Dead Calm

You stifle the winds around one ship or sailing vessel of your choice within range. For the duration of the spell, there is not enough wind to propel and watercraft within a 1/2 mile radius of the target ship. A control weather or similar spell of 5th level or higher can dispel this affect, and the spell cannot calm the raging winds of a gale or storm.

At Higher Levels. When you cast this spell using a spell slot of 6th level, you can extend the spell's duration by one hour for each slot level above 5th.