If your "significant sailing experience" is all in small daysailers then I would agree with those who say, take the class. I would suggest one of the classes where you live on the boat. This type of class is offered by Sunsail as well as The Bitter End.

If you have sailing experience in boats larger than 30' LOA, with a diesel auxiliary, though, and especially if you have any experience anchoring or picking up a mooring, then I have to agree with Subaqua. With that kind of experience you do not need a class, or any certification, in order to charter in the BVI. Nothing wrong with taking a class, of course, if you want to, but it would not be a requirement.

Good luck.