Suggestions for fuel level indicator please

[NUTMEG]

My CW28 ketch has twin fuel tanks (there's posh for you), they sit either side of the engine compartment. They are made from shiny stainless and hold thirty or forty gallons each at a guess. Both tanks were full to the brim when we took the boat over, giving a range of a thousand miles according to the last owner (Volvo Penta MD22). He said I could expect to use about a litre an hour at 15000rpm, does that sound realistic?

Each tank has its own filters, return pipes and taps.

I have only been out a few times and have been using the port tank.

The problem I have is that there are no fuel gauges, nor can I find a notched dipstick as used on both my last two boats.

Any ideas how I can get a measure of fuel level? I think a dipstick would work as the filler pipe run looks fairly straight. But how to calibrate it without emptying a tank and refilling a gallon at a time and 'knotching' a stick.

Any suggestions?

Thanks,
Steve.

 

[sailorman]

approx consumption is 1 ltr per h of hp used.
we have a sight gauge on our 130 ltr tank

 

[prv]

approx consumption is 1 ltr per h of hp used.

That doesn't stack up. We used to have a 20hp engine and a 40litre tank, and I can assure you we had more than 2 hours' range!

Pete

 

[MrB]

He said I could expect to use about a litre an hour at 15000rpm, does that sound realistic?

You need to get that engine technology to the Le Mans 24h guys lol.*

*yes i know it's a typo, 1500rpm not 15000 lol*

 

[sailorman]

That doesn't stack up. We used to have a 20hp engine and a 40litre tank, and I can assure you we had more than 2 hours' range!

Pete

1 litre per hour per 10 horse power used.

 

[SHUG]

Have you thought about installing a sight glass?
You could have a switch-over valve to monitor both tanks. A bit of study of 1/4 inch pipe fittings (or metric equivalent) could lead to a good , reliable,simple system.

 

[sailorman]

Have you thought about installing a sight glass?
You could have a switch-over valve to monitor both tanks. A bit of study of 1/4 inch pipe fittings (or metric equivalent) could lead to a good , reliable,simple system.

with a cock at the bottom too

 

[Rigger Mortice]

Any ideas how I can get a measure of fuel level? I think a dipstick would work as the filler pipe run looks fairly straight. But how to calibrate it without emptying a tank and refilling a gallon at a time and 'knotching' a stick.

Any suggestions?

Thanks,
Steve.

Why not just wait until one tank is empty? Transfer fuel from the other tank to get your calibration. Then transfer it back and calibrate the other tank. I wouldn't bother with doing it a gallon at a time. 5 gallons would be more like it, possibly with single gallons at the bottom of the tank.

 

[NormanS]

I have a similar set-up with a 240 litre tank each side. The tanks have small sumps with drain cocks. I attached thin clear plastic hose to each drain, to make it easy to drain off any dirt or water, which I check frequently, particularly on the day after a rough passage
By starting with one empty tank, and adding 20 litres at a time, while using the plastic tube as a sight glass, I marked off a white board on the side of the tank, every 20 litres. This means that I can use the drain hose as a sight glass, whenever I want to, but technically it is not a sight glass, and I always leave it empty. It was a simple matter to transfer the marks over to the tank on the other side.
I usually run my MD22 at 1800 to 2000 rpm, and use between 2.5 and 3 litres per hour.

 

[blackbeard]

On my boat it's possible to see part of the side of the (plastic translucent) fuel tank. So it's easy to see the fuel level. Easy, did I say? no, almost impossible to be sure.
Incidentally, according to Sea Start I understand, the fuel gauge is a common reason for running out of fuel. Accurate and reliable - not always.

 

[NUTMEG]

Thanks chaps. Of course I meant 15000rpm, no water skiing behind my boat!

I thought 1ltr an hour,was a bit optimistic! My 1GM10 used to do about that.

I think Mr. mortice may be on to the simplest methods but I will check to see if drains have been fitted, rather like the idea of sight tubes. Would remind me to drain water off too. Assuming drains are present!

Cheers all.

 

[bluerm166]

Having had this problem : If a rectangular tank you can measure the cross section and the height required from the bottom to give a nearly full 'round' volume e.g.40 gallons or say 180 litres.Mark 40 gallons by notching a dipstick.Divide the stick into say 5 gallon increments.Probably sufficient.Get e.g.a van dipstick from a breaker or factor and make your own marks.You don't need to know how much is in any tank,simply to have access to measure it.From the maximum capacity choose the next 'round' volume down to start the calibration.

 

[paul-essex]

the Konsort I have just got has a clear stiff plastic tube what you can dip the tank though the deck filler , insert tube put your finger over top of tube lift it up to show level remove finger fuel drains out and store it back in locker

 

[NUTMEG]

Brilliant. Two more really good ideas! Isn't this forum a great resource. Thanks chaps.

 

[LittleSister]

Does it need to be that accurate? All you need is a stick and a bit of rag. Put the stick in, pull out and inspect. Is it wet most of the way up, or only the last inch or so? If the latter switch to the other tank and fill up next time convenient, otherwise forget it for a while and check again sometime. You'll soon get a very rough idea how quick the tanks go down according to hours/distance run. Who cares whether you've used 10.68 litres or 12 litres? Surely all you need to know (especially with tanks that size) is have you got plenty of fuel or not much?

 

[P4Paul]

More cost but you could always go for a remote option.

http://www.tanksrus.co.uk/unitel-hydrostatic-gauge---adjustable-range-900mm-to-3000mm-842-p.asp

 

[single]

Is there such a thing as a gauge for flexible tanks?

 

[Rigger Mortice]

Is there such a thing as a gauge for flexible tanks?

Yes.
Lift the locker lid. Prod the tank with your right hand and say "That's about x% full"
You do need to make sure that your right hand is properly calibrated.

 

[single]

Yes.
Lift the locker lid. Prod the tank with your right hand and say "That's about x% full"
You do need to make sure that your right hand is properly calibrated.

Due to evolution my arm is only just over two foot long and the tank is about five foot away around a corner out of sight

 

[Rigger Mortice]

Due to evolution my arm is only just over two foot long and the tank is about five foot away around a corner out of sight

You need a Darwinian bent stick. (The MkIV version is a great improvement on earlier models)