Diesel Fuel Flow Meter for mechanical engines data presentation and smoothing Q

[Bandit]

I looked at this for my boat with non electronic engines.

My new diesel car says what my recent average MPG is which is useful.

On a boat it needs to be measured against a speed log ie speed through the water as against SOG is useless as it measures ground covered and ignores tides. Tides where I am make a significant difference. I need to know how much fuel is likely to be used for say 10 nautical miles covered through the water with or against the tide. Ideal would be over last say 15 minutes averaged out.

A following sea withe reasonably large waves makes a huge difference on my boat 19 knots cruising rpm of 14 knots up the back of a wave and 22 to 24 knots down the face of a wave.

Its one thing knowing what you are burning in litres per mile through the water, then you need to have an accurate knowledge of how much fuel is left in each tank and then to be able to work out what your range is.

I can tell what is in each tank at any time at rest to within 10 litres per tank.

 

[vas]

thanks for all the replies/suggestions/ideas!

wont reply to each post separately, just the points made:

first installation as in all such systems is reasonably simple as you don't have to break into high pressure pipes, just fit the IN line from your ext filter/water separator/whatever you have and BEFORE the flex hose reaches the engine lift pump. So plain flex hose job.
Return similarly got to find the hose returning from the injectors back into tank and fit it between.
Actually I put the devices just above my Separs so it's easy to check for any leaks and don't need to do fancy routing of fuel hoses at least for the inlets. Return depends where your tanks are, but I guess you'll need some new pieces of hose.
Overall I'd say a few hours to fit (and they did provide with all the fittings, banjos, nuts, hose even copper washers...)

As mentioned, it does measure both in and return from the engines, different chambers, so pretty accurate as well as doing the necessary temp compensation.
Note that total fuel burnt, lpnm, nm to empty and anything else apart INSTANT FUEL CONSUMPTION in l/h is done at the MFD/plotter/gauge level, not by them h/w ppl as there's no way to pass any other info to the NMEA2000 bus.

I'm only helping as a tester (and checking NMEA2000 sentences, registration on bus etc) I'm NOT doing the programming! So each testing session means I get sent a firmware, get down in the e/r with laptop at hand, wire up, update, rehook to bus, go up check Therefore I'm just passing comments/logs/videos back to them and discuss solutions.

Smoothing issue as explained from the developers is due to the fact that they work in getting their totals right, that's not something they are willing to compromise. So at low fuel burn rates fluctuations and smoothing may get silly values. They are now trying to get a firmware that for low fuel flows it's less smoothed and there's longer sampling (smoother) for high fuel flows (as the 20kn video shows large fluctuations). Depending on pipe lengths, layout etc, you may end up at instances with 0 or negative values at v.low (idle) flows and you simply cannot have that! OTOH artificially smoothing without keeping track of real values will produce erroneous totals.
For sure the values of overall fuel burnt for the trip match sight gauges and my log from this summer trips.

Now, what am I going to do with that data, why I want one?
Help me optimise consumption is the main task, instead of having a calculator by the lower helm and thinking if we do this leg with 8.5 with this wind we'll need Xlt and arrive at Yhrs but if we go 7.5kn we'll burn 0.7X or 0.9X depends and arrive Zhrs can be done on the spot by the plotter...
Growth, seastate, wind all play their role and since I'm 99% at D speeds optimising every little bit helps especially as I'm planning some longer trips for next summer. Not sure how engine monitoring can be enhanced with fuel measurement, probably missing something there.

Regarding on how you calc consumption I guess it's up to the plotter to give you lpnm SOG or STW. I rarely see more than a knot difference due to tide/wind, so haven't checked it further. But as I said before that's plotters job not fuel monitoring h/w territory.

I'll let you know how smooth it will get soon I hope. They plan to get the system on the market as soon as we're happy with it. We being them developers and us users I'd guess before the end of the year as practically it's just the smoothing to sort out.

cheers

V.

 

[Bouba]

If anyone uses the information from the flow meter to calculate total range of the vessel then you need one for the generator as well

 

[jrudge]

If anyone uses the information from the flow meter to calculate total range of the vessel then you need one for the generator as well

Jfm tried ( succeeded?) to add this to his for that reason

Bear in mind the gen uses 4lph!

 

[Whitelighter]

Vas,

Assuming its budget boater friendly I will definitely have a set

 

[jfm]

Yours is a light over powered boat so you will probably see little change.

