Fuel Tanks

[Lastdraft]

My boat has two fuel tanks supplying two engines independently  but, they are connected to each other with a fuel pipe and an open/shut lever. This lever is in the open position. What would be the reason for this configuration ?  Should I close this lever ? Leave it open ?  Are all twin fuel tanks connected ?

Thanks for any info/advice

[grendel]

its to balance the fuel levels, if you were running on 1 engine you would have one tank full and one half full and wold end up leaning toward the full one

[JanetAnne]

It does allow the tanks to remain constant if, for example, one engine was used to heat water or charge domestic batteries when moored for extended periods.

The tap also allows a tank to be isolated should removal or repair be needed 

[Smoggy]

For rivers only use open is fine, for sea use close the valve (all the time even on rivers) and keep the tanks separate in case of fuel contamination, that way you only lose one engine and keep going.

[BroadAmbition]

However if your tanks are clean and you have confidence that they are and you are running with Soltron (Other brands available) - then I'd keep the valve open to keep them balanced and also enable you to top up both tanks with fresh diesel now and again

Griff

[Smoggy]

Not for sea Griff, you can have full confidence as "it's never done that before" but you only find out about fuel problems when you least need them, you can have tanks full of crud on the rivers and never know it but the first bit of lumpy water and it all grinds to an abrupt halt.

It takes a fair amout of fuel level difference to make any noticable list to most twin diesel boats, mine have been 100 litres different many times with no real effects, I just assume swmbo has been on the cakes again.....

[VetChugger]

59 minutes ago, Smoggy said:

I just assume swmbo has been on the cakes again.....

I'd bet Ali hasn't seen that post!

[BroadAmbition]

Not for sea Griff, you can have full confidence as "it's never done that before" but you only find out about fuel problems when you least need them, you can have tanks full of crud on the rivers and never know it but the first bit of lumpy water and it all grinds to an abrupt halt.

Fully understand and get that one.  However M'lud, some of us have fitted drain tap and a sump to fuel tanks and every couple of years or so drain down any crud, keep the soltron treatment up and have full confidence in the onboard tanks.  Surely there's more than me do this?  That way on the odd occasion we take 'B.A' to sea we never have an issue with tanks getting stirred up

Griff

[Smoggy]

The two seasons before I replaced my tanks I'd done more one engine on low power entrances than I care to remember, I'd cleared most of he bug but had rust coming through too, on the last run out I changed 6 pairs of pre-filters, there's no way I'd have linked tanks.

On my previous boat I'd had both tanks out and cut open to replace rotten steel and got them clean enough to use the house vacuum cleaner inside without violence from swmbo before welding back up, all fuel had been filtered and traeted going back in, I'd only picked up at one marina after that before a sea trip and had fuel issues, found a flake of crud wedged in a pickup pipe that certainly wasn't there before.

We ended up being towed in to kings lynn by skeggy lifeboat as a steering arm snapped on one outdrive, of course it had to be the one still running!!!!!! Could've gone round in circles all day if I'd wanted.

I love seperate tanks.

[annv]

The valve has been fitted for a reason to isolate the two tanks, how many fillers have you often only one filler, your decision i'd personally follow Smoggys reasoning it also provides a comparison between the fuel requirements of each engine. John

[Lastdraft]

13 hours ago, BroadAmbition said:

However if your tanks are clean and you have confidence that they are and you are running with Soltron (Other brands available) - then I'd keep the valve open to keep them balanced and also enable you to top up both tanks with fresh diesel now and again

Griff

I've used Soltron since you recommended it a few years ago, can't help thinking you have shares in this company ?  confident tanks are clean, fuel filters changed and checked regularly. 

Appears to be two schools of thought here, both with merits, the boat came over from France recently with this configuration without issues so for my occasional coast hop and pottering around the broads I think I will leave as is.. Thanks for all opinions, I appreciate.

[Smoggy]

A filter in the balance line would be a good idea, not a setup I have ever seen mind, even better two filters with check valves in parallel facing opposite directions if you have beer tokens spare.