This device was used in navigation. A kamal was made from a rectangle of wood with rope through the center. The rope was knotted at various lengths depicting specific ports. Taking a sighting on a pole star during the evening allowed a navigator to determine which direction they were currently sailing or if they were sailing along the same latitude of a port knotted on the string.
Kamals could be purchased at any port city in Zakhara for less than one piece of gold.