[Imp]

Just a simple thought here but you say its a river crossing & no way to cross. Are you using the map generated or using a ready made one. If the later which one because there is a chance that despite the fact it looks like a river crossing map it might not have been built correctly.
In that case no barges or rubber boats as the game does not know its a river so all you have to do is give the map number for it to be fixed.