Fuel gauge accuracy CW 2017- 28

[William Thomas]

This may have been discussed on an earlier post , but here goes---

Up on Lake Powell last week and wanted to run as much diesel out of the tank as possible as trailering in mid June 2,500 miles ,Phx to Lake Huron. Tank read 55% when on plain at 20 Knots and 22% to a 2% red warning light when at 800 RPM,Slow Slow!
Never had this situation as never tried to run fuel down to a minimum level before. What is the believable fuel level? Or is it halfway in between?
Thanks,
Bill T.

 

[BB marine]

viewtopic.php?f=18&t=10780
Unfortunately the factory calibrated fuel gauge is inaccurate. Most Tug and Cut owners do not use the fuel gauge. Most use the Garmin as there fuel monitoring devise which works well if you update the amount of fuel taken on at each fueling. I use this method and find it to be accurate. I felt that the fuel gauge should be more accurate so I spent some time over the winter and came up with a easy accurate way to calibrate the gauge. I posted that on Tugnuts. The accuracy is not good when at a bow high attitude because the sending unit is in the aft part of the tank. It is very accurate when at hull speed. With the combination of the Garmin and an accurate fuel gauge I have a system of checks and balances. The gauge accuracy is within 2 to 5 gallons of my Garmin reading when the boat is level. Before calibrating the gauge it was 15 to 20 gallons

This was taken after a 2 hour run last weekend. When I left the tank reading was 24 gallon and the Garmin was 19 gallons (5 gallon difference ) Returning (2.1 gallon difference) It is not perfect but more reliable. After 2 years of operating the boat I completely drained the tank to see how accurate the Garmin was. After running 234 hours and many fill ups it was off 15 gallons. This prompted my to try to get better accuracy from the fuel gauge. Using both is better then one.

 

[William Thomas]

Thanks Brian,
Will it suffice upon filling the tank to simply "reset" the Volvo fuel screen? I have been doing that. Don't know if that helps the accuracy or not.

What is the procedure to enter the gallons taken on board using the Garmin? Still getting used to all the features on the Garmin. It is truly amazing what info it can provide for us!

Thanks again,
Bill T.

 

[BB marine]

Reset on the Volvo gauge resets the trip data. It will not reset to make the gauge accurate . The Garmin screen A/V, Gauges, Controls > Engines > Menu.
select:
Fill Tank -if you filled the tank
Add Fuel to Boat. - enter the amount of fuel you added
Total Fuel Onboard -enter the total amount of fuel in the tank
These are the options that are given in the menu. If you are filling the tank make sure you have filled it all the way the last 10 gallons can be slow because of the fill/ vent location of the tank. Once filled enter filled tank and the Garmin is linked to the Volvo engine management via N2K. If you are adding fuel say "20 gallons" enter 20gallons, done and the Garmin will add that amount to the existing fuel on board. The only time you would use enter total amount of fuel on board is if you know exactly how much fuel you have on board or if you removed fuel from the tank. Example the Garmin screen reads 50 gallons of fuel ,you remove 10 gallons from the tank. To maintain an accurate reading you must enter 40 gallons total fuel Onboard.
Once you have done it. You will understand it. You must be accurate in your entrees or the reading will be inaccurate. Having both readings Garmin and the Volvo gauges gives you an addition measurement to compare. Redundancy is not always bad!