After I learned to sail, I discovered the white arrow at the bottom left of the map which helps when the wind is in the wrong direction (time to use the rudder as an oar). The white arrow on the map still shows the wind direction even when there is no water in sight. If the wind is blowing from the Troll toward me, I can get really close to him to take him down. If the wind blows from me toward the Troll, it's time to get out of there in a big hurry.