Minnimum Cummins cruising spedd
 

Yes, calling cummins is by far the best thing because your questions
answer can only be found knowing all the specs of *your* boat and the
conditions you are moving through.

Minnimum Cummins cruising spedd
 

Let's say you just took delivery of a used 27000# trawler powered by a
single Cummins turbo-diesel 220, model 6BT5.9M. You want to get maximum
miles per gallon out of it and know the slower you go, the better, but
these motors don't like to go slow for a number of reasons. Of course,
you also want it to last forever because it might cost $10,000 to
rebuild it, not including pulling it out and putting it back in..

What would you consider a minimum cruising speed, with an occasional
shot at 2000 rpm just to clean things out?

Capt. Jeff

Minnimum Cummins cruising spedd
 

Tamaroak wrote in news:Fd2dnbJAg-bp2pbZRVn-
:

these motors don't like to go slow for a number of reasons

Huh?? Where'd you hear this nonsense? A diesel doesn't like to go slow?

What reasons do you know about to go with this??

A friend, who should never have been allowed to drive a 56' Hatteras away
from the dock, ran its twin 8V92TA, twin turbocharged train engines at idle
for many years before I came along. I must admit there was a "little
carbon" in the waterboxes that came out when I "opened 'er up" offshore of
Charleston. It looked something like a ship blowing the boilers..(c;

These idled-for-years old Detroit Diesels had ONE little weak injector
spring in one engine when the diesel shop pulled them all apart for
inspection for the massive survey the buyer paid for when he sold it. ONE
spring! To start them, you simply flipped the switch to ON and barely
touched the start button and they jumped to life, even stone cold.

I don't believe Dan hurt them treating these beasts like the boat was a
trawler all those years he owned it.

Sure made a big cloud of carbon (cough)(cough)(choke)(gasp) 5 miles
offshore...(c; I told him I was trying to hide the brown trail he was
leaving when the mascerator pump was emptying those massive dirty tanks...
(c;

Minnimum Cummins cruising spedd
 

Tamaroak wrote

these motors don't like to go slow for a number of reasons

Larry wrote:

Huh?? Where'd you hear this nonsense? A diesel doesn't like to go slow?

What reasons do you know about to go with this??


Suggest you check out "wet stacking".

Usually requires and idle RPM around 1,400 RPM to prevent.

Lew

Minnimum Cummins cruising spedd
 

On Sun, 05 Mar 2006 22:59:31 -0500, Larry wrote:

What about my diesel cars that hardly ever leave the city? I've never seen
this phenomenon while sitting in the traffic for hours on end, idling along
to the next traffic light.....??

Maybe it isn't as serious as it's imagined.....??

The problem as I understand it, is particularly acute for turbo
engines. If the turbo does not get spun up to speed and temperature
on a fairly regular basis, it will carbon up and require big $$$s to
fix. When I was shopping for a new diesel genset 2 years ago I
avoided all turbo engine options for exactly that reason.

In a diesel car, particularly an underpowered car like a Mercedes 220,
you will almost surely do enough hard accelerating to avoid wet
stacking.

Minnimum Cummins cruising spedd
 

Larry wrote:
Larry wrote in
:


I could see it would carbon up if you just ran the engines in an
unloaded condition in neutral for long periods of time....


Thinking about this, I cannot help but think about those engines in the big
trucks that are left idling for 8 hours, virtually unloaded, while the
driver is sleeping in his sleeper at the truck stop. I suppose he burns
off all the deposits when he drives off down the interstate in the morning.

You need to develop enough reject heat to keep the cylinder walls hot
enough to prevent wet stacking.

The spec I always seen is to idle somewhere between 1,300-1,500 RPM,
depending on engine.

Lew

Minnimum Cummins cruising spedd
 

On Mon, 06 Mar 2006 15:46:46 GMT, Don W
wrote:

In
the vending business our diesels would probably accrue 2000+ hours
per year.

How was their reliability longevity?

Minnimum Cummins cruising spedd
 

In article t,
Lew Hodgett wrote:

Larry wrote:
Larry wrote in
:


I could see it would carbon up if you just ran the engines in an
unloaded condition in neutral for long periods of time....


Thinking about this, I cannot help but think about those engines in the big
trucks that are left idling for 8 hours, virtually unloaded, while the
driver is sleeping in his sleeper at the truck stop. I suppose he burns
off all the deposits when he drives off down the interstate in the morning.

You need to develop enough reject heat to keep the cylinder walls hot
enough to prevent wet stacking.

The spec I always seen is to idle somewhere between 1,300-1,500 RPM,
depending on engine.

Lew

the above, is really not the problem. The real problem is running a
diesel engine below operating temps, for extended periods (months)
of time, with no at operating temps operation. If the engine is
operated below operating temp, carbon will tend to build up on
combustion path surfaces, and it will not be removed, or burnt off,
by normal temp operation. This is aggrivated in exhaust driven turo
systems, because the Exhaust Side turbo also isn't running at designed
temp and will accumulate excess carbon buildup.

