Fuel Flow Meter

[Peartreetim]

Hi All, a couple of RIBs back i had a Navman which had a really handy function that i could add fuel to and the system told me how much was left at any time. I have an under deck tank on my Delta which holds 295L and i would love to find an instrument like the F210. Does anyone know of one on the market ?

[steve-ribnet]

This site's content is perhaps a little blunt, but has the information that you require:
http://www.giyf.com

I'm not that blunt, so here is some info:

I have a lowrance HDS range plotter/sounder that does this (HDS 5m gen2)

it has a fuel flow sender model "EP-60r" which sends the fuel flow rate via NMEA2000 to the plotter or other NmEA2000 fuel flow gauge. You tell the plotter how big your tank is, and when you fill it up (either all the way or just how much you add) and it displays various fuel related thinks like a virtual level, consumption rate, range etc
Garmin do one called the GFS 10 sensor, which communicates via NMEA2000 or their CANnet interface. You would plug this into a suitable plotter/display unit.

Some modern engines have a flow sensor built in to the engine that can output flow rate onto a NMeA or proprietary data bus

There are also liquid level sensors that are fuel compatible. For example the lowrance EP-65r .These output a level value (full to empty) via NmeA2000 which will display a tank level gauge on your plotter that you can calibrate to a volume of fuel, but are not accurate enough to determine fuel flow rate

A level sensor in conjunction with a fuel flow rate sensor is an ideal combination; the flow sensor is perhaps 10% accurate, and if you just do a partial tank top up each time then these errors will compound to give you a false level reading if used on its own ( filling to the brim effectively re-calibrates the level).
Combine the level and flow sensor together and you will know if you have a leak or other loss from the system unaccounted for by the flow rate, and whether the flow meter errors are adding up, necessitating a full-top up .

[Chris]

You have to go NMEA now so a lowrance LMF 400 and a fuel flow sensor. Problem is it's expensive and you are talking about £300-400 all in.

[Pikey Dave]

inline fuel flow sensors are notoriously inaccurate, especially at low speeds.

[Jeff]

Expensive ,,,, but very accurate and well made. I've had (the same) one for 14 years
( when the £:$ was MUCH better )

Flow meter and totaliser

http://www.floscan.com/html/blue/ser...ail.php?sid=16

[Into The Blue]

Got to agree, Floscan meters are very good. I use it almost as much as the rev counter.
UK dealer is Merlin in Poole, but be prepared for a big bill

[Daniel]

3rd for the floscan. Fantastic kit wouldn't want to be without really.

[Jeff]

Even with shipping and VAT these are probably cheaper than UK sourced. Remember you want the metric version ( as opposed to Galls >> US galls!)
USPS are usually the lowest shipping

https://www.dbmarine.com/sales/produ....asp?M=Floscan

[jyasaki]

Originally Posted by Pikey Dave

inline fuel flow sensors are notoriously inaccurate, especially at low speeds.

Level sensors are worse, especially in swell, and differing attack angles.

To be honest, I was pretty surprised at how accurate my Lowrance EP-60 was.

jky

[9D280]

I don't have a fuel flow, but can add a "+1" to the other Lowrance NMEA2000 sensors - I have cyl head temp & coolant pressure on my plotter.

I did look into this - I think the trick generally is getting one matched to your flow & calibrating it properly.


Level gauges are at best a rough indication.

[steve-ribnet]

Originally Posted by Pikey Dave

inline fuel flow sensors are notoriously inaccurate, especially at low speeds.

They are sufficiently precise (consistent) at high flow rates/speeds for determining efficient boat running setup - for example obtaining optimum engine trim and rev range for fuel economy. They can also highlight problems with the engine or hull that would otherwise go unnoticed.
I had a seam on my tubes that was coming unglued and billowing out at planing speeds but not at rest. I first knew something was not right as the fuel consumption rate was 20% higher for the same cruising speed and load than I was used to.

Depending on the purpose of your boat, I could imagine one burns well under 10% of fuel at low speeds; the rest at high speeds, therefore the accuracy at low speeds is mostly irrelevant.

I wouldn't rely on one for a calculated tank level reading if you are the type of boater to start a trip with anything other than a full tank. If you only ever add the odd few litres here and there, and you are down to the last 1/10th of a tank on the 'gauge', I wouldn't presume there was any fuel left at all!

Having said this, my EP-60r after calibration returns an error of +-1 litre of fuel on 70 litres of use from a 90litre tank through a 100HP outboard. This is an accuracy of +-1.5% and has been within this margin of error over 40 or so trips to the pump. When fuelling the boat on the water I can't judge when the tank is 'full' to within this margin of error anyway. so with proper trip planning and safety margins, the range/duration remaining value calculated using one of these fuel sensors could be useful. I still rely on my Mk1 eyeball fuel level sensor before setting off as I can see inside my tank, and would get level sensor if not, in order to verify tank level.

As with all these gadgets, if you know their limitations, then they can still give useful information, just not perhaps the full picture that you desire.

[Nos4r2]

Originally Posted by steve-ribnet

They are sufficiently precise (consistent) at high flow rates/speeds for determining efficient boat running setup - for example obtaining optimum engine trim and rev range for fuel economy. They can also highlight problems with the engine or hull that would otherwise go unnoticed.

Same kit on mine-EP60R sender via NMEA 2k network and displayed on an HDS7.

I agree-it's good enough to tell me if I'm cruising at the optimum speed. I've got mine set to miles per litre.
I've also got the (US) GPH figures on Smartcraft and they aren't that far removed when I've bothered to work it out.

It only becomes obviously wrong at WOT and displacement speeds.

[Daniel]

Originally Posted by Nos4r2

I've got mine set to miles per litre.

Who you kidding... Litres per mile.

Got the ballistic out of the field yet?

[Nos4r2]

Not yet, though I don't think it's far off. The ground is now 'soft' rather than 'liquid under grass'.

I make about 0.73 miles per litre cruising at 35 knots. I can burn more in my Searider if I get enthusiastic. Worst I've seen at a steady throttle opening was 0.5 mile/litre, though oddly that's not at WOT.

[Daniel]

Interestingly good for the big block opti.

My big block hpdi on a shorter boat (it's a 3.3li tho, yours is 3.0) is constantly over 1li / nm and at WOT the floscan is off the gauge which reads to 90li/hr so in excess of 2li/nm.

[Nos4r2]

I should add that at WOT I don't quite believe the flow meter as the Smartcraft is telling me 22 US GPH/hour which works out at 0.52nm/L, but it says 0.6 mile/litre on the EP60R

[Pikey Dave]

Originally Posted by Nos4r2

I make about 0.73 miles per litre cruising at 35 knots...................... Worst I've seen at a steady throttle opening was 0.5 mile/litre, though oddly that's not at WOT.

That's just what I get, 0.7-0.75nm/l, but at 25kn not 35 That seems to be the sweet spot for the engines, slower actually uses more fuel. I use the fuel info from the engine emm & it's surprisingly accurate.

[Chris]

We were at about 1.2 litres per nm at 30knots on the Etec which seemed reasonable for the big 3.4 litre lump...

[Pikey Dave]

Originally Posted by Chris

We were at about 1.2 litres per nm at 30knots on the Etec which seemed reasonable for the big 3.4 litre lump...

Which sounds about right, I'm doing 1.3l/nm with twin 1700cc v4s=3.4l + extra drag & losses.

[Nos4r2]

Originally Posted by Chris

We were at about 1.2 litres per nm at 30knots on the Etec which seemed reasonable for the big 3.4 litre lump...

Just woke up-what's that in NM/L? Guesstimating says it's about the same as I get.