The throttle sets the revs only on an electronic boat. The throttle position is then managed by the ECU to keep the RPM static

A boat uses more energy to go up hill than down and the engine has to deliver more power by opening the throttle to keep the revs static ( which it does within 2-3 RPM). You can also see the boost change as it does this and the fuel flow with it.

It is also interesting that a tail wind vs a head wind makes a fair difference given these large lumps are not really that aerodynamic. Finally the difference a fouled prop makes is simply staggering.

On a manual boat then the throttles are of course directly controlling ... the throttle.

J that is correct except for the last sentence. There is no throttle on a Diesel engine. On a manual (i.e. Non electronically governed) engine the throttle lever controls the rpm setting of a mechanical rather than electronic governor.

@Vas those numbers appear much less damped than my set up which reads fuel flow from the caterpillar j1939 canbus. It's hard to believe that a range of 4.6-7lpm is correct at 20 kts, unless you were climbing big headseas that day. I see +/- 1.5 Lpm on a baseline reading of 16, at 20 knots when in a decent sea, and I see +/-0.5 or less in flat seas. I'm displaying via garmin too so any inherent damping within garmin s/w should be same as yours, and I can't see why cat would introduce damping in their part of the process. I would be suspicious about 4.6-7 readings if the sea was flat.

 

[jfm]

Jfm tried ( succeeded?) to add this to his for that reason

Bear in mind the gen uses 4lph!

yup i fitted maretron fuel flow to both gensets. I find it useful because I calculate fuel precisely and go down to 200 litres in 7000+ of tanks if it suits my itinerary/holiday. Using mby's 20% reserve makes no sense with big tanks. I can easily do 500+ litres of genset fuel in a week so it is important to know what they have consumed if you want to dice with death.

 

[jfm]

Btw and just fwiw for those in tidal waters, the garmin lpm calculation is selectable iirc to compute off STW or SOG. I'm non tidal so I use SOG.

 

[vas]

Vas,

Assuming its budget boater friendly I will definitely have a set

Jez,
will let you know once they are ready, mind you have to get a NMEA2000 compatible display that supports certain sentences PGNwhatever (don't remember now off hand, will post later if you wish) for them. Have you got something? Else you have to count that in as well...

@Vas those numbers appear much less damped than my set up which reads fuel flow from the caterpillar j1939 canbus. It's hard to believe that a range of 4.6-7lpm is correct at 20 kts, unless you were climbing big headseas that day. I see +/- 1.5 Lpm on a baseline reading of 16, at 20 knots when in a decent sea, and I see +/-0.5 or less in flat seas. I'm displaying via garmin too so any inherent damping within garmin s/w should be same as yours, and I can't see why cat would introduce damping in their part of the process. I would be suspicious about 4.6-7 readings if the sea was flat.

Sea was flat, not glass flat but maybe a F1-2
Hence me asking.
So I'll just tell them that we should be aiming at +-.5 on flat seas and let them find how to do it.
Not sure how they do their calcs and how fast their processors and calcs are, but for sure the totals are right. I guess since they never had a realtime screen but just worked on totals their s/w will need a bit of a re-write to get up to our needs, nothing serious though. Will let you know how it develops.

Btw and just fwiw for those in tidal waters, the garmin lpm calculation is selectable iirc to compute off STW or SOG. I'm non tidal so I use SOG.

correct, same thing is valid for apparent wind as I found out last week, since apparent and true were the same and I realised that speed calcs for it were set by default to AUTO which meant DST800 speed through water (with a stuck wheel...) Changed that to GPS speed all's fine. Not for tidal waters though.

cheers

V.

 

[MapisM]

So I'll just tell them that we should be aiming at +-.5 on flat seas and let them find how to do it.
Not sure how they do their calcs and how fast their processors and calcs are, but for sure the totals are right.

V, as I understand it, jfm point is not about how to elaborate the numbers, but about their actual reliability - and fwiw, I would tend to agree.
I mean, if you read anywhere from 4.6 to 7 lpm, it can only be because the fuel sensors are actually "reading" such different numbers (smoothing algorithm, if any, being done by definition ex-post, so to speak).
But if the sensors read those numbers in practically flat conditions, the numbers themselves are bound to be wrong to some extent, because there's no way that the actual fuel burn can oscillate that much.
Otoh, if you are sure that totals are correct over a meaningfully long period of time, I take your word for it.
But it's sort of weird that such big oscillations at highly granular level of measurement are not affecting also the reliability of totals, if you see what I mean...

