How accurate are your nautical charts? - The Ultimate Guide
by Sail-World Cruising on 17 Aug 2010
Is this chart accurate? SW
How accurate are the nautical charts that you use when going sailing? Do you really know how much faith can be placed in them?
Unfortunately, the answer is quite complex – far more complex than simply saying one chart is accurate whilst another is not.
All charts, whether paper or electronic, contain data which varies in quality due to the age and accuracy of individual surveys.
In general, remote areas away from shipping routes tend to be less well surveyed, and less frequently, while areas of high commercial traffic are re-surveyed frequently to very high levels of accuracy, particularly where under-keel clearances are small.
It is quite accurate to consider a chart as a jigsaw of individual surveys pieced together to form a single image.
Having the necessary skills to determine how much confidence should be placed in the surveys which combine to form a chart should be essential for any sailor venturing into unfamiliar waters.
The Australian Hydrographic Service has a valuable guide as to the accuracy and reliability of charts which any skipper or navigator of a sailing vessel should be familiar with.
It contains both explanations and examples intended to assist mariners in vessels of all sizes to determine how much confidence they should place in charts.
To access this information, a comprehensive explanation by Mike Prince, Director of Charting, Australian Hydrographic Service, click http://www.hydro.gov.au/important-info/accuracy_and_reliability_of_charts.pdf!here
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