The USCG LNM is published weekly by each of 9 individual Coast Guard Districts.

In order for the mariner to transit safely, it is imperative that these changes be reflected on nautical charts as soon as practicable. Lawrence Seaway, the Canadian Coast Guard Notice to Mariners.

navigation chart updating kit-30

POD charts will show the dates of the latest LNM and NMs applied to the chart.

Once a mariner owns a POD chart, that chart must be updated from thereon manually.

BSB format, a compressed raster format, and the digital differences between the updated chart and the base edition are isolated into an update or patch file.

NOAA posts these updated files on the Internet where they are available for free download.

By clicking on the link below to proceed to the NOAA Chart Update Web Site Data Search, the user acknowledges that they have read and agree to the above terms and conditions.

Clicking on the button below signifies acknowledgement of having read the above statement and wish to proceed to the Chart Updates Data Search section.

If the mariner chooses to purchase a POD chart, all updates that have been published in the one year between the new edition date and the purchase date have already been applied.

NOAA cartographers maintain a master electronic copy of every new chart edition.

The NGA NM, for the most part, contains the same information published in the USCG LNM.