Chart Correction and Notices to Mariners

Why charts must be corrected

In short: Read compulsory nautical publications and chart projections, scales and datums first. A chart is only legal if it is the latest edition and corrected. The UK Hydrographic Office (UKHO, trading as ADMIRALTY) keeps its charts and books up to date through Notices to Mariners (NMs).

The rule

• SOLAS V/27: charts and publications for the voyage must be adequate and up to date (MGN 610 (M+F), para 34.1).
• They must be the latest obtainable edition, kept up to date from the latest Notices to Mariners and radio navigational warnings (MGN 610 (M+F) Annex B, 1.2.2).
• The carriage rule itself is SOLAS V/19.2.1.4–2.1.5: charts (or ECDIS) for the voyage, with a back-up if electronic. See bridge equipment carriage rules.
• The MCA accepts the weekly NMs in paper or digital form for SOLAS V/19.2.1.4 (ADMIRALTY Maritime Safety Information).
• On the bridge: the Master or a PSC inspector picks a chart from the folio and asks “Is this up to date?” You must be able to prove it.

The three NM products at a glance

• Order of use: Cumulative → Weekly → chart (for publications: Annual Part 2 → Weekly).
• Free to download from the ADMIRALTY Maritime Safety Information website, or as printed weekly booklets from an ADMIRALTY distributor.

The Weekly Notices to Mariners and T&Ps

In short: The Weekly NM is the working document: 8 sections, published every week by ADMIRALTY. Corrections are either permanent or T&Ps (Temporary and Preliminary).

The 8 sections

Mnemonic: “Exploration Charts Navigate Sailors, 2 Lists of Miscellaneous E-Pubs”.

1. Explanatory notes and publications list.
2. Charts: updates (corrections) to ADMIRALTY Standard Nautical Charts, T&Ps at the end.
3. Navigational warnings: reprints of radio navigational warnings (NAVAREA I).
4. Sailing Directions: amendments.
5. Lists of Lights and Fog Signals: amendments.
6. Lists of Radio Signals: amendments.
7. Miscellaneous ADMIRALTY publications: amendments.
8. E-Pubs: digital products and services.

• Know the sections well enough to say where to look: a moved buoy is in II, a new VTS channel in VI, a changed light character in V (and in II for the chart). Light characters themselves: light descriptions and ranges.

Section IA and Section IB

• Section IA: the list of T&Ps in force and those cancelled. It comes out every 4 weeks (often called “monthly”). Always check the latest one.
• Section IB (quarterly, end of March, June, September and December): the current editions of ADMIRALTY publications.

T&Ps: Temporary and Preliminary notices

• Temporary (T): a change that will not last, e.g. a light out of service or a buoy moved during dredging.
• Preliminary (P): advance warning of a change that is coming, e.g. harbour works or a new edition of the chart.
• Marked (T) or (P) after the notice number, at the end of Section II.
• How they differ from a normal correction: a permanent correction goes on in magenta ink; a T&P goes on in pencil, so it can be rubbed out when it is cancelled.
• Where to find them: Annual Summary Part 1 (T&Ps in force on 1 January), then Section II of every weekly since, checked against the latest Section IA.
• ❌ T&Ps are not in the Cumulative List.

The Cumulative List and the Annual Summary

In short: The Cumulative List tells you whether a chart is the latest edition and which permanent corrections it needs. The Annual Summary holds the notices that stay valid all year, the T&Ps in force and the Sailing Directions corrections.

The Cumulative List (NP234)

• Published twice a year: NP234A in January and NP234B in July (UKHO). You will also hear “January and June” for the two issues; the UKHO says July.
• Contents:
  • Chart numbers in numerical order.
  • The latest edition date of each chart.
  • The permanent NMs for each chart over the last 2 years (January issue) or 2½ years (July issue). The week of each NM is shown in brackets.
  • The edition status of other ADMIRALTY publications.
• Use: it catches any correction missed in the weekly routine and gives an audit trail for each chart.
• Available online free from the ADMIRALTY Maritime Safety Information website.

