Brewers Bay is an absolutely beautiful cove along the north side of Tortola. It features a magnificent beach and some great snorkeling. There is a reef that comes off of both shores and one directly out from the center of the bay.
There are underwater cables in Brewers Bay which prevent this from being available as an anchorage. In addition, the northern swells can make Brewers Bay a bit bumpy when the swell is up.
Due to these factors, especially the tricky manuvering due to the coral, most charter companies tend to ask their bare boat charters to stay out of Brewers.