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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
A sailor and a man on shore, both sounding the depth with a line. Depth sounding, often simply called sounding, is measuring the depth of a body of water. Data taken from soundings are used in bathymetry to make maps of the floor of a body of water, such as the seabed topography. Soundings were traditionally shown on nautical charts in fathoms and
Nautical mile: Length: Rhumb: Angle: The angle between two successive points of the thirty-two point compass (11 degrees 15 minutes) (rare) [1] Shackle: Length: Before 1949, 12.5 fathoms; later 15 fathoms. [2] Toise: Length: Toise was also used for measures of area and volume Twenty-foot equivalent unit or TEU: Volume: Used in connection with ...
A fathom line or fathom curve, a usually sinuous line on a nautical chart, joins all points having the same depth of water, thereby indicating the contour of the ocean floor. [24] Some extensive flat areas of the sea bottom with constant depth are known by their fathom number, like the Broad Fourteens or the Long Forties, both in the North Sea.
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).
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 ...
Between 1906 and 1916, Heck expanded the capability of wire-drag systems from a relatively limited area to sweeps covering channels 2 to 3 nautical miles (3.7 to 5.6 km; 2.3 to 3.5 mi) in width. [15] The wire-drag technique was a major contribution to hydrographic surveying during much of the rest of the 20th century.
Thus the chart coloration gave a clear indication to users as to whether they were using a chart with depths in fathoms or feet. While depths and heights were in metres, the nautical mile continued to be an international standard. Derived from the length of 1 minute of latitude, it is defined as 1852 metres. [12] [13] [14] [15]