May 5, 2004

Q: What are nautical charts, and where can they be obtained for specific U.S. coastal areas?

A: Nautical Charts are graphic portrayals of the marine environment. In addition to providing the most basic elements (i.e., a schematic layout of a Coast Survey chart), these charts are working documents used by the mariner both as a "road map" and worksheet required for safe navigation. In conjunction with supplemental navigational aids, they are used to lay out courses and navigate ships by the shortest and most economically safe route. Charts show the nature and form of the coast, the depths of the water and general character and configuration of the sea bottom, locations of dangers to navigation, the rise and fall of the tides, locations of man-made aids to navigation and the characteristics of the Earth's magnetism.

In addition to the traditional paper product, charts are also available in both raster (a georeferenced, digital picture of a paper chart, which can be used in a raster chart system) and vector format (an electronic navigational chart).

One publication which provides a wealth of technical information concerning the structure, layout and construction of a nautical chart is the Nautical Chart User's Manual. This publication covers basic topographic and hydrographic features, aids to navigation, chart symbols, miscellaneous other charting features and supplemental information.

Today, nautical charts are used by the Departments of Defense and Transportation, state and local governments, commercial shippers, the fishing industry and recreational boaters throughout the United States. Navigational Charts and Coast Pilots are integral components necessary for the safety of life and property and safe and efficient navigation while transiting United States and territorial waterways. Federal law requires all ships in excess of 1,600 gross tons to have and use current editions of these navigation products. Charts and hydrographic surveys are also used by environmental groups, academia and coastal zone planners.

The NOAA Office of Coast Survey, a division of the NOAA National Ocean Service, is responsible for publishing and maintaining nautical charts for the United States and its territories, while the Federal Aviation Administration does the same for aeronautical charts and flight information. The National Imagery and Mapping Agency (formerly Defense Mapping Agency and other organizations) is the U.S. agency responsible for publishing and maintaining nautical and aeronautical charts for the rest of the world.