PROPERTIES OF A MERCATOR CHART | ||
Scale | Correct on the Equator. Elsewhere increases as the secant of the latitude. Within 1% up to 8° from the Equator. |
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Orthomorphic | Yes. All charts used for navigation must be. | |
Graticule | Meridians are straight parallel lines, evenly spaced. Parallels are straight parallel lines with the space between them increasing with the secant of the latitude. |
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Shapes | Reasonably correct over small areas. Distortion over large areas, especially at high latitudes. |
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Chart Convergence | Zero everywhere. Correct at the Equator. Constant across the chart. |
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Rhumb lines | Straight lines Always! Everywhere! | |
Great circles | Equator and meridians are straight lines (because they are also rhumb lines). All other great circles - curves, with a track nearer the Pole (or concave to the Equator). |
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