External Fuel Level Indicator

[cobbcfi]

Although I have searched and come up sort of empty, like my fuel tank does when my gauge says I still have some, I am looking for a fuel level gauge that I can install to the side of my fuel tank that with a little effort and moving a floor panel I can look down at a glass tube and it will show me exactly how much fuel is in fact still in the tank. I have replaced the sending unit (several times) wires and the gauge on the console but after so many fails/SeaTow (and SeaTow is getting annoyed) I can't bring myself to trust it anymore. I am not cheap, but when I put in 20 gallons and I think I burned 15 the gauge says I have 1/4 a tank, then I put in 30 gallons for the next trip I think I burned all of it, the gauge says there is still some in there when in fact I burned all of it plus what was left over from the last trip. I want something that I can look at mounted to the side of my fuel tank that is allowing fuel from the tank to fill the device so I can look down there and say "yes, I have exactly that much fuel on-board". I know the hazards of cutting and drilling into a previously filled fuel tank (I work for Boeing) but I want a fail proof scale of some sort that I can fabricate to my fuel tank that will give me an honest answer of whats really in there.. After some trial and error I could eventually mark the device to indicate in gallons what is remaining which would help tremendously.. I hold 100 gallons of fuel and prefer not to carry that much weight in fuel for a 2 hour cruise so I like to keep the fuel down for weight and cost savings (yes I am a pilot too)..

Any help would be greatly appreciated

 

[roscoe]

Re: External Fuel Level Indicator

Sorry, can't help with the sight glass for your fuel tank.
But, there is no reason why the gauge can't be calibrated to accurately reflect the correct fuel level.
Either by re-marking the gauge to show the true "empty" mark, or by using a different sending unit.
Everything can be fixed if you throw enough money and expertise at it.

 

[Bob_VT]

Re: External Fuel Level Indicator

Interesting thought. A site glass would require allot of work to add on and it would be nothing more then a clear tube that would have to be installed into (Onto) a tank and absolutely leakproof. Nice idea but it would require too much to install.

I would go with a new sending unit and depending on the boat....... possibly a gauge to monitor fuel usage.

Nice avatar picture!

 

[Home Cookin']

Re: External Fuel Level Indicator

I suggest you take the approach more like a boater than a pilot.

First, boat fuel guages are never accurate. Never. Each one is personal to the boat and you have to learn its language. I ahve one that stays on F until there is 1/4 and then it drops to say "half." When there is 1/4 showing, it's about 2 gallons. So I treat it like the warning light on a car's guage.

Second, you can't estimate fuel consumption in a boat b/c of the varying speeds plus wind/current that affects it. You carry enough to use 1/3 out, 1/3 back and 1/3 reserve. You have left out the the last third. So in an effort to save weight you added wait--as in waiting for sea tow.

Third, running a tank to the bottom is the way all the nasty stuff gets stirred up and sucked up into you motor. Tanks in a marine environment are nasty.

Fourth, due to ethanol plus humidity (Charleston humid?) you should keep the tank full to minimize the amount of damp air that gets sucked in the tank, both from displacing fuel and from the tank's breathing with temp changes.

Fifth, you need to carry a couple gallons in a jerry can as your reserve--which cancels out your weight objective, and takes up space, but will make your day a lot smoother. Or fill the tank.

Finally, all that work so you can stick your head in a hole and know that you are out of gas seems more trouble than it's worth just to know; it doesn't solve the problem. May be easier to add a reserve tank. Or fill the tank.

 

[Scott Danforth]

Re: External Fuel Level Indicator

Im going to agree with Home Cookin's comments and add a few

here is the long and short skinny on fuel tank senders and gauges. the air-core motor in the gauge costs less than $1 to make. the whole gauge costs less than $3, and the OEM buys them for about $7. Fuel senders are about twice as expensive as the gauge. the sender is designed under the principle that the fuel tank is square, and constantly level. unfortuneately they are not. The tank is probably v-shapped, and the boat will never sit level, ever. This is why boat tanks with senders in the back read full until they are nearly empty. This is also why a sight tube wont work, however a completely opaque or clear tank would. you would need to have a minimum of 3 sight gauges, on at the front of the tank, one mid tank, and one at the back of the tank.

There are extremely accurate gauges that you can get. they measure the fuel level ultrasonically. the sender cost alone is about $400, the required software, hardware, etc. to display to the gauge is about another $600. I put these on generator skids intended for desert deployment on critical installations because the fuel level was a critical operation.

If you want accurate readings, get a fuel flow meter with a total flow analyzer. many higher end GPS's have them as an option (Garmin for instance). that way you know how much fuel your burning, and it can total your trip burn. this will do a few things for you. it will optomize your operation of the boat if your intent is to cruise at maximum efficiency, and it will tell you when you get close to empty needing to make arrangements for sea tow or tow boat us or to head to the nearest fuel dock.

