Casting this spell on a water vessel up to the size of a small sailing ship transforms it into a vessel capable of sailing on sand as easily as water. The vessel still needs a trained crew and relies on wind or oars for propulsion, but it moves at its normal speed across sand instead of water for the duration of the spell. It can sail only over sand, not soil or solid rock. For the duration of the spell, the vessel doesn't float; it must be beached or resting on the bottom of a body of water (partially drawn up onto a beach, for example) when the spell is cast, or it sinks into the water.