The charter companies always recommend going upwind in the channel, and then doing the downwin Trellis Bay/Marina Cay to Jost run on the north side of the island
Perhaps that was one of the things glossed over during the briefing at Moorings. I spoke with a couple of people from Sunsail who have been amalgamated into the Moorings operation in Road town and it seems that it has now become too large and unwieldy. I hope you didn't try to take a mooring off Cooper's Island - that place rocks and rolls even in a dead calm.
I'm looking forward to going back this coming weekend!