Forums, Engine, Gearbox, Stern Gear, etc, Fuel tank gauge

marisco at 08/06/2016 21:24:06
My fuel tank gauge is a length of discoloured hose pipe – no longer up the job.

Wondering what gauge system other boats tend to have ? Someone suggested I could just stick a ‘dipstick’ down the fuel cap – but I don’t know if there are bends in the pipe ?

And what capacity tank am I likely to have – original from 1977 I think, looks stainless steel ?

And what is typical fuel consumption (I’ve got a 20HP BUKH) ?

Sorry – too many questions !

Thankyou, Paul

George Isted at 10/06/2016 20:36:08
Hi Paul,
if the sighting gauge (posh name for the pipe) is discoloured it’s easy enough to replace, there should be a separate stop-cock for the pipe so it can be isolated and removed – just make sure you switch it back on or you will get a false reading (guess how I know!).

The tank is about 45L or 10 gallons if it’s the original from 77 – which I expect it is.

Consumption is hard to say because it depends on how much welly you give the engine. My 2GM20 Yanmar uses about 1L/hr at 1800-2000 rpm but this rises to 1.5L/hr at around 2600 rpm (or 5.5kts boat speed with a clean hull). This should give you an indication

Concerto’s engine/prop combination seems happiest at around 2200 rpm but all engines will be slightly different.

Other owners with the same BUKH may be able to offer a better guide.

marisco at 11/06/2016 13:34:41
Many thanks !

Alastair D Pugh at 11/06/2016 14:42:19
A word of caution – my sight tube was yellowed and hard to gauge so I replaced it during the winter with a clear braided poly one. It is now even more difficult to gauge the level even with a torch shone on the bulkhead behind. What is needed is a float and maybe I’ll get round to that next winter.

While you are there, look for the tank overflow/breather – i.e. where does the fuel go if you fill the tank too full?

George Isted at 14/06/2016 16:38:11
I use a small torch to help seeing the furl level as suggested by Alastair. With the torch shining aft from ahead of the pipe (hope that makes sense) it’s generally possible to see the level. I now only use white (road) diesel in the tank which makes it a bit harder to spot than red diesel.
Edited: George Isted on 2016-06-14 16:38:39

waratah912 at 16/06/2016 20:27:53
If you empty the tank, it’s worth taking the time to refill it using a 5l container and marking the level for each 5l on the tube. 5l is approx three / four hours motoring, makes the maths easy.

Alan Dixon at 28/09/2016 16:29:23
Measure the tank in metric.
one litre = one cubic CM
you can then calculate the volume of the tank and the graduations against the sight glass

waratah912 at 28/09/2016 16:46:28
er – that would result in a rather large over estimation of the tank capacity
http://www.metric-conversions.org/volume/liters-to-cubic-centimeters.htm

Alan Dixon at 28/09/2016 17:04:14
Sorry decimal point in wrong place 1ltr of course = 1000 cm3