might as well overhaul the engine".

My own suspicions are that if you run an engine for long periods at
light loads, as many people do when charging batteries you are asking
for problems. Particularly if you don't follow that low load period
with a period at nearly full power.

My own Perkins, overhauled 8 years ago is run at 2,000 RPM to charge
batteries and at the same RPM when motoring. Other then that I don't
pay any attention to whether it is idling or not. If I'm rigging the
mooring lines it idles. It doesn't burn any more oil today then it did
just after I overhauled it....


Bruce-in-Bangkok
(correct email address for reply)

On 2008-04-05 09:48:23 -0400, Bruce in Bangkok said:

I suspect, but can't prove that yacht engines are seldom run at maximum
continuous horsepower settings for any length of time while most
commercial engines are.

Talking around the docks, and here, I find that most 'yacht' engines
are also either at idle or 80+% of designed revs.

I'm a bit unusual that I normally power at less than 80% of the
engine's max revs to maximize fuel economy. At 70-75% of max revs, we
get 25-30 mpg. 80% has us pushing against hull speed. Full revs push us
over hull speed, and I've only done that twice in 15 seasons.

Most sailors run at high power when they motor. If they turn the motor
on, they're by definition in a hurry.

--
Jere Lull
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/

"Jere Lull" wrote in message
news:2008040520315216807-jerelull@maccom...
On 2008-04-05 09:48:23 -0400, Bruce in Bangkok
said:

I suspect, but can't prove that yacht engines are seldom run at maximum
continuous horsepower settings for any length of time while most
commercial engines are.

Talking around the docks, and here, I find that most 'yacht' engines are
also either at idle or 80+% of designed revs.

I'm a bit unusual that I normally power at less than 80% of the engine's
max revs to maximize fuel economy. At 70-75% of max revs, we get 25-30
mpg. 80% has us pushing against hull speed. Full revs push us over hull
speed, and I've only done that twice in 15 seasons.

Most sailors run at high power when they motor. If they turn the motor on,
they're by definition in a hurry.


I've noticed another prevalent reason why they start their inboard motors
even if they don't need them. They say it's to top off the batteries but I
can't help but notice it's more of a security blanket. They feel more secure
and safer if the motor is running even when they're sailing. This is
especially noticeable in rough weather. There's something about that motor
running even in idle that makes them feel better. The binky effect, so to
speak!

Even at anchor, the minute high winds or threatening dark clouds come up
many diesels began to run. They say it's to take the strain off the anchors
but that's bull****. It's to take the strain of their paranoid minds. They
don't trust their own anchoring jobs! This is a sad statement about how
motors actually cause sailors to be sloppy so they rely more on their motors
and then they become sloppier so they rely still more on their motors and
when the motor dies they are lost, totally lost. This is today's sad state
of "sailing."

Wilbur Hubbard

On Sun, 06 Apr 2008 00:31:52 GMT, Jere Lull wrote:

On 2008-04-05 09:48:23 -0400, Bruce in Bangkok said:

I suspect, but can't prove that yacht engines are seldom run at maximum
continuous horsepower settings for any length of time while most
commercial engines are.

Talking around the docks, and here, I find that most 'yacht' engines
are also either at idle or 80+% of designed revs.

I'm a bit unusual that I normally power at less than 80% of the
engine's max revs to maximize fuel economy. At 70-75% of max revs, we
get 25-30 mpg. 80% has us pushing against hull speed. Full revs push us
over hull speed, and I've only done that twice in 15 seasons.

Most sailors run at high power when they motor. If they turn the motor
on, they're by definition in a hurry.

Your engine is too big, simple as that :-) By the way, how do you
calculate miles per gallon? No tides in the Chesapeake?

Over in the dry (N.E. monsoon) season you motor when there isn't any
wind, which is usually when the land breeze dies about 11:00 every
morning.

Bruce-in-Bangkok
(correct email address for reply)

"Bruce in Bangkok" wrote in message
...
Over in the dry (N.E. monsoon) season you motor when there isn't any
wind, which is usually when the land breeze dies about 11:00 every
morning.


