Editing Navigator (section)

== Nautical charts ==
{{Further|Nautical charts}}
[[Image:NOAA chart 25664 1976.png|right|thumb|A 1976 United States [[National Oceanic and Atmospheric Administration|NOAA]] chart of part of [[Puerto Rico]]]]
A naval ship's navigator is responsible for buying and maintaining its nautical charts.  A nautical chart, or simply "chart", is a graphic representation of a maritime or flight region and adjacent coastal regions. Depending on the scale of the chart, it may show depths of water and heights of land, natural features of the seabed, details of the coastline, navigational hazards, locations of natural and man-made aids to [[navigation]], information on tides and [[Ocean current|current]]s, local details of the [[Earth's magnetic field]], restricted flying areas, and man-made structures such as [[harbor]]s, buildings and [[bridge]]s. Nautical charts are essential tools for marine navigation; many countries require vessels, especially commercial ships, to carry them. Nautical charting may take the form of charts printed on paper or computerised [[electronic navigational chart]]s.

The nature of a waterway depicted by a chart changes regularly, and a mariner navigating on an old or uncorrected chart is courting disaster. Every producer of navigational charts also provides a system to inform mariners and aviators of changes that affect the chart.  In the United States, chart corrections and notifications of new editions are provided by various governmental agencies by way of Notices to Airmen (NOTAMs),  [[Notice to Mariners]], [[Local Notice to Mariners]], [[Summary of Corrections]], and Broadcast Notice to Mariners.  Radio broadcasts give advance notice of urgent corrections.

A convenient way to keep track of corrections is with a "chart and publication correction record card" system.  Using this system, the navigator does not immediately update every chart in the portfolio when a new Notice to Mariners arrives, instead creating a card for every chart and noting the correction on this card. When the time comes to use the chart, the navigator pulls the chart and chart's card, and makes the indicated corrections on the chart. This system ensures that every chart is properly corrected prior to use.  British merchant vessels receive weekly Notices to Mariners issued by the [[British Admiralty|Admiralty]].  When corrections are received all charts are corrected in the ship's folio and recorded in [[NP133A]] (Admiralty Chart Correction Log and Folio Index).  This system ensures that ''all'' charts are corrected and up to date.  In a deep-sea vessel with a folio of over three thousand charts this can be a laborious and time-consuming task for the navigator.

Various and diverse methods exist for the correction of electronic navigational charts.