From YPPedia
A selection of winds at the edge of a sea battle board.

Winds, also known as streams, are tiles that move ships in sea battle one square to leeward; that is, in the direction the wind blows towards. The three wind squares near the center of the picture will move a ship down, towards the rocks in the bottom right-hand corner. If the navigator does not allow for the effect of wind, it can result in the ship ramming a rock, the border, or another ship—damaging the ship. Wise navigators use the winds to move quickly or for movements otherwise not possible.

When wind is involved in a move, the order of events is: