Montserrat has an active volcano. Already has totally destroyed Montserrat’s largest city.
While travel agencies romanticize the Caribbean, the fact is that those people down there do not like us much. They just like our money. Since they depend on tourism, and for almost all their supplies to come from somewhere else, in a SHTF event they would likely be worse off than we here in CONUS. Pirate activity has also picked up a lot, especially in the western Caribbean.
Don’t mean to be a party pooper, but there is a lot of negatives regarding escaping difficult times on a boat. I feel sure you have considered all that.