The Annual Summary (NP247), Parts 1 and 2

• Published every January, in force from 1 January.
• Part 1 (NP247(1)):
  • Annual NMs of a general, repeated nature: ADMIRALTY chart agents, areas of war or conflict, naval exercise areas, claims of national jurisdiction (territorial sea, contiguous zone, EEZ), wrecks and war graves.
  • Reprints of the T&Ps still in force.
  • Lasting information is often moved into other books, such as The Mariner’s Handbook (NP100).
• Part 2 (NP247(2)): a full reprint of the corrections to Sailing Directions still in force from the previous year (current editions and amendments).

Correcting a paper chart step by step

In short: Prove the chart is current with the Cumulative List and the bottom left-hand corner (BLC), find what is missing in the Weekly NMs, correct in magenta, then record it in the BLC and in NP133A.

Is this chart up to date?

1. Open the Cumulative List and find the chart number.
2. Check the chart is the latest edition (compare the edition date).
3. Note the permanent NMs listed for it (week numbers in brackets).
4. Look at the BLC of the chart: which corrections are already done?
5. Check every Weekly NM published since the Cumulative List (under 6 months) for permanent corrections and T&Ps. Start with the most recent weekly and work backwards: it saves time.
6. Check valid T&Ps against the latest Section IA.

Applying the correction

1. When a new weekly arrives, find which charts in your folio need a correction (the folio may carry a QR code or index to help).
2. Take each chart one at a time.
3. If an earlier correction was missed, apply that one first.
4. Apply permanent corrections in magenta ink; T&Ps in pencil.
5. Write the NM serial number in ink in the BLC.
6. Only when the chart is finished, record it in the chart correction log: NP133A, the Paper Chart Maintenance Record.
7. Keep the log up to date: it should match the BLC, so it works as a double check.

• Tools that help: NM tracings (they show where each correction goes), full-colour NM blocks (patches you paste on for bigger changes) and NM Websearch, which finds NMs by chart number.
• Full guidance: NP294, How to keep your ADMIRALTY Products Up-to-Date.

Correcting the publications

• Start from the Annual Summary Part 2, then every weekly NM since.
• Sections IV to VII of the weekly: Sailing Directions, List of Lights, ALRS, miscellaneous publications.
• Same idea as charts: apply in order, record what you did.

Electronic charts and maritime safety information

In short: ENCs are corrected by digital updates, not by hand. Apply them from an approved source, on both ECDIS units, and keep a record. Between NMs, NAVTEX and radio warnings keep you up to date at sea.

Updating ENCs on ECDIS

• Download updates only from approved sources (e.g. the ADMIRALTY Vector Chart Service).
• Use a bridge computer free from malware; move the files with a clean, encrypted USB key.
• ENC updates are cumulative: each one includes the earlier ones.
• Updates available in port: apply them before passage planning and before sailing. Updates received at sea: apply them as soon as possible (MGN 610 (M+F) Annex C, 1.2.2).
• Apply to both primary and secondary systems (Annex C, 1.2.3) and record when each update was received and applied (Annex C, 1.2.4).
• The back-up ECDIS must also be loaded with updated official charts and the voyage plan (MGN 610 Annex G, 1.2.3).
• Check it is up to date: the ECDIS update status against the latest weekly, and the software to the current IHO standard (S-52) (Annex G, 1.3.3–1.3.4). For the ECDIS display itself see radar maps and ECDIS overlay.

MSI: NAVTEX and radio warnings

• Charts must also be corrected from radio navigational warnings (MGN 610 Annex B, 1.2.2). A weekly NM can be a week old; a NAVTEX warning is today’s news.
• Before the voyage: read the warnings in force for the area and plot them on the chart (pencil). During the voyage: monitor NAVTEX and VHF/MF broadcasts on every watch.
• In the UK, HM Coastguard broadcasts maritime safety information on VHF, MF and NAVTEX (MGN 610 Annex A, 10.2). Where and when: weather forecasts and information at sea.
• Section III of the weekly NM reprints the NAVAREA I warnings.
• Found a new danger or a light not working? Report it to the UKHO at once (MGN 610 Annex A, 7.4).