I've found that anchoring or mooring outside of Spanish Town can be surprisingly rough and rolly considering it's location. I have anchored between the reefs at Savannah (it is a bigger area than the satellite images or the maps would lead one to believe) and it was incredibly protected; but my worry was always what I could do if a major CuNim would hit at night. So my recourse has always been to just motor up into the wind and into the North Sound with all of its good anchorages and mooring fields - nothing is better protected in the BVI than the North Sound. Trellis is full of mooring balls, so anchoring is not an option - if the mooring balls are all taken then Marina Cay is the next open alternative and if all those mooring balls are taken there is still a large area of 30' deep anchoring available... But when anchoring there one is subject to the wakes of all the boat traffic during day and night.