Chartered (adjective) can mean to have a charter or constitution, but it can also be used to describe a vehicle that has been rented, usually with the driver, for private tours.
The other day a friend asked me how long Gilligan’s trip was supposed to be. If you have no idea what I’m talking about, it’s okay; it just means you are young. (But if you ever need the answer for a trivia competition, it was a three hour tour.) Gilligan was working on a boat that was chartered. They may have ended up in uncharted waters, but because they were there, they were not unchartered waters.