TWL: Fuel metering
<<I want to add a fuel metering system.
I never know exactly how much fuel I have burned on a particular run.
I would like to add a metering system whereby I can tell how much fuel I have
burned in each engine.
A simple fuel-flow meter won't do, since not all the fuel is burned.
I would like the meters to be mechanical, plumbed to the fuel system in the
engine room with no electronics/electrics involved, sort of like the meters on
the pumps when you fuel up.>>
Well, you could install Flowscan meters on each engine but that would cost
quite a few bucks more than wooden dip sticks. If a fuel consumption reading
with a probable error within 10% would do, you might consider putting engine hour
meters on each engine. This takes advantage of the fact that most trawler
owners spend approximately 80% of the engine on time at "cruising" speed.
Generators too operate within a narrow speed range. A simple chart relating fuel
consumption to hours of engine useage would give you a reasonably accurate measure.
On my Willard, there is no factory installed fuel measurement system. Even
the manual suggests using a dip stick. Still, by keeping track of engine hours,
we can estimate the fuel useage within a 10% range without trouble.
Larry Z
Quoting LRZeitlin@aol.com:
Well, you could install Flowscan meters on each engine but that would cost
quite a few bucks more than wooden dip sticks. If a fuel consumption reading
with a probable error within 10% would do, you might consider putting engine
hour
meters on each engine. This takes advantage of the fact that most trawler
owners spend approximately 80% of the engine on time at "cruising" speed.
Generators too operate within a narrow speed range. A simple chart relating
fuel
consumption to hours of engine useage would give you a reasonably accurate
measure.
We have engine hour meters on each engine. Running an inlet against the tide,
running up to 2200 rpm's just to maintain way at times, and stay on the range,
is far different than running offshore at a constant 1800 rpms.
Also, the "engine hour meters" start counting when the "ignition key" is in the
on position, whether or not the engine is actually running; something I also
need to fix even if this behaviour is not "broken".
I have OFTEN forgotten to turn off the "KEY" while at anchor for several days as
well; cranking up the engine hours while the engine was off!! :-((
Also, the only way to get the pilothouse wipers to function is to turn on the
KEY, cranking the engine hours up. I have found that engine houre are a totally
mythical number, and has given me no end of grief. I use those hours to do oil
changes ONLY! This is another "fault" I need to fix on Tamara B! Engine hours
should be driven from the output of the alternator, and not from the battery as
they are currently. This is something I am designing, as it is not as simple as
it seems. The engine kill-solenoide is also tied into the "key" switch and this
should be off the battery system, and not off the alternator only......
It was a riot once.... after purging air from the main engine I scream...
admiral shut it off!!! shut it off!!!! (after I got it started) she turned off
the key.... engine would not shut down!!!! I ran to the bridge and the "OFF"
would not shut it down; so I stuffed pillows into the air intake, and killed the
thing, only to find that the "key" WAS OFF!!! This should NOT be!!! Whoever
wired this boat was not operating with a full deck of cards!!!
On my Willard, there is no factory installed fuel measurement system. Even
the manual suggests using a dip stick. Still, by keeping track of engine
hours,
we can estimate the fuel useage within a 10% range without trouble.
I have been fooled by dip-stick readings.... we carry 250 gallons of fresh water
on Tamara B; all on the port side. Water consumption affects the boats list, and
thereby alters the dip-stick readings on the fuel tanks.
We are planning a trip to Ireland next summer, it will be critical to know
exactly how much fuel I have onboard, and 10% will be the safety margin... this
is why I am leaning towards a seperate fuel meter on both engine feeds and both
returns.... 10% ain't good enough; I need to know exactly how much deisel I
have, and where it is. My trouble is in finding an accurate MECHANICAL flow
meter. I will look at flowscan, hopefully it is a mechanical meter, if so, and
if the specs guarentee a reasonable accuracy, this is what I may install on all
4 lines.
I ain't had this much fun since I was a kid, but this dock-life is BOREING!!! :-)))
Regards
Bob
--
Bob & Kelly
M/V Tamara B
http://www.tamara-b.org
Bob wrote:
the "engine hour meters" start counting when the "ignition key" is in the
on position, whether or not the engine is actually running;
snip<<
Also, the only way to get the pilothouse wipers to function is to turn on the
KEY, cranking the engine hours up. >>> snip<<<
Engine hours should be driven from the output of the alternator, and not from
the battery as
they are currently. This is something I am designing, as it is not as simple as
it seems. The engine kill-solenoide is also tied into the "key" switch and this
should be off the battery system, and not off the alternator only....
snip<<<
REPLY
Bob has fallen victim to a very common practice.
