UPDATE: my mistake - br3nt is right. The MMSI is associated with the INDIVIDUAL and not the vessel, as I indicated in my previous post. The MMSI database entry, however, does identify the vessel, hailing port and emergency points of contact.
So, while you can edit the MMSI Database to indicate that you and your MMSI registered radio
are changing vessels, it still seems like a pain to have to do this if you go sailing on a friend's boat, and want to bring your handheld VHF
I hope this helps.