ok, thanks, what you are saying is water levels CAN be an issue on that route?
I know the Rhine has water level issues , the Porto cruise and the Bordeaux cruises do not (as they empty into the ocean, but Bordeaux can actually suffer tidal issues that cause the itinerary to change).
i am just trying to understand if it's even a need for consideration on this particular river. i spent time on line and it wasn't very definitive