How to Apply Chart Corrections

The leisure boater might be forgiven for assuming that the appropriate folio of charts and an almanac might be all that is required in order to navigate safely and responsibly. However, things change. You wouldn't rely on an out-of-date almanac and neither should you rely on an out-of-date chart. However, replacing charts is an expensive process and, with a little effort, it can be largely avoided.

The key is to keep your chart folio up to date. To do this is simple enough and will require only that you possess the following;

Chart 5011 Admiralty Symbols and Abbreviations
A fine-nibbed Magenta pen
Paper Chart Maintenance Record NP133A
Regular visits to the Notice to Mariners Updates 

A Notice to Mariners includes Textual Notices to Mariners (NMs), blocks, tracings and notes. Textual NMs are your primary source. Tracings and blocks are a graphic representation of the textual NM.

To update a nautical chart follow this procedure;

On receipt of the Notice to Mariners, check to see which of your charts are affected. Then, using a pencil, mark in the relevant chart references in the NP133A record. The entry should include the year followed by a hyphen and the NM ref number.

Update your paper chart as follows:

  1. Check the NM and any textual updates, tracings, blocks and notes.  Tracings are available in A4 or A5 and each one displays the Chart number, the last chart update and shows a 3 x 3 grid with one grid shaded. That shaded grid locates the position on the chart upon which the amendments are to be made.
  2. Before you apply an amendment, check that the chart you are working on is up-to-date. To do this, check the chart’s last NM number in the bottom left corner of the chart.Then, using the magenta pen, making reference to Chart 5011, make the update and write the NM number in the bottom left hand corner in magenta pen. Write the year (i.e. 2018) first and underline it then insert a hyphen and then insert the NM ref number. This ensures that you are always aware of what has been updated and when.
  3. Finally, using a pencil (preferably 2B) cross through the Notice to Mariners ref number in the NP133A so as to illustrate that this update has been applied.

Of course, many of the Notice to Mariners will not be relevant to your sailing area and so a quick cursory look should satisfy you of any changes without any need to update charts at all. However, when planning a coastal or offshore passage, updating charts should be one of your tasks before leaving port.

Click here to view the latest Notice to Mariners.