The Kamal

Arab sailors traded along the coasts of Arabia, East Africa, India and Southeast Asia. They travelled the Mediterranean as well.

The instrument they invented to navigate, besides the stars, was called the Kamal. It was a kind of sextant. In 1980-81 Tim Severin used one to make a lengthy sea journey and found the Kamal accurate within 40km, a tiny margin of error.

The Kamal is simple: A wooden rectangle attached to a knotted string. It was well ahead of other navigational instruments that came later.