 

[jfm]

V, as I understand it, jfm point is not about how to elaborate the numbers, but about their actual reliability - and fwiw, I would tend to agree.
I mean, if you read anywhere from 4.6 to 7 lpm, it can only be because the fuel sensors are actually "reading" such different numbers (smoothing algorithm, if any, being done by definition ex-post, so to speak).
But if the sensors read those numbers in practically flat conditions, the numbers themselves are bound to be wrong to some extent, because there's no way that the actual fuel burn can oscillate that much.
Otoh, if you are sure that totals are correct over a meaningfully long period of time, I take your word for it.
But it's sort of weird that such big oscillations at highly granular level of measurement are not affecting also the reliability of totals, if you see what I mean...

Yes, exactly. The granular data is highly questionable in my view. It may be that the error is sufficiently random that you get equal + error as -error, in which case the total fuel burn over an hour is ok. In which case they should just smooth/average the data.

I wonder also if their flow measuring equipment is very good but you have pulsing in your fuel-in hoses, due to the mechanism of your primary fuel pump. That feels entirely possible and if the pulsating is sinusoidal then in theory the errors in the “snapshot” flow readings would average out to zero over time, hence again your accurate readings over an hour. solution again is to ask them to smooth the data in their software.

 

[gjgm]

Perhaps before they go too far,they should try this in another boat/engine set up for comparison, rather than base the next dev. on a single set up?

 

[Lon nan Gruagach]

Sounds like a similar problem to audio metering...
Have a look at https://www.soundonsound.com/sound-advice/q-whats-difference-between-ppm-and-vu-meters especially the last paragraph regarding decay rate.

I've not looked at the new standard (still living in the past me) but generally the audio is sampled, short duration averaged and then that value is smoothed, in the case of PPM the reading will increase quickly, but decay slowly.

 

[GrahamHR]

When I took a powerful torch and a big magnifying glass to look at the display in my EVC-C tachometer and got very close to it I was amazed at the data available, My boat seems to have the fuel computer upgrade; I didn't know.

However, I can see none of this information whilst underway as the display is small and not very bright even at the maximum brightness setting. Anyone bought/ fitted that VP interface that allows the useful information to be readable on a tablet etc ; does it work ?

 

[Marlinmarty]

hello all,

a few years ago I started searching for cheaper/diy alternatives to Maretron regarding fuel flow monitoring.
After many setbacks, I ended up helping a company doing diesel fuel monitors for trucks open up to the marine market.
I hadn't realised that fuel monitoring in HGV is such a big business. (I guess mainly to help logistics companies sort out diesel costs and not be stung by drivers?)

Anyway, got two 250lph devices foc for testing and feedback. Each one is two separate measuring chambers with in and outs with a common electronic unit on top with NMEA2K cabling. Similar to Maretron and apparently v.accurate as well.

So to cut a longish story sort, and after 3-4 incarnations of the s/w in order to properly sent the right NMEA2000 sentences, identify port/sbrd engine, etc, I now have decent fuel flow data for both engines. Garmin (and all others that support fuel flow data) does some lt per nm calcs as well which are really helpful.
Following are three videos I took on Sunday evening coming back to port on flat seas, with a bit of growth at the places I've not put proper coppercoat this year (will do in spring), with trim tabs not functioning as in extending fully, and clean props (which really impresses me after almost 4months in the water, but I'll do another thread on that later). Also note that GPS vs Autopilot heading is almost 30degrees off (when going Northish, but spot on when going Southish...), need to do the a/p config thing again (turning around in flat seas etc).
Fins were parked in the middle and slightly offset in most videos (was mainly playing with them, but will do more testing during the next couple of weeks)

Now what I'd like your opinion is if you feel that the values reported should need any further smoothing. The guys doing this h/w never bothered with presenting the data realtime as it's basically a logger. So they are happy to do the calcs (and they are indeed accurate!) but not so sure how much to smooth the data.

Note smoothing or not, wont affect the overall values logged/reported and hence the overall trip fuel values.
Note2 during these videos, I had already been travelling on that speed for at least a couple of mins before taking the shot so flow and return was theoretically settled on the conditions...

(only two embedded videos allowed apparently, so third just a link to youtube)

there's another one at 6.5kn burning 1.1lpnm or so and I somehow missed my favourite speed of 7.5kn but not much point boring you to death...

so, should they smooth a bit more, or not?
If you do have fuel monitors how stable are the values? I'd guess that ECU based monitoring would be more stable, not sure on mech. engine ones though!

cheers

V.

PS. I personally think they should smooth them more

Hi Vas
Whatever happened to this product did it go to market. Quite interested
I am in NZ navman had this years ago but brunswick and navico killed it off.