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The first recorded evidence of water depth measurements are from Ancient Egypt over 3000 years ago. [3] Bathymetry has various uses including the production of bathymetric charts to guide vessels and identify underwater hazards, the study of marine life near the floor of water bodies , coastline analysis and ocean dynamics , including ...
Depths which have been measured are indicated by the numbers shown on the chart. Depths on charts published in most parts of the world use metres. Older charts, as well as those published by the United States government, may use feet or fathoms. Depth contour lines show the shape of underwater relief. Coloured areas of the sea emphasise shallow ...
Bathymetric charts showcase depth using a series of lines and points at equal intervals, called depth contours or isobaths (a type of contour line). A closed shape with increasingly smaller shapes inside of it can indicate an ocean trench or a seamount, or underwater mountain, depending on whether the depths increase or decrease going inward.
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
The process was labor-intensive and time-consuming and, although each individual depth measurement could be accurate, even a thorough survey as a practical matter could include only a limited number of sounding measurements relative to the area being surveyed, inevitably leaving gaps in coverage between soundings. [12]
Until early in the 20th century, it was the unit used to measure the depth of mines (mineral extraction) in the United Kingdom. [30] Miners also use it as a unit of area equal to 6 feet square (3.34 m 2) in the plane of a vein. [2] In Britain, it can mean the quantity of wood in a pile of any length measuring 6 feet (1.8 m) square in cross ...
Deadweight tonnage (DWT) is a measure of how much weight a ship can carry. [1] [2] [3] It is the sum of the weights of cargo, fuel, fresh water, ballast water, provisions, passengers, and crew. [1] Draft or draught (d) or (T) – The vertical distance from the bottom of the keel to the waterline. Used mainly to determine the minimum water depth ...
Measurements can be made using a variety of instruments. Vertical position relative to the surface, also known as depth measurement, may use: Depth gauges (using pressure as a proxy) Dive computers (using pressure as a proxy) Measuring tapes (direct linear measurement) Pneumofathometers (using pressure as a proxy)