Tank Balancing

[RD60]

As someone new to twin engines and two fuel tanks what is the suggested practice for tank balancing?
Should the balance valves be left open whilst motoring or are they best closed?

 

[kashurst]

I don't think it really matters. There is an argument that if one tank gets contaminated with water, then you still have a "good" tank. But a lot of boats only have one tank - so again does it really matter? Best thing is to make sure the tank fillers seal properly and there is no water in there to start with.
However to get a good idea of how well your engines are behaving check their fuel consumption over a long run. Close the balance valve before a long journey. Both engines should use about the same amount of fuel. That said - boat fuel tank guages - especially old ones can be a bit "vague". It's well worth upgrading to the new style of linear tank senders as these read pretty accurately and are relatively cheap.