Yah, like you really need to motor when tied up to the dock for the past two
years. Nice try, Brucie Boi!

Wilbur Hubbard

On Sun, 06 Apr 2008 09:14:15 +0700, Bruce in Bangkok
wrote:

On Sun, 06 Apr 2008 00:31:52 GMT, Jere Lull wrote:

On 2008-04-05 09:48:23 -0400, Bruce in Bangkok said:

I suspect, but can't prove that yacht engines are seldom run at maximum
continuous horsepower settings for any length of time while most
commercial engines are.

Talking around the docks, and here, I find that most 'yacht' engines
are also either at idle or 80+% of designed revs.

I'm a bit unusual that I normally power at less than 80% of the
engine's max revs to maximize fuel economy. At 70-75% of max revs, we
get 25-30 mpg. 80% has us pushing against hull speed. Full revs push us
over hull speed, and I've only done that twice in 15 seasons.

Most sailors run at high power when they motor. If they turn the motor
on, they're by definition in a hurry.

Your engine is too big, simple as that :-) By the way, how do you
calculate miles per gallon? No tides in the Chesapeake?

Over in the dry (N.E. monsoon) season you motor when there isn't any
wind, which is usually when the land breeze dies about 11:00 every
morning.

Bruce-in-Bangkok
(correct email address for reply)


Correction: should have read "over here in the dry...." got in a
rush... Your breakfast is on the table! Yup. YOUR breakfast is on the
table! Yup. YOUR BREAKFAST IS ON THE TABLE..........



Bruce-in-Bangkok
(correct email address for reply)

On 2008-04-05 22:14:15 -0400, Bruce in Bangkok said:

On Sun, 06 Apr 2008 00:31:52 GMT, Jere Lull wrote:

On 2008-04-05 09:48:23 -0400, Bruce in Bangkok said:

I suspect, but can't prove that yacht engines are seldom run at maximum
continuous horsepower settings for any length of time while most
commercial engines are.

Talking around the docks, and here, I find that most 'yacht' engines
are also either at idle or 80+% of designed revs.

I'm a bit unusual that I normally power at less than 80% of the
engine's max revs to maximize fuel economy. At 70-75% of max revs, we
get 25-30 mpg. 80% has us pushing against hull speed. Full revs push us
over hull speed, and I've only done that twice in 15 seasons.

Most sailors run at high power when they motor. If they turn the motor
on, they're by definition in a hurry.

Your engine is too big, simple as that :-)

No disagreement, but it was an engine new to the market. Its
predecessor would have been just right, but I liked the idea of the
closed-loop fresh-water cooling.

I still prefer it, truth be told.

By the way, how do you calculate miles per gallon? No tides in the Chesapeake?

We have tides, more accurately we have currents that tend towards a
full knot southbound in our area, but I'm dividing average speed
through the water by average fuel burn. Speed over the ground will vary
with the current of course.

Over in the dry (N.E. monsoon) season you motor when there isn't any
wind, which is usually when the land breeze dies about 11:00 every
morning.

Exactly. You're in a hurry. Otherwise, you'd wait for the wind to come back.

;-)

Nothing wrong with that, since that's why we have auxiliaries, but few
sailors power much below hull speed. By dropping the speed a knot or
so, consumption drops dramatically.

If we have the auxiliary on and in gear, we pull nearly 3 knots at
idle. But our most economical speed is about 5 or 5.5 knots. Our
theoretical hull speed is 6.65 knots, though Xan is as comfortable at
7+ knots as 5 under sail.

Come to think about it, she's more comfortable above that speed than
below, but she is a known show-off that delights in breaking the rules.
She considers hull speed a suggestion, not a law.

