Is it a big deal to replace the sending sensor, or the full sensor and display units?
Something’s not causing an accurate reading.
David Watson
Does the gauge display full when full and empty when empty? The tank is a smaller dimension when empty than when full. As a result when the gauge reads 1/2 you will have much less than 1/2 a tank of fuel.
If the gauge does not display correctly, the simplest course might be to get a new sending unit and panel gauge.
I like the sending unit type that has a magnet sliding/floating on a vertical rod.
To test the panel gauge, take the wire off of the sending unit. The gauge should go to one end of its range. Now ground the sending unit wire. The gauge should go to the other end of it’s range.
Ward Woodruff
N33 #8 Margery
Niantic Bay, CT
Not knowing what you have or where it is makes it hard to answer, David.
Joe Valinoti
S/V iL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA
Sorry, Joe. I’m in the process of buying a 1988 N30 Ultra in RI.
David Watson
It is easy to check or replace either the sender or the gauge and as someone else posted, simple to troubleshoot on a 30U.
Joe Valinoti
S/V iL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA
I think these gauges are less than ideal The tank is not square and the gauge assumes it is. A receipt for running out gas… We simply track engine hours and use .4 gal/ hr for my W21. Calculation is spot on.
Removed the sender and gauge / wiring. Made a small aluminum plate from some scrap and used the same mounting holes as the sender. Used silicone as a gasket as it expands in the presence of petroleum
I do the same as Thor on our 26C with Beta 20, but use 1.6 litres/hour, as it seems to track well. Generally on fill, I’m less than 10% off my guess (e.g. last fill was “should take about 40 litres, maybe a bit more” and it was 44 litres filled).
I CNC cut a plug out of 1/8 aluminium and used a commercial goopy gasket material designed for diesel, or so it said. I’m sure Thor is 100% correct on his idea to use silicone, (he’s a smart man) but I had this stuff on hand for an unrelated project, so I just used what I had.
Don’t know if Thor quoted Imperial or US gallons, but if US gallons, that’s 1.51 litres/hour, close to our 1.6 figure. I generally fill up when convenient, around the half-full or maybe one third full by calculation comes up.
JohnS NS26C 046 still in the water at Bath, ON.
I’m looking into replacing both the tank sender and gauge on my 30U. The current sender is a lever type (see photo), and I have to tap the gauge to get accurate reading. At the moment I plan to use a rod type with a donut like float in the tank. I think it will be better than the lever type due to irregular shaped tank.
As i understand it, the hole for the tank senders is a universal size as are the mounting screws. For the rod type sender, you need to measure the internal tank depth where the hole is located to buy the correct length. Also note that the screw holes and gasket are not equidistant, you must orientate the sender correctly when installing them.
I believe you can also get a NEMA 2000 adapter to attach to a regular sender, to them connect to NEMA 2000 network. My Garmin chartplotter can read and display fuel level. And I think it can be calibrated to accommodate for the irregular shaped tank. I need to look into this further.
Also, following another INA member’s suggestion, I installed a T-fitting on tank at fuel return hose location. Through the T-fitting, I can dip the tank with a stick. After draining the tank I added 5 litres at a time and wrote down the measurement on the the dip stick.
Drain the fuel into jerry cans, then add back a few gallons/litres at a time to calibrate it. I did this in the summer, used a small $15 pump connected to a cordless drill.
Cheers
Don
My boat must be the anomaly as I find my gauge to be pretty accurate. I never go below 1/4 of a tank. The main thing is that I remove the sender each spring, insert a tube and pump the very bottom of the contents into a clear jar and see what’s in there.
Joe Valinoti
S/V iL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA
Don;
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you are right, most are “standard” mounting, and, those that aren’t you can get adapters for.
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The fuel tank on the 26 at least, has most of the fuel at the top half, then tapers down.
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The old '50s style of fuel gauge /sender combo is not accurate. Nobody remember having cars that had “irregular” fuel gauges? I do! Now in the last decade or two, with computerised cars, fuel sender outputs are interpolated to give an accurate reading. You can “balance” the old style with resistor networks, but it’s been years, and the accuracy is better, but…
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I have made NMEA2000 interfaces (2 for Raymarine Seatalk version 1) using Arduino Due computers and CANbus interfaces. Worked absolutely fine, but the old Raymarine V1 stuff is now out of the boat and we are NMEA2000 through and through.
I do have ultrasonic sensors here beside me (DS1603L) that I’m going to program to give “fine/so-so/do-something” readings on my chart plotter for fuel and holding tank. Will see how it goes.
I have attached a DXF file (hope it goes through) for the fuel sender mounting/blanking plug I made; the flange is wider (no problem on our tanks, at least the 26C) for a wider gasket area, and centre popped the centre so I can easily drill and tap a hole if required.
JohnS NS26C 046 Last Nonsuch still in the water at Bath, ON.
(attachments)
FuelSenderBlankingPlugV3.dxf (106 KB)
Years ago, when the fuel level was low, I installed two aircraft-grade inspection plates (fore and aft) in my fuel tank. After that it was easy to pump out the remaining diesel and totally clean the tank. Once done I filled the tank in increments of 5 gallons and, using a marking pen, marked off each increment on the wood trim around the fuel guage. This made it super-easy to read the fuel level.
Phil Harmeson
Catharsis.
NSU30 #285
Traverse City, Michigan
Great thinking !!!!
Cedric Single Malt
26C #207
Chester Nova Scotia
I don’t like to trust fuel gauges in irregular tanks. In a 30U there is great access to the tank so I replaced the elbow for my vent with a tee and a pipe plug on top. I keep the appropriate wrench and a few “dip sticks” on the shelf nearby. As I almost always fill my tanks from a jerry can I marked the tank in 20 litre increments. I now periodically (based on hours) pop the plug out, dip the tank, and read off how many jerry cans I can safely add.
Paul M
NS30U #211, Sandpiper
Cowichan Bay, B.C.
My tank area looks nothing like yours even though our boat numbers are close. I’ve never run out of fuel and if I did, I keep a 1 gallon container as a backup.
Joe Valinoti
S/V iL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA
Generic fuel gauges are linear so they really measure the height of the fuel in the tank, not the quantity.. I have the same tank set up as Paul M and know that my fuel gauge will drop a lot faster going from 1/2 to empty than full to 1/2.
Bill M.
Summer Song
NS 30U #335
Noank, CT
Thor, you did not say wether you are using Imperial or U.S. gallons.
Mark Powers
Good question. And the answer is not simple.
Westerbeke states:
Typical Fuel Consumption Rate . . . .063 US gal/ HP/ hr
Typical Fuel Consumption Rate at 2500 RPM
When wheeled to Turn 3000 RPM .8 US gal/ h r
So that is .063 x 21… or 1.3 gallons per hour @ 2500 rpm… hmmm
@ 3000 they state .8 US Gal/ Hr
We have over the years found at 2500 rpm, 0. 4 Imperial Gallons per hour works, or 18 l / hr In US Gallons that is ,48 USG/fr
For example the last time we calculated 10 and used just under 8, but there was a good deal of anchoring in the 10 calculation. But just running at 5.1K @ 2500 rpm… will be .4 IG/hr every time
We rarely upload more than 10 Imp Gallons…
The tank is 24 USG or… 20 IG or 91 l..
Hope this clarifies the numbers.