Hi Wolf and welcome back,
Having been involved peripherally with the sail charter
business in the Caribbean
and with a good friend that managed a charter
base in Tortola I can say that without a doubt the number one requirement to get started is to demonstrate long term dedication and commitment to the career. Down island the stream of day dreamers and wannabe boat captains is constant, almost every day brings a new batch walking the docks.
So the first job you will have will be to prove you're really going to there for the long haul.
Next you will have to show you are willing to show up on time, regularly and work.
Once you get your foot in the door and you are in the business for a while it will just be a matter of building your skills and connections and you are on your way. It can be done. My cousin married a guy who started as a deck
hand on sailboats and worked his way up to capt on 180' Feadship. Now runs his own consulting business.