Thanks, I remember a mate telling me they always swim up current. He has seen them during the incoming tide turn around and swim back towards the sea against the current.
But that would suggest, that in many cases the outgoing tide might be better then the incoming because there is more outflowing water.
Just been looking at same satellite images which are harder to find then the normal Google earth and it shows the river at low tide, but more importantly it shows the shallows which are normally hidden. From that I can tell the main path of the main current.