I´m not sure it´s helpful for you, but I saw your posting and I live at the sea front in Ciutadella. Many boats part in front of my house. Not in the actual port. I doubt there is any charge for that. I´ve seen up to 30 boats there at a time at the busiest part of the season (Sant Joan). This is between the new commercial port and the small Castel Sant Nicolau. They have reconfigured the port in Ciutadella in the past year, there is space for many more boats, but I do not know the charges.