--
Jere Lull
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/

On Sun, 06 Apr 2008 10:30:44 GMT, Jere Lull wrote:

On 2008-04-05 22:14:15 -0400, Bruce in Bangkok said:

On Sun, 06 Apr 2008 00:31:52 GMT, Jere Lull wrote:

On 2008-04-05 09:48:23 -0400, Bruce in Bangkok said:

I suspect, but can't prove that yacht engines are seldom run at maximum
continuous horsepower settings for any length of time while most
commercial engines are.

Talking around the docks, and here, I find that most 'yacht' engines
are also either at idle or 80+% of designed revs.

I'm a bit unusual that I normally power at less than 80% of the
engine's max revs to maximize fuel economy. At 70-75% of max revs, we
get 25-30 mpg. 80% has us pushing against hull speed. Full revs push us
over hull speed, and I've only done that twice in 15 seasons.

Most sailors run at high power when they motor. If they turn the motor
on, they're by definition in a hurry.

Your engine is too big, simple as that :-)

No disagreement, but it was an engine new to the market. Its
predecessor would have been just right, but I liked the idea of the
closed-loop fresh-water cooling.

I still prefer it, truth be told.

By the way, how do you calculate miles per gallon? No tides in the Chesapeake?

We have tides, more accurately we have currents that tend towards a
full knot southbound in our area, but I'm dividing average speed
through the water by average fuel burn. Speed over the ground will vary
with the current of course.

That is a legitimate method although a little depressing at times. I
was coming up the Malacca straits (with too small a prop) and
according to the Knot Log was doing 4 knots. According to the GPS, 1
knot. Not only that but my wife kept saying "when are we getting to
....., Why aren't we going faster...." Not one of my better trips.

Not only that but when I took the too small, full feathering, very
expensive, propeller off and had it for sale at a "second hand" boat
stuff shop the shop got raided by customs who declared the entire
stock as smuggled, i.e., not duty paid and my prop got confiscated.

Not a good experience at all.

Over in the dry (N.E. monsoon) season you motor when there isn't any
wind, which is usually when the land breeze dies about 11:00 every
morning.

Exactly. You're in a hurry. Otherwise, you'd wait for the wind to come back.

;-)

The wind will come back tomorrow, about 08:00, for three hours.

Nothing wrong with that, since that's why we have auxiliaries, but few
sailors power much below hull speed. By dropping the speed a knot or
so, consumption drops dramatically.

If we have the auxiliary on and in gear, we pull nearly 3 knots at
idle. But our most economical speed is about 5 or 5.5 knots. Our
theoretical hull speed is 6.65 knots, though Xan is as comfortable at
7+ knots as 5 under sail.

Come to think about it, she's more comfortable above that speed than
below, but she is a known show-off that delights in breaking the rules.
She considers hull speed a suggestion, not a law.

Do you sail with only your wife ( or significant other) or do you
have a mob aboard? I have a 40 ft. sloop and find it a fine boat for
myself and my wife but a bit small for more. Or perhaps I'm a just a
grouchy old man.

The last passenger I had aboard was a friend of a friend that had
helped the friend to bring his boat back to Thailand when the friend
was sick. As a result he didn't have the correct stamps in his
passport and I was asked to take him back to Malaysia. .

I picked the guy up at a remote island and he obviously had been
drinking beer for the better part of the day and hadn't bothered to
bathe in the past few days. As soon as he came aboard I explained that
we slept on the deck as it was too hot down below and even then my
wife birched (in Thai) for the two days we had him aboard. No more
favors for that "friend".

Bruce-in-Bangkok
(correct email address for reply)

On 2008-04-06 08:45:15 -0400, Bruce in Bangkok said:

Do you sail with only your wife ( or significant other) or do you
have a mob aboard? I have a 40 ft. sloop and find it a fine boat for
myself and my wife but a bit small for more. Or perhaps I'm a just a
grouchy old man.

We're a bit smaller, but find Xan's about right for the two of us. We
rarely take others onboard because our pleasure dome is intended for us
two. We need and enjoy the time alone.

Being a grouchy old man is disconnected with the size of boat ;-)

--
Jere Lull
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/