However from your post, your only putting in 20 gallons here and 30 there. I would fill the tank and go boating. Been in too many boats that have run out of fuel because of a wind change and the operator "thought I would have enough fuel" always follow the 1/3 rule.

 

[Bondo]

Re: External Fuel Level Indicator

Ayuh,.... And,.... a sight glass would require a hole in the bottom of the tank,...

That would violate both the Coast Guard rules of fuel containment, 'n Common Sense,...

I suggest you learn to run on the 1st 1/2 of the tank, insteada the last 1/2 a tank,...

 

[Teamster]

Re: External Fuel Level Indicator

I would get a Lowrance sonar/gps and use the Lowrance ep-60 fuel floe meter,..........

 

[Bayou Dave]

Re: External Fuel Level Indicator

You need something like this: Oil tanks in a home usually have these type of gauges.

Amazon.com: R W Beckett Corp 4504 KING Oil Tank Gauge: Home Improvement

 

[pckeen]

Re: External Fuel Level Indicator

If you are running out of gas regularly, you may be doing one of two things: running repeated trips without refilling, or taking too long of a trip for that boat. Always keep it full.

 

[Thalasso]

Re: External Fuel Level Indicator

Glass gas gauge below decks? That would be illegal by CG standards


Let me google that for you



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[Bayou Dave]

Re: External Fuel Level Indicator

Glass gas gauge below decks? That would be illegal by CG standards


Let me google that for you

The one I mentioned is plastic. (Large, easy-to-read, plastic vile includes UV inhibitors, and is the most break-resistant on the market)
There are lots of them out there to choose from.

 

[Bondo]

Re: External Fuel Level Indicator

Glass gas gauge below decks? That would be illegal by CG standards


Let me google that for you

The one I mentioned is plastic. (Large, easy-to-read, plastic vile includes UV inhibitors, and is the most break-resistant on the market)
There are lots of them out there to choose from.

Ayuh,.... Never seen a boat gas tank with a spare 2" pipe couplin' in it,....

Don't think yer gauges are Coast Guard Approved either,...

Another Coast Guard regulation is the fuel tank can only have openin's on the Top of the tank,...
No bottom drains,...
No sight tube fittin's,...

 

[Bayou Dave]

Re: External Fuel Level Indicator

Ayuh,.... Never seen a boat gas tank with a spare 2" pipe couplin' in it,....

Don't think yer gauges are Coast Guard Approved either,...

Another Coast Guard regulation is the fuel tank can only have openin's on the Top of the tank,...
No bottom drains,...
No sight tube fittin's,...[/QUOTE

That kills this method.

 

[Home Cookin']

Re: External Fuel Level Indicator

so it sounds like the OP's solution fits with the old "if it ain't broke, fix it until it is."

And even I have to remind myself that the E on the guage does not stand for "Enough."

 

[UncleWillie]

Re: External Fuel Level Indicator

The problem with tank mounted sender in a boat is that the boat is never level.



I installed a Fuel Flow Manager.
You tell it how much you pumped into the tank, it tells you how much is remaining.
It is consistently accurate to 0.1 gallons after calibrating to your boating style.

 

[Idlespeedonly]

Re: External Fuel Level Indicator

Throw a 5 gallon gas can in it somewhere.

 

[Pez Vela]

Re: External Fuel Level Indicator

I haven't seen such BS answers in a long time. The best sight gauge I have ever seen was on Nordhavn yacht I poked around on at a boat show. Check out this blog where they discuss it a little bit.MV Dirona Blog - Tuesday, 16 March 2010

 

[Bondo]

Re: External Fuel Level Indicator

I haven't seen such BS answers in a long time. The best sight gauge I have ever seen was on Nordhavn yacht I poked around on at a boat show. Check out this blog where they discuss it a little bit.MV Dirona Blog - Tuesday, 16 March 2010

Ayuh,.... Really,.... Diesel fuel, 'n gasoline are Not the same,.....

 

[Pez Vela]

Re: External Fuel Level Indicator

Please continue that thought and I am sure I will learn something about sight gauges and their proper application. I'm always anxious to expand my knowledge base.

 

[JimS123]

Re: External Fuel Level Indicator

At the Antique Boat Museum in Clayton, NY there is a mahogany marvel that is dubbed the "largest runabout in the world". She's equipped with a 12 cyl Packard engine that was originally a PT Boat engine. The boat regularly provides river cruises for as I recall $300 an hour. It takes avgas to run her.

After each cruise they fillerback up. The fuel gauge is a 5' long oak pole they stick in the top of the tank. Its graduated in 1/4 tanks.

More than one way to skin a cat.....LOL. Google "Pardon Me boat".