You will need the same stuff you do in Florida
.... and some good luck..
Not to be a wet rag but you may find operating a Day Charter
in the USVI to be lots more interesting, it really isn't much different than from any typical Florida
location as far as the business end goes... except COST..
Almost everything is about 10% to 20% higher. To have a good shot at clients you will have to mate up to some of the resorts and hotels which as an "outsider" you will have initial resistance. The Big Cruise
Boat contacts are far harder to break into and are expensive as they generally require a kick back arrangement in addition to client discounts. I know one guy who operates out of Crown Bay that says he only breaks even half the time and is on both sides about equal amounts. A few rain days turns him into a fisherman's hand for cash flow.
It would be more difficult to operate in BVI but the number of potential clients is probably marginally better. You will probably have to show you will employ one or two locals to get a work permit and license to operate a charter boat. Not whole people but on a fractional basis if you understand GEO politics.
A good location is key... but few exist that are reasonable priced. Some like Red Hook may not be too far from average price
but due to the open end to the East are really rough and rollie the entire Prime Season from November to March. It's bad to have people sea sick walking down the floating dock
for your boat at night, or when ever it is not obviously occupied is another big consideration and location has much to do with that.
If you decide to go into the BVI, you will need Charter Boat license in the BVI or you could loose your boat. One Captain
just had a $7,000 fine for bringing clients in as "Friends" and he was happy it was just a fine.
Building up a client base that would sustain your cost will probably not be easy when you start up, so have sufficient cash to hold you over for a year or so.