Fuel Guage & Reserve

[Sean farrell]

We have a C24. Sunday we made the trip from Block Island to Cowesett RI which is a distance of 39 miles. We were doing about 25 mph with fuel flow according to the Penta guage of 2.3 to 2.5 mpg. Since we left with 37 gallons we should have arrived with about 17 left. A few miles from the end of the trip the fuel guage started to waiver between 16 to 0 gallons, eventually settling at 0 while underway and at rest.

We fueled up immediately adding 80 gallons and the missing 17 magically reappeared indicating that the tank was not empty after all.

Anyone else get this kind of behavior and if so is it intended as a reserve? If so it is not very helpful.

Thanks
Sean

 

[knotflying]

There is an old saying when flying, " fuel gauges are accurate when they read full or empty" . You should never have left with such little fuel. My rule of thumb is use 1/3 going, 1/3 to come back and have a 1/3 reserve. Although I do not have a Volvo I always use the Garmin for my fuel burn, distance remaining based of current fuel on board and fuel remaining. I have found the Garmin to be very accurate. I also do it the old fashioned way and manually calculate fuel remaining in case I lose electronics.

 

[nzfisher]

I have found the first few things to go south are the mechanical gauges, mechanical latches then the horns on boats. The electronic measurement of fuel use has been very reliable if you remember to "top off" the system when you fill up.

 

[NorthernFocus]

To experienced mariners the reliability of fuel gauges ranks slightly below the weather forecast.

The fairly recent advent of metered fuel usage is, as said in the prior replies, reasonably accurate. It may be off but will at least be consistent so that can be interpreted.