This whole "WetStacking" business is more a minor problem of operational
terminology, that an actual mechanical problem that needs alternate
operational techniques to solve.

If the engine is running at designed temps, with the thermostat in the
open condition, usually will allleviate and excessive carbon buildup.
Any operation with loads of 25% or more of rated HP, for more than 10%
of total operational hours, will be more than enough to deal with an
preceived problems of this nature for Normally asperated diesel engines.
For a exhaust powered turbo diesel, if your exhaust side turbo is
running at operational temp, your fine, no matter what the cooling
system is doing, and that will usually be at somewhere around 10
to 15% of rated HP, loading.

All this is variable, depending on the engineering of the engine design,
and most OEM's will have a Spec published for minimum ehgine operational
temps and loadings for extended operational times.

Me

Minnimum Cummins cruising spedd
 

Hi Wayne,

Wayne.B wrote:
On Mon, 06 Mar 2006 15:46:46 GMT, Don W
wrote:


In
the vending business our diesels would probably accrue 2000+ hours
per year.


How was their reliability longevity?

We had really good reliability with the Cummins. The problems
we had were mostly related to fuel / fuel filters, etc. The engines
themselves were fine.

As far as longevity, I can only comment out to ~4000 hours, because
I sold the business after two years. During that two-year period
we did not have to rebuild an engine or turbo, and at the end the
vehicles were all in good running condition.

OTOH, we only got about 8MPG on the vans, and when I sold the business
diesel had become more expensive than gasoline! :-( It is very strange
to me to see diesel selling at a premium, because it has been much
cheaper over most of the last 40 years, and is a lower grade product
IIRC.

Don W.

Minnimum Cummins cruising spedd
 

Don W wrote:

Is "wet stacking" a problem that is unique to boats?


Not really.

Wet stacking happens when the engine system does not come up to
operating temperatures for extended periods.

If the engine is allowed to idle around 1,500 RPM, sufficient reject
heat is generated to eliminate the problem.

Lew

Minnimum Cummins cruising spedd
 

On Mon, 06 Mar 2006 21:01:33 GMT, Lew Hodgett
wrote:

Wet stacking happens when the engine system does not come up to
operating temperatures for extended periods.

This talk about not coming up to operating temperature has me mildly
confused. Isn't that what the thermostat is for? My diesels will
come up to thermostat temperature at slow idle with no load at all.

What am I missing?

Minnimum Cummins cruising spedd
 

Wayne.B wrote:


This talk about not coming up to operating temperature has me mildly
confused. Isn't that what the thermostat is for? My diesels will
come up to thermostat temperature at slow idle with no load at all.

What am I missing?


Don't think you are probably missing anything.

A diesel will idle at relatively low RPM.

This low RPM may not allow the engine to come up to operating
temperature(with or without a thermostat).

Result is incomplete combustion which will allow unburned fuel to glaze
onto cylinder walls.

The result of that is a very expensive repair bill.

Lew

Minnimum Cummins cruising spedd
 

Have a search at www.boatdiesel.com, this has been covered many times.
There is also an article on this:
http://boatdiesel.com/Articles/Artic...ion.cfm&Y=2004

You will need to join the web site to read this one, ($25/yr, and
worth it every once and a while).

I to have a 6B in a trawler and have am OK with slow operation. My
normal cruise is 1400 rpm (6.7kn). Key here is to get the motor to
operating temperature (Idling, even at a fast idle will not do it, you
need to run the boat) and then make sure it stays at temp.

The 6B's at times have problems with their thermostats, so watch that
and if the temp falls off, then change it out 1st thing. I had to
change out mine at 400hrs, no problems after doing so.

When we run Christmas ships I spend a few hours at a time at 1100-1200
RPM, and the temp always stays up. So, again, the key here is get up
to temp (I usually run around 1700 or so to make sure I am up to temp)
and do not worry. Based on what I have seen from people who have been
around motors with high hours, I am expecting well over 10,000hrs on
my motor. Turbo included

-al-

On Sun, 05 Mar 2006 14:17:33 -0800, Tamaroak
wrote:

Let's say you just took delivery of a used 27000# trawler powered by a
single Cummins turbo-diesel 220, model 6BT5.9M. You want to get maximum
miles per gallon out of it and know the slower you go, the better, but
these motors don't like to go slow for a number of reasons. Of course,
you also want it to last forever because it might cost $10,000 to
rebuild it, not including pulling it out and putting it back in..

What would you consider a minimum cruising speed, with an occasional
shot at 2000 rpm just to clean things out?

Capt. Jeff

Minnimum Cummins cruising spedd
 

On Sun, 05 Mar 2006 22:59:31 -0500, Larry wrote:

Larry wrote in
:

I could see it would carbon up if you just ran the engines in an
unloaded condition in neutral for long periods of time....

