Auto refuel for IJN submarines on US submarines

[Superben]

My ubmarines were near low fuel and I give the order " return to Rabaul " and the turn after ( they were in the middle of no where ) they were full of fuel .... What a miracle ...

But the funniest is that in the same turn american submarine in the area lose all their fuel .......... So I think that japanese are pretty good thief for fuel

[zed]

What happens is this:
your subs hit red, then some ship of yours passes through the hex, the subs refuel at sea. I have seen it happen. When it first happened I wondered the same thing as you do.