I read some sources that transport by boat over European rivers developed already in the early medieval period, ie after having developed ships with low draft as well as the invention of a controllable rudder. However, boats were mostly used for transport of goods. Transport of passengers developed much later, ie late medieval period (1350-1500), despite there being many travelers, such as merchants and pilgrims.
- Why did passenger transport over water take off so much later? Was it because the passenger numbers were too low to make it profitable?
- In case of combined goods and passengers service, were passengers convenienced in any way, such as benches to sit on, awnings against sun/rain?
- The upstream trip would presumably require the use of a sail? Would that mean that the height of masts were such that the boats could sail under bridges? If not, what would be a common mode of propulsion?
Here are a few images that show various ship types from the late medieval period, albeit none specifically for people transport, other than a row boat: shipno1, shipno2, shipno3, shipno4, shipno5, shipno6
Then there is the Ulmer Schachtel, as used in Bavaria (Danube), but designed for goods transport, not specifically people. It states "Ships from Bavaria did also sail upstream to Ulm, but the people of Ulm had no ships of their own at that point." and "done by raft".
Also this source mostly discusses goods transport and makes the point that "most inland Utrecht-type ships must have been towed, poled, or oared."