We were in Tortola a few years ago on a cruise and just took a cab over to the beach for the afternoon. I have no idea what the name of the beach was but we were the only folks on this very long horseshoe shaped beach that was beautiful- a few miles long. We made arrangements with the cab driver to pick us up at a designated time and found a little hotel on the beach with a pool that served lunch. It was a great day. This time I think we will go to the Baths and take the Ferry (not the excursion through the ship).
We will be on your cruise on the 11th too. However, I don't think we will be in Tortola until 11 PM. Have not gotten tickets yet but don't think that was the time I noted.
Do you know what time is listed on your tickets for us to leave Tortola?