Nautical charts should be corrected every week and replaced whenever a new edition is published. Hydrographic offices issue Notices to Mariners weekly, and a chart is only current if every notice since its edition date has been applied. Electronic charts follow the same principle on a faster or slower cycle depending on the service: official ENCs update weekly or more often, while recreational chartplotter libraries are typically refreshed a few times a year.
How Often Are Nautical Charts Updated?
The answer depends on the chart type. The table below shows the normal update cycle for each.
| Chart type | How it is updated | Typical frequency |
|---|---|---|
| ADMIRALTY paper charts | Hand corrections from ADMIRALTY Notices to Mariners | Weekly, plus new editions as published |
| US (NOAA) paper charts | Printed on demand from current NOAA ENC data, then kept current from US notices | Current at printing, then weekly notices |
| Official ENCs (for example ADMIRALTY AVCS) | Digital update files loaded into ECDIS | Weekly |
| NOAA ENCs | Updated in NOAA's ENC database | Weekdays |
| C-Map chartplotter libraries | Updated library loaded to the plotter or card | About twice a year |
Two terms are worth separating before going further:
- A correction changes part of an existing chart, such as a moved buoy, a new wreck, or a changed light.
- A new edition replaces the chart entirely and cancels the old one.
Weekly Notices to Mariners vs New Editions
Weekly Notices to Mariners keep a chart current between editions. ADMIRALTY notices are issued weekly by the UK Hydrographic Office and are available as free weekly downloads. US charts are corrected from the weekly US Notice to Mariners published by the National Geospatial-Intelligence Agency, supplemented by US Coast Guard Local Notices to Mariners for coastal and inland waters. The ANS guide to Notices to Mariners walks through how each notice is applied.
New editions arrive on no fixed schedule. A busy port approach may see a new edition within a year or two, while an ocean chart can go many years between editions. Each new ADMIRALTY edition is announced in the weekly notices, and from that week the old edition is cancelled. Notices only ever apply to the edition currently in force.
US paper charts changed fundamentally in 2024. NOAA cancelled the last of its 1,007 traditional paper charts in December 2024 and now maintains only its ENC database. Print-on-demand paper charts that carry the familiar NOAA chart numbers are now generated from that ENC data at the moment they are ordered. A freshly printed NOAA chart is therefore current on the day it is printed, and every notice issued after that date still has to be applied.
How to Tell If a Nautical Chart Is Out of Date
A chart can be checked in a few minutes. The steps differ slightly by chart type.
ADMIRALTY paper charts
- Read the edition date in the bottom margin of the chart.
- Compare it with the latest edition date listed in the Cumulative List of ADMIRALTY Notices to Mariners (NP234) or announced in the weekly notices since then. An older date means the chart is cancelled.
- Check the last notice recorded in the bottom left-hand corner of the chart against the latest weekly notice. Any gap means corrections are missing.
- Confirm that temporary and preliminary notices plotted in pencil are still in force.
NOAA print-on-demand charts
- Note the date the chart was printed.
- Check US notices issued since that date, or use NOAA's Navigation Updates tool to see whether the underlying ENC data has changed.
- For charts printed long ago, ordering a fresh print is often simpler than applying months of corrections.
Electronic charts and chartplotters
- On an ECDIS, check the chart status report to confirm the latest weekly update has been applied, and permits are valid.
- On a chartplotter, check the chart library's release date in the system menu and compare it with the latest available release.
Signs that a chart needs attention:
- The edition date is older than the latest listed edition
- No correction has been recorded for several weeks on a chart that covers busy waters
- Buoys, lights, or marina details on the chart do not match what is visible on the water
Keeping Digital Charts Current Automatically
Digital charts remove the hand corrections, but they do not update themselves without a subscription and a way to load the data.
- Official ENCs for ECDIS, such as ADMIRALTY AVCS, are corrected through weekly update files. Services like SPICA e-Navigator and SPICA Gateway can deliver those updates to the ECDIS automatically.
- Recreational chartplotter libraries are replaced as a whole. C-Map libraries are refreshed about twice a year to coincide with boating seasons, and each release folds in the hydrographic office notices issued since the last one. Update products for owners of existing cards are listed in the C-Map MAX chart updates and C-Map 4D chart updates collections.
- MapMedia vector charts used in PC-based navigation software are updated through dedicated update products, listed in the MapMedia digital chart updates collection.
A chartplotter library that is several seasons old has missed every correction issued since its release. For coastal cruising, keeping the library within the latest release cycle closes most of that gap. The ANS overview of digital charts covers the services available for each type of system.
Browse the Nautical Chart Catalogue
Whether a passage relies on a paper folio, an ECDIS, or a chartplotter, the answer to "is this chart current?" should be yes before the lines come off. ANS supplies ADMIRALTY charts corrected to date, NOAA print-on-demand charts, and digital chart updates.
Browse the nautical chart catalogue at amnautical.com, or contact ANS at +1 (954) 522-3321 or sales@amnautical.com to confirm the current edition of any chart.
Frequently Asked Questions
How often should nautical charts be updated?
Every week. Notices to Mariners are issued weekly, and each one that affects a chart should be applied. A chart should also be replaced as soon as a new edition is published.
How do I know if my nautical chart is current?
Compare the chart's edition date with the latest edition listed by the hydrographic office, then check that every Notice to Mariners issued since that edition has been applied and recorded on the chart.
Can I still use an older-edition paper chart?
Not as a navigational chart. Once a new edition is published, the old one is cancelled, no further corrections are issued for it, and on commercial vessels it no longer meets SOLAS carriage requirements. Older editions are useful only as reference.
Do digital charts update automatically?
Only with an active subscription and a way to deliver the data. Official ENC services issue weekly updates that can be delivered automatically, while chartplotter libraries such as C-Map are replaced with periodic releases.
Where do I find the latest Notices to Mariners?
ADMIRALTY Notices to Mariners are free to download weekly from the UK Hydrographic Office. US notices are published weekly by the NGA, with Local Notices to Mariners issued by each US Coast Guard district.
Are NOAA paper charts still available?
Yes, in a new form. NOAA ended its traditional paper charts in December 2024, and print-on-demand charts carrying NOAA chart numbers are now produced from current NOAA ENC data when ordered.
