ENC data also has additional information that can be accessed by a mouse click (or query) on a chart display.

That is, new source data and critical corrections are compiled into NOAAs ENC production database first and the compiled portrayal of that data is subsequently applied to the corresponding paper charts and their associated digital raster products.

This sequential compilation process ensures the consistent equivalent portrayal of data between ENCs and paper nautical charts.

These digital images, identical to NOAA paper nautical charts, include the NOAA raster navigational chart (NOAA RNC) also known as BSB format, full-size and booklet charts released as PDF files, and RNC tile service data.

This enables NOAA to provide the public with updated information as early as possible in ENCs.

Strict synchronization of ENC and raster products would require holding back the release of updated ENCs to enable the paper charts to catch up.

Releasing ENCs first is in the best interest of safe navigation.

Chief among these are hydrographic surveys used to update water depth values and the positions of rocks, wrecks, and other hazards; and topographic surveys used to update shorelines and some landmarks.

The application of these surveys usually constitutes a major update for ENCs and paper charts.

After compilation, this data is released to the public at the next weekly update of ENC products, which usually occurs on Thursdays.

This same data may not appear on some paper charts for up to a month or longer, and in some cases, it may not be published until the next new edition of the chart, which could be several months or even a few years away.

NOAA is transitioning its paper nautical charts to show only the channel project design depths in many ports.

New minimum channel depths are provided as often as monthly for some channels.

Read more about this on the NOAA announces change in channel depths on raster nautical chart products, blog post.

However, unlike the diagrams on a paper chart, the quality of the surveys indicated by a number of stars may be toggled on and off over the ENC data itself.

This is easier than trying to match an area on a chart to the charts source diagram and then look up a quality category keyed to a letter shown on the diagram.

They are also available from a number of value added resellers who offer services such as increased security through encryption and managed chart updates.

This more detailed data will only be available in the ENC format.

There are no plans to create new, larger scale paper charts.

Loading ENC revision files automatically apply all the latest ENC updates.

This can reduce clutter and make other important features easier to see that are more relevant for a particular activity in which a ship is engaged.

The minimum scale attribute that is encoded for many ENC features also enables systems to suppress the display of certain features when a chart is zoomed out to a point where a features display would clutter the chart.

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