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Post by chinagirl on Apr 20, 2017 9:52:42 GMT
Hi. We've just bought a SO41DS and have already noticed that the water gauge is not linear. It moves very slowly down to half full and then races down to quarter full and empty much more quickly even though our rate of use is roughly constant. So clearly much more than half the water is registered by the top half of the gauge. That's led me to be concerned about whether the fuel gauge is the same. Running out of water is a minor irritation, running out of fuel is a big problem. So, has any 41DS owner calibrated their fuel gauge against the actual amount of fuel left please? I assume every 41DS will be similar.
thanks for your help
Steve
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Post by rene460 on Apr 20, 2017 11:02:05 GMT
Hi Steve,
Most of our tanks have a roughly triangular cross section at least near the bottom, and possibly some tapering fore and aft. In addition the fuel gauge is generally operated by a float that swings on an arm. Both factors mean they tend to be highly non-linear. I don't think any are equipped with a microprocessor or other equipment to provide accurate calibration.
Our fuel gauge shows full until it is down to about half. Our water gauge is similar. Our tanks are not very high, taller tanks would not be quite so extreme. It is worth having a look at the shape of your tanks, and you will see what I am talking about.
We keep a fuel log where we record the gauge reading (by a sketch as there are not many marks) and how many litres it took to fill. This helps us build up a calibration chart. It also helps to record engine hours when you fill up, at least while the meter is legible, as you can get a good idea of litres per hour if your motoring follows a regular pattern.
Obviously our our tanks and engine size are a very different size to yours, but I recommend keeping a fuel log, starting at the next fill as a starting point.
rene460
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Post by minnewaska on Apr 20, 2017 11:34:27 GMT
Most guages are only correct at full and empty. Don't trust any of them. As Rene says, note the engine hours, when you top up fuel. Your engine docs should have gallons/liters per hour, but round it up. I'm betting about 1.0-1.5 gph, or 4-6 liters per hour. I always top up when I've calculated that I've burned half a tank. Better to avoid condensation in the tank, keeps fresher fuel in the system and alleviates that feeling of "do I have enough fuel". My calc is never off by more than a couple of gallons.
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Post by chuckr on Apr 21, 2017 7:11:41 GMT
Ours does the same - both water and fuel - after 13 years on the boat and 10 years underway we got use to it and make plans accordingly. It is like an old friend that you may not like in the beginning and ever later but you get use it and work with it.
Of course the admiral and I have different opinions on that. When she see 1/4 tank she freaks and thinks we are going to run out of fuel and die at sea while trying to make a port. Me on the other hand remind her this is a sail boat and we can sail into a port if necessary and that sends her downstairs to make sure her will is up to date. And of course when we make it in she tells me how lucky I am to have made it and we when we fuel and fill it is about 80-85% of the gallons - ie we had about 15-20% of the fuel left - makes for a good argument for a while and I told you so on someone's part.
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Post by stan10 on Apr 21, 2017 13:23:53 GMT
Hi Steve.
I have a two year old 41DS and haven't had any problems with either water or fuel gauges. Two water tanks and fuel tank appear to be reasonably accurate and fall with usage as l would expect. Sorry, guess this doesn't help much!
Regards
Stan
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Post by chinagirl on Apr 22, 2017 13:08:05 GMT
Most guages are only correct at full and empty. Don't trust any of them. As Rene says, note the engine hours, when you top up fuel. Your engine docs should have gallons/liters per hour, but round it up. I'm betting about 1.0-1.5 gph, or 4-6 liters per hour. I always top up when I've calculated that I've burned half a tank. Better to avoid condensation in the tank, keeps fresher fuel in the system and alleviates that feeling of "do I have enough fuel". My calc is never off by more than a couple of gallons. Thanks Minnewaska (and the others who replied), that sounds like a plan. Steve. |
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Post by vasko on Apr 30, 2017 9:20:48 GMT
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kev1
New Member
Posts: 4 
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Post by kev1 on Sept 25, 2017 20:53:45 GMT
Hi Steve.
I had just taken delivery of the 41 DS at Chatham when you bought China Girl,we met briefly the day you left.
Over the summer I Worked out how many litres an hour I was using, 3 in our case, then how many hours I could run to use 120 litres. Then I marked the position on the gauge, about half way. and filled to the top of the tank to check. so I now know I am safe to that point. I will do the same to 150 litres next.
Hope you lie your boat
Kevin
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Post by vasko on Sept 26, 2017 3:21:28 GMT
If you want to know how much water exactly is left in the tank - install a flow meter - plenty of garden and house type available for about £20-£30 ...
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