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Seymour Narrows is notable also because the flowing current can be sufficiently turbulent to realize a Reynolds number of about , i.e. one hundred million, which is possibly the largest Reynolds number regularly attained in natural water channels on Earth (the current speed is about 8 m/s, 26 ft/s, the nominal depth about 100 m, 330 ft). [4]
Tide tables, sometimes called tide charts, are used for tidal prediction and show the daily times and levels of high and low tides, usually for a particular location. [1] Tide heights at intermediate times (between high and low water) can be approximated by using the rule of twelfths or more accurately calculated by using a published tidal ...
Depending on the scale of the chart, it may show depths of water and heights of land , natural features of the seabed, details of the coastline, navigational hazards, locations of natural and human-made aids to navigation, information on tides and currents, local details of the Earth's magnetic field, and human-made structures such as harbours ...
Each day, tides force large amounts of seawater through the narrows—760,000,000 m 3 (200 × 10 ^ 9 US gal) of water on a 3 m (9.8 ft) tide. The difference in water levels on either side of the rapids can exceed 2 m (6 ft 7 in) in height. Current speeds can exceed 16 knots (30 km/h; 18 mph), [2] up to 17.68 kn (32.74 km/h; 20.35 mph). [3]
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).
The national chart folio consists of 950 paper charts, 541 S-57 vector Electronic Navigation Charts and 651 raster charts in the BSB format. CHS produces and maintains seven volumes of Tides and Water Levels books, 25 Sailing Directions books, and prints and distributes a number of publications such as the Annual Notices to Mariners and Radio ...
CHS is a world leader in the adoption of hydrographic survey technology, as well as in research and development. With responsibility for charting the world's longest coastline (243,792 kilometres) as well as 6.55 million square kilometres of continental shelf and territorial waters (second largest in the world), including extensive inland waterways such as the St. Lawrence Seaway, CHS ...
The water stops rising, reaching a local maximum called high tide. Sea level falls over several hours, revealing the intertidal zone; ebb tide. Oscillating currents produced by tides are known as tidal streams or tidal currents. The moment that the tidal current ceases is called slack water or slack tide. The tide then reverses direction and is ...