Originally posted by tim60 When I was young I often used ferries like that with cables across the river which were used in the drive system to go across the river and guild it to quick and easy docking at the landing point.
As I recall, the pictured ferry was also moved from one side of the river to the other by some form of mechanical cable mechanism. It would seem pointless and a waste of energy to use a motor-driven propeller for such a short distance. It hearkens back to the earliest ferries, a raft with a man who pulled it shore to shore with a rope, or even a rope pulled by the passengers. Low tech, slow, but with little traffic and not too much current, perfectly adequate.