Thinking about this, I cannot help but think about those engines in the
big trucks that are left idling for 8 hours, virtually unloaded, while
the driver is sleeping in his sleeper at the truck stop. I suppose he
burns off all the deposits when he drives off down the interstate in the
morning.

Obviously, 8 hours of idling while sleeping, followed by 8 hours of 80
mph under load, followed by 8 hours of idling, again, isn't hurting
Cummins engines much. Hell, they don't overhaul them in the real world
away from the service manual until the clock says 400,000 to 500,000
miles...or more.

What about my diesel cars that hardly ever leave the city? I've never
seen this phenomenon while sitting in the traffic for hours on end,
idling along to the next traffic light.....??

Maybe it isn't as serious as it's imagined.....?? My 73 220D was
overhauled at 300K after 28 years on the road. Its exhaust always
looked black and oily, especially if you brushed your pants against the
pipe getting the load out of the trunk. I saved a piston and the valves
from the overhaul junk pile. There wasn't any kind of hard coked
deposits anywhere you couldn't wipe off with a shop rag....

Automotive/truck diesels are different, designed to run at light load for
extended periods. Marine/industrial diesels are designed to run at high
load all the time, like a truck pulling a full load over an endless
mountain pass. Of course there's some crossover, but for the most part
these are different types of engines.

Matt O.

Minnimum Cummins cruising spedd
 

"Matt O'Toole" wrote in message
g...
On Sun, 05 Mar 2006 22:59:31 -0500, Larry wrote:
Automotive/truck diesels are different, designed to run at light load for
extended periods. Marine/industrial diesels are designed to run at high
load all the time, like a truck pulling a full load over an endless
mountain pass. Of course there's some crossover, but for the most part
these are different types of engines.


I suspect that many here have visited this site; for those who haven't, take
a look at this for one person's opinions on diesel power for boats (and many
other subjects).
http://www.yachtsurvey.com/GasNdiesel.htm

Minnimum Cummins cruising spedd
 

That's probably why we didn't have any problem with the
route vehicles. The 5-10 minute drive to the next stop
made sure that the engine stayed up at operating temp.

Don W.

Lew Hodgett wrote:
Wayne.B wrote:


This talk about not coming up to operating temperature has me mildly
confused. Isn't that what the thermostat is for? My diesels will
come up to thermostat temperature at slow idle with no load at all.

What am I missing?


Don't think you are probably missing anything.

A diesel will idle at relatively low RPM.

This low RPM may not allow the engine to come up to operating
temperature(with or without a thermostat).

Result is incomplete combustion which will allow unburned fuel to glaze
onto cylinder walls.

The result of that is a very expensive repair bill.

Lew

Minnimum Cummins cruising spedd
 

In article ,
Matt O'Toole wrote:

Automotive/truck diesels are different, designed to run at light load for
extended periods. Marine/industrial diesels are designed to run at high
load all the time, like a truck pulling a full load over an endless
mountain pass. Of course there's some crossover, but for the most part
these are different types of engines.

Matt O.

I really don't know where you learned your Diesel Engineering, but
a 3408 CAT is a 3408 CAT, and it really doesn't matter if it is in a
truck, boat, or Genset. The only real difference is in the governer
and not really much difference there, either.....

Me

Minnimum Cummins cruising spedd
 

"Al Thomason" wrote in message
...

When we run Christmas ships I spend a few hours at a time at 1100-1200
RPM, and the temp always stays up.

Al, please excuse my ignorance,

What is a "Christmas" ship?

RCE

Minnimum Cummins cruising spedd
 

Matt O'Toole wrote in
g:

Automotive/truck diesels are different, designed to run at light load for
extended periods. Marine/industrial diesels are designed to run at high
load all the time, like a truck pulling a full load over an endless
mountain pass. Of course there's some crossover, but for the most part
these are different types of engines.

Matt O.



Hmm...that's odd. Other than the seawater pump and heat exchanger the
Perkins 4-108 in the ketch looks exactly like the Perkins 4-108 in English
tractors! The parts even fit!

Minnimum Cummins cruising spedd
 

Me wrote in news:Me-AE1290.10191707032006
@netnews.worldnet.att.net:

I really don't know where you learned your Diesel Engineering, but
a 3408 CAT is a 3408 CAT, and it really doesn't matter if it is in a
truck, boat, or Genset. The only real difference is in the governer
and not really much difference there, either.....

Me


I thought if you connected it to a marine transmission the price
doubled....(c;

Minnimum Cummins cruising spedd
 

"Larry" wrote in message
...
Matt O'Toole wrote in
g:

Hmm...that's odd. Other than the seawater pump and heat exchanger the
Perkins 4-108 in the ketch looks exactly like the Perkins 4-108 in English
tractors! The parts even fit!

I was told, on a different series of engine, that the camshafts and valve
timing were different for a constant speed marine engine as compared to the
road engines.

Leanne