portolan
/ˈpɔːtəlan
/(also portolano /ˌpɔːtəˈlɑːnəʊ/)
noun (plural portolans or portolanos) historical
A book of sailing directions with charts and descriptions of harbours and coasts.From early times, charts called portolans (harbor guides) were available to provide details required by the coastline-hugging sailor - depth of the water, location of treacherous rocks, special landmarks, et cetera....
- In its purest form, the portolan chart was a highly functional tool for navigation whether in the contained arena of the Mediterranean or later in the open oceans of the world.
- On an oceanic voyage, however, especially at higher latitudes, the converging meridians on the physical globe conflicted with the parallel meridians shown on the traditional portolan chart.
Origin
Mid 19th century: from Italian portolano, from porto 'harbour'.