Quite often the only "hot" wire found at the console is the battery feed for the
ignition switch.
A lot of installers would tie into this circuit for powering all sorts of
other equipment that was operated from the helm or only when they assumed the
engine would be turning.
The alternative of running a completely new cable from the battery to the helm
often involves several hours of effort to fish the wire past obstacles from one
point to the other.
However if you do run a pair of heavy cables capable of handling 100 amps from
battery to helm you now have a completely separate bus bar to power any number
of circuits. As long as proper circuit protection is observed, this is the safe
and proper way to do it.
Concerning hour meters. They are a maintenance item and as such can just as
well be located next to the engine not at the helm.
The same oil pressure switch that powers up the alternator can be used to power
the hour meter.
In this way the meter only runs when the engine is actually turning.
Powering the hour meter from the alternator output will not always work as
expected.
Lacking a blocking diode the meter would never shut off. and if a blocking diode
is used the meter might still quit counting when the three stage regulator cuts
back after the float stage has been reached and the alternator output goes to
zero.
Regards
Arild
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On my Willard, there is no factory installed fuel measurement system. Even
the manual suggests using a dip stick. Still, by keeping track of engine
hours,
we can estimate the fuel useage within a 10% range without trouble.
Larry Z
You're right Larry!
Just a bit of time cruising at optimum engine speeds (yes, I meant speeds)
lets you get a pretty accurate handle on fuel usage.
I know within a very fine margin my consumption at 2000, 2100 2200 and 2400
RPM (5.9, 6.1, 6.5 and 6.9kts) without a flow-meter. And I've worked it out
with an hour meter, dipstick and sight gauges.
Wasn't it your Mr Thoreau who said "simplify, simplify"?
Cheers
Glenn
"Stirling" Universal 41
Port Phillip, Australia.
If you can shut down the engine and leave the key on how are your low oil
press/high water temp alarms wired? Normally the low oil pressure alarm
will activate when the engine is shut down, and when starting of course.
-----Original Message-----
From: trawler-world-list-bounces@lists.samurai.com
[mailto:trawler-world-list-bounces@lists.samurai.com]On Behalf Of Bob
Sent: Friday, August 01, 2003 7:15 PM
To: LRZeitlin@aol.com
Cc: trawler-world-list@lists.samurai.com
Subject: Re: TWL: Fuel metering
Quoting LRZeitlin@aol.com:
Well, you could install Flowscan meters on each engine but that would cost
quite a few bucks more than wooden dip sticks. If a fuel consumption
reading
with a probable error within 10% would do, you might consider putting
engine
hour
meters on each engine. This takes advantage of the fact that most trawler
owners spend approximately 80% of the engine on time at "cruising" speed.
Generators too operate within a narrow speed range. A simple chart
relating
fuel
consumption to hours of engine useage would give you a reasonably accurate
measure.
We have engine hour meters on each engine. Running an inlet against the
tide,
running up to 2200 rpm's just to maintain way at times, and stay on the
range,
is far different than running offshore at a constant 1800 rpms.
Also, the "engine hour meters" start counting when the "ignition key" is in
the
on position, whether or not the engine is actually running; something I also
need to fix even if this behaviour is not "broken".
I have OFTEN forgotten to turn off the "KEY" while at anchor for several
days as
well; cranking up the engine hours while the engine was off!! :-((
Also, the only way to get the pilothouse wipers to function is to turn on
the
KEY, cranking the engine hours up. I have found that engine houre are a
totally
mythical number, and has given me no end of grief. I use those hours to do
oil
changes ONLY! This is another "fault" I need to fix on Tamara B! Engine
hours
should be driven from the output of the alternator, and not from the battery
as
they are currently. This is something I am designing, as it is not as simple
as
it seems. The engine kill-solenoide is also tied into the "key" switch and
this
should be off the battery system, and not off the alternator only......
It was a riot once.... after purging air from the main engine I scream...
admiral shut it off!!! shut it off!!!! (after I got it started) she turned
off
the key.... engine would not shut down!!!! I ran to the bridge and the "OFF"
would not shut it down; so I stuffed pillows into the air intake, and killed
the
thing, only to find that the "key" WAS OFF!!! This should NOT be!!! Whoever
wired this boat was not operating with a full deck of cards!!!
