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A 1976 United States NOAA chart of part of Puerto Rico A nautical chart of the Warnemünde harbor shown on OpenSeaMap. A nautical chart or hydrographic chart is a graphic representation of a sea region or water body and adjacent coasts or banks.
Graphical and textual descriptions of navigational light sequences and colours are displayed on nautical charts and in Light Lists with the chart symbol for a lighthouse, lightvessel, buoy or sea mark with a light on it. Different lights use different colours, frequencies and light patterns, so mariners can identify which light they are seeing. [1]
The nautical star indicates geographic north in compass roses on nautical charts. Modern nautical charts use the star to indicate true north on the outer of the two compass circles of a compass rose, symbolizing the North Star. [1] [2] The United States Coast and Geodetic Survey started using this symbol in its double-circle compass roses ...
The charts are published "in accordance with Interagency Air Cartographic Committee specifications and agreements, approved by the Department of Defense and the Federal Aviation Administration". The legend of an aeronautical chart lists many of the symbols, colors and codes used to convey information to the map reader.
An Electronic Navigational Chart (ENC) is a digital representation of a real-world geographical area for the purpose of Marine navigation.Real-world objects and areas of navigational significance, or to a lesser degree - informational significance, are portrayed through Raster facsimiles of traditional paper charts; or more commonly through vector images, which are able to scale their relative ...
The charts are stored in BSB format. "[The BSB file format] is a proprietary format of BSB Electronic Charts, LLP (bought by MapTech, Inc.)." [1] Image manipulation tools such as GDAL can read the image information, but there also is georeferenced data in the navigational charts.
It is therefore important to consult appropriate charts to determine their meaning in each location. They are also known as fairway buoys and clear water buoys. They are recognisable by their red-and-white vertical stripes and commonly bear a top sign in shape of a red ball.
A chart datum is the water level surface serving as origin of depths displayed on a nautical chart and for reporting and predicting tide heights. A chart datum is generally derived from some tidal phase, in which case it is also known as a tidal datum. [1] Common chart datums are lowest astronomical tide (LAT) [1] and mean lower low water (MLLW).