How accurate are nautical charts?

Charts will provide more information on “zone of confidence”

It is a major challenge – some might say an impossibility – to keep all thousand U.S. nautical charts up to date. But exactly how out of date is the chart data? Chart users will get a better idea now that Coast Survey is gradually rolling out a new chart feature called the zone of confidence, or “ZOC” box. It will replace the source diagram that is currently on large-scale charts. Source diagrams, and now the improved ZOC, help mariners assess hydrographic survey data and the associated level of risk to navigate in a particular area.

The first charts to show the new ZOC box are 18622, 18682, 18754, and 11328. They were released on April 7.

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