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Online version of Chart No.1 with "Symbols, Abbreviations and Terms" used in nautical charts; Portolan Chart of Gabriel de Vallseca, 1439; The short film "Reading Charts (April 6, 1999)" is available for free viewing and download at the Internet Archive. Nautical charts available online (Nautical Free) Online Nautical Charts Viewer
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
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 ...
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.
For many centuries, a hydrographic survey required the use of lead lines – ropes or lines with depth markings attached to lead weights to make one end sink to the bottom when lowered over the side of a ship or boat – and sounding poles, which were poles with depth markings which could be thrust over the side until they touched bottom.
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.
OpenSeaMap is a software project collecting freely usable nautical information and geospatial data to create a worldwide nautical chart. This chart is available on the OpenSeaMap website, and can also be downloaded for use as an electronic chart for offline applications. [1] The project is part of OpenStreetMap. OpenSeaMap is part of the ...