Fuel Gauge, slight tube or leave it be

N4712 said:

They're are way more accurate solutions out such as Maretrons. No need for those big pulse dampeners either.

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Although my 32' Halvorsen has a FloScan, it's not the easiest thing to calibrate...no matter what anyone says. In my (new to me) boat, the addition of the multi tank "Tank Tender" is most welcome! Other than a sight tube, the "Tank Tender" is the most accurate devise out there. (Dip sticks not withstanding.) MY OA 42 has both.

Question on the Flosan.....Since there is a return line, is there a way of calibrating these to somewhat accurately measure Accurate fuel usage since some is being returned to the tank?? Or is installation in the final feed line accurate?

I have mechanical float gauges on both tanks...One easy to read through a glass port in the settee foor, the other I have to pull some panels to see. Not a big deal, and they appear pretty accurate, but i am curious on the Floscan.

Heron said:

Question on the Flosan.....Since there is a return line, is there a way of calibrating these to somewhat accurately measure Accurate fuel usage since some is being returned to the tank??

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This is done automatically in the FloScan's algorithm. The hardest thing to accomplish is an accurate calibration of the "fuel used." Instructions came with the unit for the calibration procedure but do to my limited ability to comprehend instructions, I never achieved the 1% accuracy that FF speaks of. Although it sounds neat, I would never buy another one.

Codger2 said:

Although my 32' Halvorsen has a FloScan, it's not the easiest thing to calibrate...no matter what anyone says. In my (new to me) boat, the addition of the multi tank "Tank Tender" is most welcome! Other than a sight tube, the "Tank Tender" is the most accurate devise out there. (Dip sticks not withstanding.) MY OA 42 has both.

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Yes that's what's nice about the maretron's. They make them super simple to calibrate. Google Maretron FFM-100 Manual to get and idea

Heron said:

Question on the Flosan.....Since there is a return line, is there a way of calibrating these to somewhat accurately measure Accurate fuel usage since some is being returned to the tank?? Or is installation in the final feed line accurate?



I have mechanical float gauges on both tanks...One easy to read through a glass port in the settee foor, the other I have to pull some panels to see. Not a big deal, and they appear pretty accurate, but i am curious on the Floscan.

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Yep, the Maretrons measure both sides. Cool thing is you can set the display up to display any combination of numbers you want like return amount NMPG, etc. The Maretron flow sensors even have temp sensors in them.

N4712 said:

Yep, the Maretrons measure both sides.

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Ah...I see. They have a flowmeter on the return leg as well...

Codger2 said:

This is done automatically in the FloScan's algorithm. The hardest thing to accomplish is an accurate calibration of the "fuel used." Instructions came with the unit for the calibration procedure but do to my limited ability to comprehend instructions, I never achieved the 1% accuracy that FF speaks of. Although it sounds neat, I would never buy another one.

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I didn't even attempt to calibrate the FloScan. Actual fuel consumption is about 70% of that displayed, so I just use mental arithmetic.






FloScan factors both fuel to engine and well as the return to tank, so there are two measuring devices for the engine.

sight tubes

We bought a trawler about 9 months ago. Though she is work in progress she is functional and we have taken numerous short day and weekend trips locally learning our new boat. Her twin tanks approx. 400 gallons were filled upon us receiving the boat. I have been watching the sight glasses pretty regularly and became concerned when they didn't show the fuel usage I figure we were using knowing how many hours I had run the engine. I had checked the valves at the top and bottom more than once to ensure they were open. This weekend while in the engine room checking things over I reached over and thumped the fuel tanks. To my horror they sounded really empty still showing about 3/4 full in the sight tubes in both tanks. I shut the valves drained the sight tubes and reconnected them. turned the valves on and low and behold they show about 1/8 full each tank. I am confused how can sight gauges be that far off. Do I have a venting issue. Ideas anyone? Considering a alternate fuel monitoring system that doesn't require going to the engine room to look. But I figured the sight glasses were probably the most accurate way to go and it never hurts to take a peek in the bilge.

