Maps and Charts of the Fifteenth Century

 Mariners during the 15th century relied on charts called "portolans" to assist them on their voyages. Portolan comes from the Italian word portolani, which were medieval pilot books. The portolans contained maps of coastlines, locations of harbors, river mouths, and manmade features visible from the sea. They were a compilation of centuries of seafarer observations. As sailors' skills improved and the use of the compass was more widespread, portolans improved in accuracy.

Portuguese chartmakers added the meridian line, a point useful for latitude sailing as well as for navigating solely by compass. A geographic feature could now be located through the use of its distance in degree of latitude from a ship's point of departure.

The use of latitude and longitude was understood since the time of Ptolemy in the second century A.D. He assigned coordinates to place names. The use of latitude and longitude posed difficulties while sailing on the high seas.

Portuguese Explorers | Portuguese Ships | Navigation Methods | 15th-Century Maps & Charts