Low RPM cruise

[a64pilot]

Originally Posted by Simi 60

As long as its calibrated accurately

Saying that it would still indicate increased fuel usage, just the actual numbers will be wrong.

Yes, absolutely.
That is a huge, major difference between a quality system and one of the EBay type of things, a quality systems has been calibrated and each fuel flow meter will have its own individual “K” factor that is inputted into the fuel flow computer.
The less expensive ones, well you didn’t pay for that, so your not getting it.

[Dockhead]

Originally Posted by a64pilot

Yes, absolutely.
That is a huge, major difference between a quality system and one of the EBay type of things, a quality systems has been calibrated and each fuel flow meter will have its own individual “K” factor that is inputted into the fuel flow computer.
The less expensive ones, well you didn’t pay for that, so your not getting it.

Indeed. But I think the commercial ones are quite good -- both FlowScan (AFAIK) and Maretron are temperature-corrected and individually calibrated.


But even a bad flow meter will be vastly better than guessing based on miles run on whole tank loads of fuel. There is far too much noise in such a calculation to tell you anything useful.

[Simi 60]

Originally Posted by Dockhead

Indeed. But I think the commercial ones are quite good -- both FlowScan (AFAIK) and Maretron are temperature-corrected and individually calibrated.


But even a bad flow meter will be vastly better than guessing based on miles run on whole tank loads of fuel. There is far too much noise in such a calculation to tell you anything useful.

The reason calibration came up is on another thread I made mention of a mate with a larger beamier and heavier vessel but same engine as ours telling me he gets 15 lph @ 1300 rpm for 8 knots so say his floscan.

Using sight tubes and rubbery numbers I reckon we get 15 lph at 1150 rpm for 7.5 knots and the cummins prop curve chart would support this.

[a64pilot]

Originally Posted by Dockhead

Indeed. But I think the commercial ones are quite good -- both FlowScan (AFAIK) and Maretron are temperature-corrected and individually calibrated.


But even a bad flow meter will be vastly better than guessing based on miles run on whole tank loads of fuel. There is far too much noise in such a calculation to tell you anything useful.

They are.
What astonished me was the Canbus fuel flow from my old boat with a Verado outboard.
If it said I burned 100 gls of fuel, then I could only put 100 gls +or - 1 gl or so into the tank, it was phenomenally accurate, and it did not have a fuel flow transducer, it was calculated fuel burn, not measured.

Very likely I think that the newer Canbus Diesels may have just as accurate fuel flow calculations on the bus, without any kind of external fuel flow measuring device.

[Simi 60]

Originally Posted by a64pilot

Yes, absolutely.
That is a huge, major difference between a quality system and one of the EBay type of things, a quality systems has been calibrated and each fuel flow meter will have its own individual “K” factor that is inputted into the fuel flow computer.
The less expensive ones, well you didn’t pay for that, so your not getting it.

Those eBay cheapies I linked to earlier have a "k" factor, whatever that means

Flow speed range : 0-10LPM
Total flow number: 1-999999 L
White background light LCD
Flow sensor connecting type: OD 13mm
Power input: 12-24Vdc
Accuracy: ±0.5%
k parameter= 6.3

https://www.ebay.com/itm/Liquid-Fuel...MAAOSwJ4hY-hIu

[Kenomac]

I’d spend the money on diesel fuel and continue to use the dipstick.