Friday, June 19th, 2009. Symbols and abbreviations.
Someday when planning a trip in an unfamiliar area unusual abbreviations on the seabed or on a beach considered for an escape route, may draw our attention and the chart might offer little help to understand a complex traffic separations scheme.
For instance it took me long to figure out that the initials DW in the diagram above stand por deep water, and I could have spent ages to learn that the arrows with discontinuous traces mark the recommended direction of traffic flow for ships that do not need a deep water route.
Never would I have formed the conjecture that a bracket under a wreck (Wk) meant as in the illustration above, means that its last known depth was measured by having been swept by wire drag or diver.
No way neither to have guessed that S/M stands for two layers of sand over mud, or that vard. cn. ml. stands for a rare seabed formed by varied cinders and marls. On the other hand I had already learned that Br stands for breakers, and abbreviation usually close to ddangerous underwater rocks or reef of known depth, or to rocks that covers and uncover at certain height above chart datum.
Clearly much of the information contained on charts is shown by symbols and abbreviations that sometimes are not the ordinary. The United Kingdom Hydrographic Office details them for the Admiralty charts - “trusted by mariners worlwide” - in a convenient A4 booklet known as chart 50011 because it was originally produced in chart format, descriptively titled Symbols and Abbreviations used on Admiralty Paper Charts whose latest edition is the fourth, printed on October 16th, 2008.
As for the United States, nautical symbols for the excellent charts both from the National Oceanic and Atmospheric Administration and the National Geospatial-Intelligence Agency are explained in a reference publication known as Chart No. 1. No longer available in print, the current tenth edition dated in November 1997 of Chart No.1 is available as a download.












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