On my Willard, there is no factory installed fuel measurement system. Even
the manual suggests using a dip stick. Still, by keeping track of engine
hours,
we can estimate the fuel useage within a 10% range without trouble.
I have been fooled by dip-stick readings.... we carry 250 gallons of fresh
water
on Tamara B; all on the port side. Water consumption affects the boats list,
and
thereby alters the dip-stick readings on the fuel tanks.
We are planning a trip to Ireland next summer, it will be critical to know
exactly how much fuel I have onboard, and 10% will be the safety margin...
this
is why I am leaning towards a seperate fuel meter on both engine feeds and
both
returns.... 10% ain't good enough; I need to know exactly how much deisel I
have, and where it is. My trouble is in finding an accurate MECHANICAL flow
meter. I will look at flowscan, hopefully it is a mechanical meter, if so,
and
if the specs guarentee a reasonable accuracy, this is what I may install on
all
4 lines.
I ain't had this much fun since I was a kid, but this dock-life is
BOREING!!! :-)))
Regards
Bob
--
Bob & Kelly
M/V Tamara B
http://www.tamara-b.org
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Quoting Brent Trathen brent@fidalgo.net:
If you can shut down the engine and leave the key on how are your low oil
press/high water temp alarms wired? Normally the low oil pressure alarm
will activate when the engine is shut down, and when starting of course.
Ahhhhh..... the alarm panel has an "off" switch. Our 11 pound main coon cat
onboard has trained me to SHUT OFF the alarm panal just prior to hitting the
kill button on the engine. She will attack me and draw blood if she hears the
alarms go off :-((
Of course, this has trained me to start with the alarms turned ofF and after
start, turn the pannel on (the noise is absolutely awfull).
This however is the answer to the engine hour meter conundrum... the engin hours
will be re-wired to a function of oil pressure, the prescence of oil pressure
will indicate the engine is running, and will run the hours meter. This was
sugested in private mail from several list members, and seems to be the easiest
to implement. This also reduces the "ignition key" to activating the starter
solinoid only, as a simple security device.
On the fuel tank levels /fuel burn I am still at a quandry. It seems easiest to
accurately meter fuel use/return per tank with 4 flowscan units, but I LOVE the
Idea of installing sight gauges (KISS). Problem with this approach is the
non-symeterical nature of my fuel tanks. I would have the same problem as I have
with the dip-sticks. One inch of fuel at the top of a tank translates to an
entirely different "gallons" as an inch at the mid-section or lower on the tanks.
I guess one of the benefits of being tied up to a dock is the ability/time to
figure these thngs out. We got swans here, and cormorants, and ducks! No
dolphins since cape henry, but it's more life than I expected in New York, and
at $400/mO I can't/won't complain too much :-)) Guess I ain't a city-kid
anymore! These last 10 months have profoundly changed my mindset, and my life :-))
Best Regards
Bob
--
Bob & Kelly
M/V Tamara B
http://www.tamara-b.org
On the fuel tank levels /fuel burn I am still at a quandry. It seems
easiest to
accurately meter fuel use/return per tank with 4 flowscan units, but I
LOVE the
Idea of installing sight gauges (KISS). Problem with this approach is the
non-symeterical nature of my fuel tanks. I would have the same problem as
I have
with the dip-sticks. One inch of fuel at the top of a tank translates to
an
entirely different "gallons" as an inch at the mid-section or lower on the
tanks.
Hi Bob.
Re sight guages: you fill the tanks one at a time, marking each individual
gauge as you go...or at least that's what I did.
Works fine for me.
Cheers
Glenn
Re sight guages: you fill the tanks one at a time, marking each individual
gauge as you go...
Just to expand a little bit on what Glenn has said, once you have the site
gauges installed, start with an empty tank. Dispense fuel into the tank
slowly. You will need help with this as one person will have to dispense
the fuel and one person will have to watch the site glass at the tank. Have
them stop filling at 25 gallons (or 20, or 10, or whatever you choose). If
you can see the level in the glass, then mark it. Now have them put in
another 25 gallons (or 20, or 10, or whatever you choose) and mark it. Keep
going until the tank is full. Now you have an accurate gauge of how much
fuel is in the tank.
Any time we leave the dock the fuel in the tanks is recorded as part of our
check list so I can keep tabs on how much fuel is being used after a run.
Andy
Andy & Linda Woods
Grand Folly
1970 Grand Banks 36 Classic
Georgetown, MD
grandfolly@hotmail.com