Balancing fuel tanks

[Mike2425]

Hello All, just taken ownership of a 2005 Antares 980 with twin 200hp Nannies. Still trying to familiarise myself all things peculiar to this boat. One thing I can't get my head around is that the previous owner said that there was no way of balancing the twin fuel tanks, one tank for each engine !!! I've had a look around and can not see any piping from one tank to the other, surely this can't be right ?
If this is correct, has anyone fitted a balancing pipe ?

Thanks.

 

[Plum]

Hello All, just taken ownership of a 2005 Antares 980 with twin 200hp Nannies. Still trying to familiarise myself all things peculiar to this boat. One thing I can't get my head around is that the previous owner said that there was no way of balancing the twin fuel tanks, one tank for each engine !!! I've had a look around and can not see any piping from one tank to the other, surely this can't be right ?
If this is correct, has anyone fitted a balancing pipe ?

Thanks.

If that was mine I would not fit a balancing pipe and retain your totally independent two propulsion systems avoiding any risk of contamination/bug from one tank affecting the other. Any fitting, pipe, hose,valves fitted at the bottom of the tanks creates more opportunities for leaks.

 

[Mike2425]

Thanks for the reply, it just seems odd that one tank, in my case because of diesel heater, empties faster than the other. On my last boat, twin engine twin tank, it had a levelling pipe ! Hey Ho, each boat is different .

 

[Alicatt]

The two engine feed tanks on my boat can feed each engine independently or feed both engines from either tank plus there is a balance pipe between the tanks.
However the excess fuel sent to the injectors is fed to a separate 45 litre tank for the Webasto, when that tank is full the excess from that is fed back to the main tank amidship, when all valves are in the open position as per the user manual, but you can shut the feed off to one or both engines from each tank independently.
The auxiliary tank under the starboard bunk in the aft cabin is slightly lower than the main tank by about an inch or so, boat is in all imperial measurements as are the nuts bolts etc. except for the new equipment fitted like the Racor fuel filters. Great having to keep a set of imperial and metric spanners etc.

 

[Momac]

If the tanks get out of balance just add more fuel to the tank that is low.

 

[Greg2]

Thanks for the reply, it just seems odd that one tank, in my case because of diesel heater, empties faster than the other. On my last boat, twin engine twin tank, it had a levelling pipe ! Hey Ho, each boat is different .

Not odd really - many boats don’t have a balancing pipe as in reality for most leisure mobo use it isn't necessary. We had one on a Broom Ocean 37 but never used it and our Hardy doesn’t have one and whilst the port tank does get a little lower due to heater use during the winter , in the context of the capacity of the tanks it isn’t an issue.

As already said, it can also be beneficial to keep the two two fuel supplies separate.
.

 

[Sticky Fingers]

Not odd really - many boats don’t have a balancing pipe as in reality for most leisure mobo use it isn't necessary. We had one on a Broom Ocean 37 but never used it and our Hardy doesn’t have one and whilst the port tank does get a little lower due to heater use during the winter , in the context of the capacity of the tanks it isn’t an issue.

As already said, it can also be beneficial to keep the two two fuel supplies separate.
.

Yep agree with this. Having two separate tanks and switchable supply options got us out of trouble on a delivery (at least for a day or so) with a fuel bug problem in one tank. My own boat has two separate tanks, IIRC the stbd tank runs the heater and the port the generator, so that balances out the usage a bit although I don’t use the genny much.

 

[DavidJ]

Having all the valves with a balanced system saved my bacon last year when my boat buyer turned up for a trial and one of the engines just stoped due to fuel blockage (I think the truck journey from Spain must have shaken up the crud in the tanks)
The broker switched over to the “good” tank, engines started and a successful trial.
I then picked up a bill for tank cleaning but to be honest I was glad the new owner didn’t have to experience this a week into new ownership.

 

[Bandit]

I have twin tanks and a transfer pump on my boat for 17 years now, I have never transferred fuel or see the need to.

The big advantage is if you get fuel contamination or water in one tank you don't unknowingly contaminate the other tank.

The normal thing is your port engine draws and returns diesel to the port tank only, the Starboard engine only the starboard tank.

It is a boat so don't top up but fill up, the only time you have too much fuel on a motor boat is when it is on fire. Record how much fuel goes into each tank and follow it as it is a good indicator of an engine or drive problem.

 

[Montemar]

Fit a balancing pipe with a tap in it so it can be switched off unless needed.

 

[Alicatt]

Fit a balancing pipe with a tap in it so it can be switched off unless needed.

Have one at each end of the balance pipe on the Ocean 37

 

[Momac]

My boat has various valves that are normally set so each engine draws and returns fuel from its own tank . As said this is in the hope that a fuel issue is confined to one tank , which is in itself not a certainty if the source of the fuel issue came from the fuel supplier.

I have never found the need to alter the valves but they can be set so both engines use one tank. I don't think the balancing would occur under gravity since this is not an option in the instructions , although I have never tried it.




I compensate when refuelling for the often lower fuel level in the port tank caused by the use of the heater. The amount to add extra to the port tank is substantially via observation of the fuel level gauges and guesswork.

The weights of the contents of the holding tank and the beer/wine lockers also have potential to cause adverse weight distribution. But I don't really worry about that either.

 

[Greg2]

The set up that Momac has strikes me as being sensible as it keeps the tanks separate but enables both engines to run of one tank in the event that the other tank is contaminated. We can’t do that but then we can run on one engine and still go in a straight line due to being semi-displacement with a keel.

 

[Momac]

The set up that Momac has strikes me as being sensible as it keeps the tanks separate but enables both engines to run of one tank in the event that the other tank is contaminated. We can’t do that but then we can run on one engine and still go in a straight line due to being semi-displacement with a keel.

I had to shut down one engine last year for about half an hour due to an overheat alarm . Only doing 5 kts (a bit less on one engine) . To my surprise the boat didn't try to go around in circles and steered quire well . It a planing hull on out drives.