If you look at most people’s BVI sailing itineraries, you’ll discover that they sail counter clockwise around the islands.
It is possible to sail either way, clockwise or counter clockwise, around Tortola.
However, there are often swells on the north side of Tortola. By sailing counter-clockwise, you make sure that you are sailing with the wind where the water is rough and sailing upwind in the more protected waters south of Tortola in the Sir Francis Drake channel.