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However, if the map is marked with an accurate and finely spaced latitude scale from which the latitude may be read directly—as is the case for the Mercator 1569 world map (sheets 3, 9, 15) and all subsequent nautical charts—the meridian distance between two latitudes φ 1 and φ 2 is simply
If a navigator is west of the agonic line, then the variation is eastward; the Magnetic North Pole appears to the east of the Geographic North Pole. The farther the navigator is from the agonic line, the greater the variation. The local magnetic variation is indicated on NOAA nautical charts at the center of the compass rose. The magnetic ...
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.
The Medieval and Early Modern Nautical Chart: Birth, Evolution and Use, Lisbon-based ERC-funded academic project. They develop and maintain the MEDEA-CHART Database, a sophisticated search engine and aggregator of early nautical charts data. Online version of Chart No.1 with "Symbols, Abbreviations and Terms" used in nautical charts
In the past, the gnomonic projection was widely used for navigation charts, and also for polar charts. [29] Since the late 1970s, all charts at a scale of 1:50,000 or larger have used the transverse Mercator projection, [30] which is the projection used for the Ordnance Survey National Grid.
Today electronic computers or calculators are used. Other traditional aids used included tables (trigonometric, logarithms, etc.) and slide rules. Dividers used for measuring lengths of lines and approximate lengths of non-linear paths on a chart. Nautical almanac used to determine the position in the sky of a celestial body after a sight has ...
Navigation that follows a rhumb line — that is, all meridians are cut at the same angle. On a nautical chart following the Mercator projection, a loxodromic is represented by a straight line. This type of navigation is useful for not too long distances, as it allows the course to remain steady, [16] but it does not offer the shortest distance.