![]() ![]() Various and diverse methods exist for the correction of electronic navigational charts. The information in the Notice to Mariners is formatted to simplify the correction of paper charts and navigational publications. This electronic publication is published on a monthly basis and can be downloaded from the Notices to Mariners (NOTMAR) Web site. The Canadian Coast Guard produces the Notice to Mariners publication which informs mariners of important navigational safety matters affecting Canadian Waters. Tracings to assist corrections are provided at the same time. These systems provide only vessel relevant corrections via e-mail or web downloads, reducing the time needed to sort out corrections for each chart. Various Digital Notices to Mariners systems are available on the market such as Digitrace, Voyager, or ChartCo, to correct British Admiralty charts as well as NOAA charts. ![]() A prudent mariner should obtain a new chart if he has not kept track of corrections and his chart is more than several months old. This system ensures that every chart is properly corrected prior to use. When the time comes to use the chart, he pulls the chart and chart's card, and makes the indicated corrections on the chart. 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. To give notice to mariners, radio broadcasts provide advance notice of urgent corrections.Ī good way to keep track of corrections is with a Chart and Publication Correction Record Card system. In the U.S., NOAA also has a printing partner who prints the "POD" (print on demand) NOAA charts, and they contain the very latest corrections and notifications at the time of printing. In the United States, chart corrections and notifications of new editions are provided by various governmental agencies by way of Notice to Mariners, Local Notice to Mariners, Summary of Corrections, and Broadcast Notice to Mariners. Every producer of nautical charts also provides a system to inform mariners of changes that affect the chart. Therefore, old or uncorrected charts should never be used for navigation. ![]() The nature of a waterway depicted by a chart may change, and artificial aids to navigation may be altered at short notice. There are also commercially published charts, some of which may carry additional information of particular interest, e.g. ![]() Coordinated by the International Hydrographic Organization, the international chart series is a worldwide system of charts ("INT" chart series), which is being developed with the goal of unifying as many chart systems as possible. Individual hydrographic offices produce national chart series and international chart series. Many hydrographic offices provide regular, sometimes weekly, manual updates of their charts through their sales agents. These charts are considered "official" in contrast to those made by commercial publishers. Nautical charts are issued by power of the national hydrographic offices in many countries. This ensures that difficult to find projections, such as masts, do not present a danger to vessels navigating over the obstruction. When measuring the safe depth of water over an entire obstruction, such as a shipwreck, the minimum depth is checked by sweeping the area with a length of horizontal wire. In modern times, echo sounding is used for measuring the seabed in the open sea. Depths are measured in a variety of ways. As surveying is laborious and time-consuming, hydrographic data for many areas of sea may be dated and are sometimes unreliable. Nautical charts are based on hydrographic surveys and bathymetric surveys. With each daily download, critical data such as Local Notices to Mariners are added to the on-demand chart files so that these charts are up to date at the time of printing. Recent technologies have made available paper charts which are printed "on demand" with cartographic data that has been downloaded to the commercial printing company as recently as the night before printing. Nautical charting may take the form of charts printed on paper (raster navigational charts) or computerized electronic navigational charts. Nautical charts are essential tools for marine navigation many countries require vessels, especially commercial ships, to carry them. Depending on the scale of the chart, it may show depths of water ( bathymetry) and heights of land ( topography), natural features of the seabed, details of the coastline, navigational hazards, locations of natural and human-made aids to navigation, information on tides and currents, local details of the Earth's magnetic field, and human-made structures such as harbours, buildings, and bridges. A nautical chart of the Warnemünde harbor shown on OpenSeaMapĪ nautical chart or hydrographic chart is a graphic representation of a sea region or water body and adjacent coasts or banks. ![]()
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