Map Projection, Positions, and Bearings
The Mercator projection is almost universally used in nautical charts. There are however some exceptions for very large or small scales where projections such as the gnomonic projection may be used. Since the Mercator projection is conformal, that is, bearings in the chart are identical to the corresponding angles in nature, bearings may be measured from the chart to be used at sea or plotted on the chart from measurements taken at sea.
Positions of places shown on the chart can be measured from the longitude and latitude scales on the borders of the chart, relative to a map datum such as WGS 84.
A bearing is the angle between the line joining the two points of interest and the line from one of the points to the north, such as a ship’s course or a compass reading to a landmark. On nautical charts, the top of the chart is always true north, rather than magnetic north, towards which a magnetic compass points. Most charts include a compass rose depicting the variation between magnetic and true north.
Read more about this topic: Nautical Chart
Famous quotes containing the words map and/or bearings:
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—Henry David Thoreau (1817–1862)
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