seeking a touring /turtle observation boat/business please!

First, for a boat that carries more than 6 paying guests, you or your captain will need a Master captains license.
You first get a 6 Pack captains license that will allow you to take up to 6 guests.

A vessel that carries more than six passengers must pass the USCG Inspected Vessel regulations - CFR 46 - the Captain must have a Masters license as mentioned above - buying an existing Inspected Vessel would be the best way to proceed whether it is purchased here or in the States and shipped down.
There is a PM [personal message] option availableon the forum and is probably preferable to posting an email address on a public forum.
As an owner operated business touring and turtle observing may be a bit limiting but include snorkeling and offering the inevitable but popular BVI bar junket could make it financially viable. Of course International voyages add another layer of regulation and if you can specialize in Domestic charters and survive it will be easier. Good Luck - it is great to spend the day working on the water - make sure the boat has plenty of shade available at least for the Captain.

Regarding the turtle observation-- turtles are not very interesting to look at from a boat, in my opinion. They look like brown dinner plates, stick their heads out of the water, breathe, maybe float a bit and then go back under. Its not like whale watching. If you wanted to "market" turtle-watching, you'd have to have an inwater component, and turtles, nor any other animal are a guaranteed sight. Additionally, all the USVI sea turtles are endangered species which means you have to stay a certain distance away from them in order not to influence their behavior and not touch them. And to do anything else with them, you need permits from DPNR (and permits are typically only for research/education purposes, not recreation) AND NOAA (if anything you are doing with them is in the water). So I'm not sure that a "turtle-watching" strategy would be the best option...

Snorkeling turtle sight seeing sounds much more fun. I've gone on a few sailing trips from STT Compass Point to STJ Honeymoon for a snorkel over there. They offered cheap champagne and rum punch after the snorkel for the trip back. It seemed a pretty simple set up, but it was so much fun! A friend of mine works on one, so I got the local discount! Such a nice way to spend half a day.