It is not valid. First of all, outside the US, a US Master's
license, not a six pac (OUPV) is necessary. Second, outside the US, you need an STCW. Third, if based in the
BVI, you need a
BVI Boatmaster's
license, which, however, can be gotten as a reciprocal to your Master's license.
None of this is obscure. You can contact the
Virgin Islands Shipping Registry at 1-284-468-2902 to satisfy your curiousity, but I actually thing it is the USCG that says the OUPV is invalid for international use. Both will tell you about the STCW.