I noticed something a couple of weeks back. When you exit Providence claim on boat you are still technically considered in Providence as long as you don't exist your boat. When you come back to Providence in boat you are still technically considered out of Providence until you exit the boat. That, or the message "You've entered in Providence" is bugged and only show when you exit the boat or whatever. That might by why your boat was destroyed beneath you.
It's mere speculations though.