NAUTICAL CHARTS have been in use since the end of the 13th century, the invention of the magnetic compass in the 12th century seems to have been the catalyst for the development of charts. It is only in the last 150 or so years that they have become accurate and generally available.
Medieval charts were just artistic impressions of what people thought a coastline was like, often with colourful pictures suggesting the presence of dragons and other awful sea monsters lurking just over the distant horizon.