What is a nautical chart?
To someone who has not been at the helm of a vessel, a nautical chart might look like nothing more than an oddly detailed water map. To a boater, a nautical chart is much more than a “road map” of the water. Instead of roads it details water areas, ports, and coast lines; it also includes information about depth of the sea floor, obstructions, restricted areas, recommended routes, and aids to navigation such as lights and buoys. The main purpose of a nautical chart is to give boaters up-to-date information to avoid grounding or traveling in restricted waters, and to navigate safely for themselves and the vessels around them.
Where can I find current navigational charts?
The United States Office of Coast Survey (USCS) has been producing nautical charts for more than 200 years, ever since President Thomas Jefferson asked for a survey of the coast in 1807. The USCS has made and maintains over 1,000 charts at varying levels of detail that cover all of the U.S. and U.S. territory coastal waters and the Great Lakes. These charts are conveniently available online for viewing and downloading. They are free of charge and regularly updated.
To find a particular nautical chart, start at the NOAA (National Oceanic and Atmospheric Administration) Charts for U.S. Waters Online Chart Viewer. From the Online Chart Viewer you can select a region to view or navigate using the Graphical Catalog. Also available are BookletCharts for printing to help recreational boaters locate themselves on the water.
The Graphical Catalog shows the outlines of charts that are available on a basic geographical map. As you click on a chart, information to the right of the map show you the coordinates for the selected point as well as the Chart number, panel number, and scale of the chart selected. When you zoom in on an area, more detailed charts with larger scales become available to select. The name of each nautical chart is listed below the map as a Panel Title, as well as the date of the most current edition. Each nautical chart is available to be viewed online, downloaded as an RNC (Raster Navigational Chart), or ordered as a paper chart. In addition to finding nautical charts by browsing the map, you can also find nautical charts by entering the coordinates of the location you are seeking.
In addition to these current nautical charts you can also find nautical charts to view at the library by searching for cruising atlas in the online catalog.
A compass rose shows both the true North in the outer circle and the magnetic North in the inner circle, and the difference between the two is called the magnetic variation. It is important to always use the compass rose nearest the area for which you are plotting directions. For detailed guidance on how to read a nautical chart, check out How to Read a Nautical Chart by Nigel Calder or Chapman Nautical Chart No. 1 from the U.S. Coast Guard.
What did nautical charts and maritime maps look like in the past?
In addition to modern nautical charts, the USCS also has beautiful and detailed historical maps and charts available on their website. Other recommended historical resources are The Charting of the Oceans by Peter Whitfield (an overview of Europe’s charting history) and Soundings: The Story of the Remarkable Woman Who Mapped the Ocean Floor by Hali Felt (in the 1950s, Marie Tharp turned her husband’s records of sonar pings measuring the ocean’s depth into illuminating maps of the ocean floor that proved for the first time the theory of continental drift).
Finding these charts can be complicated! If you have any questions, do not hesitate to Ask a Librarian.
The NOAA website includes this note: Use the official, full scale NOAA nautical chart for real navigation whenever possible. These are available from authorized NOAA nautical chart sales agents. Screen captures of the on-line viewable charts available here [on NOAA's online chart viewer] do NOT fulfill chart carriage requirements for regulated commercial vessels under Titles 33 and 46 of the Code of Federal Regulations.