I kept my boat at the most expensive marina in town. When I
sold my boat, mid season, the new owner sailed it away. Well, another boater had been eyeballing my
dock, and helped himself to it after my boat was gone, despite my having paid for the entire season. I spoke with the marina staff, who confirmed they had not given anyone permission to use my slip, especially as it was against marina policy and the obvious
insurance issues, and of course the fact that he was not paying for that (or any) slip. But I had
sold my boat, so I left it with the staff to deal with, and I just walked away.
I don't think you can protect a vacant slip or mooring. And any vessel having an
emergency should be free to take whatever slip or mooring necessary.
I once had a
medical emergency aboard my boat on a busy summer weekend. I proceeded with full sail and full
rpm to the nearest marina (POH for you locals) and went directly to the
service dock...there happened to be a first aid
trailer there (it was during CORK). Well, a large
power boat had been waiting for that
service dock, and began to let me know it over his blowhorn (loudspeaker). I replied to him, calmly, that I would move the boat after the ambulance departs. His offence turned to humility, but the distraction from the more important task at hand (attending to my injured crew) was already done. FWIW, the trip was ruined, as we all spent the rest of the weekend at the hospital. However, the crew
member recovered fully, to the best of my knowledge, as he never returned to my boat again.