The USVI are a special and complicated case for charter boats. Bareboating I think that the flag doesn't matter, but chartered boats the crew cannot be US citizen but foreigners with the correct visas and that would be legal.
@Zanshin - I think the opposite may be the case. US flagged boats with US crew are going to have an easier time in the USVIs. I think captain also has to have a US charter license....might be easier to get for 6 or fewer PAX. That's what I recall after checking into it a few years ago. The rules and regs might be different now.
