Who lets the mariner know when a chart needs correction, and how?
Hydrographic organisations that produce charts are also responsible for their correction. Probably the best known one is the Hydrographic Department in the UK, which publishes British Admiralty (BA) Charts. We will take this as an example in these articles.
The systemic way in which charts are corrected are as follows:
1. The Admiralty receives information about changes to chart information from hydrographic departments across the world
2. It collects this information, referencing it to which charts need to be corrected (there are thousands of charts that cover the globe; each has a unique identification number)
3. It sends weekly ‘Notices to Mariners’ to owners of vessels that carry BA charts; the owners then pass these on to the vessels at their next port. There are 52 such notices annually. These notices are also downloadable or can be sent electronically otherwise, and are a compilation of all corrections for the week; a typical booklet of these notices will be about fifteen sheets thick.
4. These notices contain full details of which charts (and publications) are affected by the corrections carried in the notice. Further, these notices detail what corrections need to be made on board. The Notices are usually accompanied by tracings for each chart affected; these tracings are overlaid temporarily on each chart and the correction ‘traced’ onto the chart for easy, accuracy and speedy chart correction.
5. These notices are also sent to suppliers of BA charts worldwide, who may have BA charts in stock but may not have sold them yet.
6. Second Officers on these ships (and BA agent employees ashore in the second case above) are responsible for chart correction. They receive the notices and cross reference them with which charts they have on board (or in the ‘ship’). They then correct them. Note that this means that whenever a chart is purchased, it is always correct to the nearest notice for large corrections only (more later)
7. At sea, the charts are corrected and a log is maintained indicating which chart has been corrected to which notice. This becomes a ready reference whenever required.
8. This is a continuous process, and a critical one. The safety of the crew, cargo and the ship depends on a systematic and accurate means of chart correction- and indeed, correction of all publications, information on which is also available in the same Notices to Mariners.