Electronic charts (NOAA ENC) and the end of NOAA paper charts
Navigation
Charts on a plotter, tablet or computer. The official US government charts are now NOAA's electronic navigational charts (ENCs); NOAA finished cancelling its traditional paper and raster charts in December 2024. You can still print paper charts from ENC data with NOAA's free Custom Chart tool.
How it works
An ENC is a vector chart: a database of charted features with exact positions and details, so a plotter can redraw it at any scale and warn you about shallow water. NOAA ENCs are free from NOAA's website, and NOAA posts update files every weekday evening. Many plotters use their maker's own chart cards instead, updated on the maker's schedule. Raster charts (RNC or BSB files) were scanned images of the paper charts; NOAA has cancelled them.
Using it
- Update your charts before the season and before a trip. NOAA's Navigation Updates website shows where charts have changed, including critical changes from the Local Notice to Mariners.
- Set a safety depth or safety contour for your draft on the plotter so shallow water stands out; ENC data lets plotters warn when you head into shallow water.
- Expect some depth contours at odd-looking foot values: NOAA's new, more detailed ENC cells use standard contours in whole meters.
- Carry a backup: a second device with charts, or paper printed from NOAA Custom Chart, which uses the same ENC data with traditional paper-chart symbols. NOAA itself says paper is still useful for planning and as a backup.
- Make sure positions you plot are on the same datum as the chart. NOAA charts use NAD 83/WGS 84, and NOAA warns the shift from older datums such as NAD 27 is significant.
- For inland rivers, the US Army Corps of Engineers publishes Inland ENCs.
- Old editions and training charts on NOAA's Historical Map & Chart Collection are for reference or framing only, not for navigation.
Looking after it
- Load ENC updates or updated chart cards regularly; most systems apply ENC update files automatically when loaded.
- Check the edition or update date of the charts in use from the plotter's chart information screen.
- Keep the plotter's software up to date; the GPS.gov program advises keeping GPS device software current and reporting faults to the maker.
Troubleshooting
Chart shows blank areas or little detail
- Zoom in; some detail appears only at larger scales.
- Check the chart card is inserted, or the right ENC cells are loaded for that area.
- Check coverage on NOAA's Chart Locator and download any missing cells.
Boat symbol is offset from what you see, or a plotted position lands in the wrong place
- Check the plotter and any position you're plotting use the chart's datum (WGS 84/NAD 83); older positions and charts may be on NAD 27.
- Check the GPS has a good fix.
- Remember charts are only as good as their survey data; slow down and use eyes, depth sounder and radar in doubtful spots.
New buoys or changes missing from your chart
- Load the latest ENC updates or chart card update.
- Check NOAA's Navigation Updates site and the Coast Guard Local Notice to Mariners for your area.
Buying a boat that has one
- Check the date of the plotter's chart cards and whether the maker still sells updates for that plotter.
- A stack of NOAA paper charts aboard is now historical: NOAA no longer corrects or reissues them. Print current charts from NOAA Custom Chart instead.
- Older PC or tablet navigation software that relies on NOAA raster (BSB) charts won't get new NOAA editions; check whether it can load NOAA ENC files.
- Ask for the plotter's software version and whether the maker still supports it.
Sources (6)
nauticalcharts.noaa.gov · nauticalcharts.noaa.gov · nauticalcharts.noaa.gov · nauticalcharts.noaa.gov · nauticalcharts.noaa.gov · gps.gov
General guidance for recreational boaters, researched from the sources listed and written in our own words. Your equipment manuals, local knowledge, the Navigation Rules and a qualified instructor come first.