Why not pump the 'water' out of the bulk into a separate containment vessel. This way the ship's crew could neutralise the risk without reducing the weight of their cargo. When unloading they can give back the 'water' component of the cargo separately. So the weight of the cargo is basically unchanged.
Because the water would need to be separated from the sand grains. The "water" in the sand is very little: it's more akin to damp sand we're talking about, or in the "wettest" case mud.
Drying that would require a lot of area, effort, and sun, or some type of oven. Any method of making sand drier costs orders of magnitutde more than the sand itself.
