The first record of boats large enough to carry goods for trade is around 3500 B.C. and this would mark the birth of the art of navigation. Early navigators generaly stayed close to shore and navigated by sight of landmarks or visible land characteristics. Usually they traveled by day and sought a calm harbor or anchorage at night. They did not have charts but lists of directions, similar to today’s cruising guides.
The first ocean voyages were dramatic – a vessel blown off course by a sudden storm or error by the helmsman could destroy the ship and crew. However, Vikings regularly sailed to Iceland and Greenland between 900 and 1000AD, apparently using only the sun, stars and wind as their guide.
Early navigators had to be creative in compensating for their lack of technology. Viking explorer Floki Vilgjerdarsson, credited with the discovery of Iceland, carried aboard a cage of ravens. When he thought land should be near, he would release one of the birds. If it circled the boat without purpose, land was not near, but if it took off in a certain direction, the boat followed, knowing the bird was headed toward land.
One of the earliest man-made navigation tools was the mariner’s compass, an early form of the magnetic compass (c.13th Century). Initially used only when the weather obscured the sun or the North Star, these first compasses were very crude. The navigator would rub an iron needle against a lodestone, stick it in a piece of straw and float it in a bowl of water. The needle would point in a northerly direction. Early mariners found the compass inconsistent – most likely because they did not understand that it pointed to the magnetic north pole, not true north. At the time, they could not explain these variations and could not put much trust in the readings when navigating an unknown area.
At this time, mariners began to realize that maps would be helpful and began keeping detailed records of their voyages that land-based mapmakers used to create the first nautical charts called Portolan Charts (c. 13th Century).
The charts, created on sheepskin or goatskin, were rare and expensive and often kept secret so that competing mariners would not have access to this knowledge. What they lacked in accuracy they made up for in beauty, which you can review by visiting Geographicus. Lands and ports on the chart were highly decorated with depictions of buildings and flags.
The size of lands on charts were more a reflection of their importance to trade routes than their actual geographical size and, of course were not very accurate. The charts did not have latitude or longitude lines but did have compass roses indicating bearings between major ports.