Cost. This is cheap water. The shrimping trip has been advertised around thirty dollars a head, and a schooner sail is in a similar band rather than a luxury one. Private charters are the exception and are priced by the boat. Against a destination where a half-day tour starts at a hundred dollars a head, Biloxi is unusually accessible, and the reason is that nothing has to run far.
Season. The practical window is March to October. Schooner sailings and most small-operator trips thin out or stop in winter, not because the water is rough but because demand collapses and crews are seasonal. December to February is a fine time to be in Biloxi for casinos, museums and food. It is not the time to plan a boat.
Weather. Two things cancel trips here. From June through August, thunderstorms build inland in the late morning and come back over the coast in the afternoon, which is the argument for the earliest departure of the day. And from June through November this is a hurricane coast; September is the statistical peak and the month when a system in the Gulf three days out empties every dock on the Mississippi shoreline. Build flexibility into a September trip.
Wind. The Sound is shallow, so it does not need a lot of wind to turn choppy and unpleasant. A sailing boat needs some breeze and a small motor boat wants less, which is why two operators can make opposite decisions about the same afternoon.