Sight glasses are accurate. They require that both the top valve and bottom valve be open at the same time to get a reading. At times valves are installed incorrectly and it may appear to be in the open position when in fact it's closed. So, "open" the bottom valve and then open and close the top valve to see if you get a reading in one of the positions. If not, change the position of the bottom valve and repeat the top valve routine. You should get a reading. If not, you probably have a clog in one of the valves. The sight glasses do not depend on a vent to operate. Good luck.

jetmech59 said:

I figured the sight glasses were probably the most accurate way to go and it never hurts to take a peek in the bilge.

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They are. So as Hmason suggests, you have some sort of problem with the valves on the sight tubes or you are positioning them incorrectly.

They should be closed at all times unless you are actually taking a reading. This is to prevent a fuel spill into the bilge of your boat if a tube cracks, splits, or breaks and having that fuel pumped overboard by the bilge pump(s) and netting you a big fine if the spill is traced back to you.

When you want to know how much fuel is in a tank, open the valves at each end of the tube. get your reading, and then close the valves again. The fuel level in the sight tubes will not change again until you open the valves again for another reading.

When you have the chance, affix a yardstick to the side of the tank alongside the sight tube. Divide the gallon capacity of the tank by the number of inches high the tank is and you will know how many gallons each inch represents. Cheapest tank level indicator you will ever find and it's pretty darn accurate.

Upon your recommendation I found that I was turning the upper valves to the off position when trying to get a reading. They are a lever type ball valve and when the handle was lined up with the line I assumed it was open not the case . Other than feeling like a dummy I feel much more confident about my fuel monitoring system now. thanks

Sight tubes all the way. My fuel gauges don't work right now. All three are wrong. In my experience the senders seem to fail frequently. The floscan is great - but mine doesn't read the fuel used by my generators. I used them a lot in Alaska. As mentioned before, sight tubes don't lie.

Richard

The floscan is great - but mine doesn't read the fuel used by my generators.

Either get a hour meter for the noisemakers and do an estimate, baased on run time ,

Or get a cheap copy of a Flow Scan to keep track.

hmason said:

When you have the chance, affix a yardstick to the side of the tank alongside the sight tube. Divide the gallon capacity of the tank by the number of inches high the tank is and you will know how many gallons each inch represents. Cheapest tank level indicator you will ever find and it's pretty darn accurate.

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Careful, that only works if the tank is even shaped and not tapered to match the slope of the hull or some other odd shape.

Have an 8 position Tank Tender system to measure the 2 fuel and 5 water tanks. The John Deere display has a real time GPH function utilizing data from the engine computer. Dealer swears they are very accurate and don't require calibration. We shall see. Extremely happy with my Tank Tender system.

Ted

When I installed my new plastic tanks, I left a slot in the supports on each tank so I can see the level directly. On initial fill I stopped every five gallons and marked the tanks. Now with a quick look I know exactly how much fuel I have. I also monitor engine hours. That said, since my four year average fuel burn is 0.35 gph, I don't worry too much about fuel.

FF said:

The floscan is great - but mine doesn't read the fuel used by my generators.

Either get a hour meter for the noisemakers and do an estimate, baased on run time ,

Or get a cheap copy of a Flow Scan to keep track.

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The generators do have hour meters. I don't know their burn rate yet though.

Codger2 said:

Over the years and 9 different boats, I've had just about all of the tank measuring devises there are. FloScans, Tank Watch, Solo, etc. The best (fool proof) gauge I've ever had (and have today ) is the Tank Tender. No electric or floats...just some 1/4 in plastic tubing & barometric pressure. (The barometric pressure is free!)

The Tank Tender - by Hart Systems, Inc.

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A second vote for tank tender. I find it to be just about as accurate as dipping.

Sight tubes on both saddle tanks with crossover that I always leave open. An old salt told me long ago to use the sight tubes for fuel gauge only. This makes you go down into the engine room every day and while down there check all fluids, bilge condition and other system checks. Our engine rooms should not be a place we try to avoid!Simple and preventive all at the same time.

Capt.Bill11 said:

Careful, that only works if the tank is even shaped and not tapered to match the slope of the hull or some other odd shape.

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Good point. The bottoms of our tanks are slightly angled down and the gravity feeds are at the lowest point. The previous owner who had the tanks fabricated and installed calibrated them by adding ten gallons at a time and putting the number on the sides of the tanks next to fuel levels in the sight tubes.