no fuel level sensor

[SteelCruiser]

I have a 10 metre steel long keel cruiser.
There is a large tank in the keel. But no fuel level sensor.
no access for a ‘ stick down the cap’.
I fill it when I can.
there is a pump up to a 10 litre header tank. When motoring, I keep that topped up, idling every 3 hours to refill the header tank.
Having no idea how much fuel left in keel tank is not ideal.
Any suggestions for method( s) to install a fuel gauge?

[jamhass]

Check out "TankTenders". Non-electrical level sensors that require a minimum effort to install and are very accurate. Not cheap. Great folks to work with also.

[rbk]

Keep a log, mark your hours from the meter calculate your fuel usage then you can calculate how much is left in your tank with good accuracy. Should only take a half tank or so to get fairly accurate results. Or the tank tender.

[Cheechako]

I dont remember ever having a sensor, or at least a working sensor on a sailboat. I just logged how much fuel vs how many hours each time I filled up. I did have access to view inside the tank or a dip stick on most boats though. The boat in my avatar burned .65 gal per hour average over the life I owned it... and I only know this from that log.

[SVHarmonie]

If you have access to the top of the tank, and can drill a hole, virtually ANY kind of level sender can be used--even a dip stick (low power draw, and highly reliable!)

[SVHarmonie]

Originally Posted by Cheechako

I dont remember ever having a sensor, or at least a working sensor on a sailboat. I just logged how much fuel vs how many hours each time I filled up. I did have access to view inside the tank or a dip stick on most boats though. The boat in my avatar burned .65 gal per hour average over the life I owned it... and I only know this from that log.

For most sailboats, this works great, and is plenty close enough because they spend almost all their engine operating time at "cruising speed." Everybody should do it, no matter if they have a working fuel gauge or not!

We found it less than usefully accurate for us because we spend a lot of time at "trolling speed" when we are fishing (idle, or just above) or sometimes on a long passage we throttle back 1 or 2 knots from normal cruising speed for fuel economy. It makes a HUGE difference in fuel consumption and total range. Throw in some time motor sailing, and our fuel consumption per hour is all over the map.

Our boat was equipped by the factory with an awesome dipstick. A long piece of polycarbonate, 3/4" wide, and about 5/16" thick. It has a small ( 3/16") hole drilled every 10 liters of tank capacity. It lives full time in the tank and fill tube. Just pull it out, see the highest hole that holds a bubble of fuel, and bob's your uncle. No need to look for an ambiguous wet line. Not even any need to fully remove it from the fill pipe, so no dips.

It was also equipped with a standard electric gauge, which has never worked as long as we have owned the boat, and we have no plans to fix it.

[canman]

Great thread as we are also all over the RPM range so hours run is very ifffy. Our electric gauge at least tells me full , about half full , and near empty on Each of our two 45 gallon tanks. The dipstick idea makes sense. Any links to a kit like the . One that has holes every 10 liters? How does it stay sealed at top of tank?

[Kelkara]

I have a manual pump to transfer fuel to my day tank ... I just count the pump strokes which measures the fuel leaving the tank. I can usually tell the fuel dock how much I'll need to within a couple of litres.



If you can't measure the pump usage, then you can probably install a flow meter on the pump line which will tell you how much fuel you have used.

[okgood]

Every general aviation student pilot is taught to not trust their fuel gauges, and even though they use a dip-stick to check the level of fuel in their tanks, they also keep track of engine hours (before and after each flight) in order to calculate the actual fuel burn for their aircraft. They then use this calculation to better predict fuel needs for future trips. So, perhaps there are best practices you can take from that industry to help you better estimate your fuel burn.

[canman]

We have an amazing water flow meter that is self powered by a simple battery that’s incredibly accurate to the gallon. RV folks use it. Unfortunately flow meters for diesel engines seem problematic because of the return to the tank issue.
Has anyone installed a flow meter to the diesel and a second one on the return? So that you can calculate the exact fuel level s?

[Stu Jackson]

Fuel consumption. Easy. And if you you less, what's the big deal? That simply means you have more left, and less to refill.

[oleman]

We have the old way, a wooden dowel rod of the correct length and the new way, electronic engines have had the ability to calculate the fuel consumption over an indefinite time for at least the past 20 years. Our Cummins ISC engine, put in service in 2001, can indicate liters consumed over many hours. In between those checks there is the float gauge.

[Bill Seal]

If you can get to the top of the tank, drill a 1.5" hole in it and stick in a KUS/WEMA reed switch sender. On our boat, i just epoxied a 1.5" NPT tank flange onto the tank and got the pipe thread version of the sender.

[CarinaPDX]

Another vote for Tank Tender. Mine has been working for 40 years with no maintenance or repair (thinking about it I should lube the seal). It is very accurate and dead simple, using only air pressure. To install drill and tap a #6 hole in the top of the tank and screw in the sensor tube. And as stated earlier, it seems expensive for what it is but the performance is well worth it.

Greg

[Bycrick]

The Tank Tender works fine, but as several people have pointed out, it’s expensive. If you look, every big city will have a distributor for small, pneumatic control systems. I think I went to Parker-Hannefin. A small pneumatic cylinder, two check valves, a small pressure gauge, and some toggle-switch-like valves, a bunch of small hose barbs and fittings and some lengths of different-colored 1/8” hose later, I had a six-tank versión running for just slightly over $200. That was 1998 and it’s still working.