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On nautical charts, the top of the chart is always true north, rather than magnetic north, towards which a compass points. Most charts include a compass rose depicting the variation between magnetic and true north. However, the use of the Mercator projection has drawbacks. This projection shows the lines of longitude as parallel.
The General Bathymetric Chart of the Oceans (GEBCO) is a publicly available bathymetric chart of the world's oceans. The project was conceived with the aim of preparing a global series of charts showing the general shape of the seafloor. Over the years it has become a reference map of the bathymetry of the world's oceans for scientists and others.
[8]: 10 [9] The most common chart size was early established as the "Double-elephant", about 39 X 25.5 inches, and this has continued to be the case. [10] Chart design gradually simplified over the years, with less detail on land, focusing on features visible to the mariner. Contours were increasingly used for hills instead of hatching.
A tidal atlas or a tidal stream atlas is used to predict the direction and speed of tidal currents. A tidal atlas usually consists of a set of 12 or 13 diagrams, one for each hour of the tidal cycle, for a coastal region. Each diagram uses arrows to indicate the direction of the flow at that time.
Before the advent of nautical charts in the 14th century, navigation at sea relied on the accumulated knowledge of navigators and pilots.Plotting a course at sea required knowing the direction and distance between point A and point B. Knowledge of where places lay relative to each other was acquired by mariners during their long experience at sea.
The Cornaro Atlas (Egerton MS 73) is an extensive Venetian collection (c. 1489) of nautical charts and tracts, currently held in the Egerton Collection of manuscripts of the British Library. Background
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A large number of boats of all types were built on these waters, powered by various means, including steam, gasoline, and diesel engines. This index will attempt to track only vessels over 30 tons built before 1920, with exceptions where a vessel appears to be of more interest, due to an available on-line image or otherwise.