New Information Added to Charts
New data for chart updates is categorized as being either "critical" or "routine". Critical data includes any changes that may pose a danger to navigation and that mariners should be informed of as soon as possible. This may include newly discovered rocks, wrecks, shoals, or other dangers to navigation, as well as changes in the positions or characteristics of aids to navigation (buoys, beacons, and lights).
These critical corrections are published by the U.S. Coast Guard in Local Notices to Mariners and mariners must apply these changes by hand to their paper nautical charts to keep them up to date.
NOAA applies critical corrections to its electronic navigational chart (NOAA ENC®) product and these updates are released as ENC revision files. NOAA also updates its traditional paper nautical charts and related raster chart format products with critical corrections. Any new paper chart purchased and any raster chart downloaded will have all critical corrections already applied as of the week the chart is purchased or downloaded.
All non-critical data is categorized as "routine." This includes the results of ordinary hydrographic and shoreline surveys, which can be extensive.
Routine source data is ONLY applied to NOAA ENCs and not to paper and raster nautical charts. Traditional NOAA nautical charts and associated raster chart products are being discontinued. See more information about the sunsetting of these products at Farewell to Traditional Nautical Charts. Mariners are encouraged to use NOAA ENCs for the most up-to-date information.
Any specific dangers revealed during routine surveys or the application of other routine data are extracted from the data and classified as critical corrections to be applied to all products.