Navigation Maps
About Navigation Charts
Nautical charts are published at different scales depending on the intended use. Harbor charts, published at scales of 1:50,000 and larger, are used for navigation and anchorage in harbors and small waterways. Coast charts are produced at scales from 1:50,000 to 1:150,000 for navigation in nearshore coastal areas and large harbors. General charts are produced at scales of 1:150,000 to 1:600,000, and are intended for offshore navigation, but contain enough detail to allow the use of visual navigation aids or depth soundings. Sailing Charts are produced at scales of 1:600,000 and smaller, for offshore sailing between distant coastal ports and for approaching the coast from the open water.
Many charts of the Great Lakes are produced and regularly updated by National Oceanic and Atmospheric Administration (NOAA). Twenty-four charts are published for areas of Lake Michigan, for example, at scales between 1:5,000 and 1:240,000. The entire lake is covered in a Mercator projection at a scale of 1:500,000. (Great Lakes charts were produced by the Army Corps of Engineers for many years, but this responsibility was transfered to NOAA in the 1980's.)
Obtaining Navigation Charts
NOAA publishes several series of navigation and nautical maps for coastal and offshore areas of the Great Lakes and oceans that border the country. The maps are most commonly used for marine navigation. Navigation and nautical charts contain a variety of information that pertains to lake and ocean bottom topography, geodetic coordinates, hazards to navigation, open water navigation, and approaches to harbors and ports.
NOAA also publishes charts specifically designed for use by small craft, including motorized pleasure boats and canoes. In Wisconsin, these charts cover Lake Winnebago and the lower Fox River to its mouth on Green Bay, and are produced in a strip chart format. Strip charts (in this case, bound in a book) are linear map sections that cover a specific stretch of lake or river.
Several NOAA publications relate to nautical charts; they include tide tables, tidal current and circulation charts, bathymetric maps, navigation data and regularly updated notices for mariners.
Navigation charts and small-craft charts are available directly from NOAA. In addition, local dealers including sporting goods shops and marinas often stock charts applicable to their region; in Wisconsin, most of these are along the shores of the Great Lakes.
For additional information or to order maps, charts, or publications contact the NOAA.
Navigation aids for the Mississippi River are maintained by the Army Corps of Engineers.
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