NOAA Electronic Navigational Charts

What you can build

• Keep a vessel inside the charted channel

  Overlay AIS positions on the ENC cell for the harbor. When a track leaves the charted fairway or crosses a depth contour shallower than the vessel's draft, the operator proposes a deviation alert for the dispatcher.

  With Route Deviation, Field Dispatch

• Annotate operations when a chart you rely on changes

  Fetch OneDay_ENCs.zip each weekday evening. When a cell covering your berths appears, the operator proposes a change note on the dock schedule with the cell name and date.

  With Change Annotation, Dock Schedule

• Plan a workboat dispatch against charted hazards

  Before assigning a workboat, the operator reads aids to navigation and obstructions from the cell and proposes a route with the charted features it avoided.

  With Field Dispatch, Route Resequence

Requirements

• An S-57 reader or a GIS that opens ENC cells, or the exports from ENC Direct to GIS
• A cell inventory for your waters taken from ENCProdCat_19115.xml or the district bundle
• A weekday fetch of the OneDay or TwoDays bundle to pick up update cells
• Display of the NOAA ENC user agreement and a reference to charts.noaa.gov if you copy cells to your own server

Authentication

None. Downloads from charts.noaa.gov are open, subject to the NOAA ENC user agreement shown on the download site.

Limits

• Copies redistributed from other servers do not meet federal chart carriage rules unless they come from NOAA or a distributor NOAA lists
• Coast Survey describes weekly updates as best efforts with no guaranteed timing
• Per the user agreement, some depths rest on surveys made before 1940 and some shoreline data is more than 20 years old
• ENC Direct to GIS does not meet USCG chart carriage requirements for commercial vessels

Questions and answers

How often do ENC cells change?

Coast Survey says new ENC update cells are uploaded every weekday evening, covering critical changes such as aids to navigation and routine additions of newly compiled data. The user agreement describes weekly updates as best efforts with no guaranteed timing.

Can I redistribute the cells?

Yes, with conditions. The NOAA ENC user agreement says redistributed cells do not count as NOAA ENCs for federal chart carriage unless they come through a distributor NOAA lists, and that copies placed on another server must display the agreement and reference the original site.

Is there a way to get ENC features as GIS layers?

Yes. ENC Direct to GIS at encdirect.noaa.gov lets you display, query, and download all base editions of NOAA ENC data in GIS and CAD formats, organized by S-57 object class and updated weekly. It is not for chart carriage.