Unit 1 Nautical Publications Lesson 2 Nautical Charts 海图

The main text of the upБайду номын сангаасate starts with one of the following commands, usually in the order shown: INSERT is used for the insertion of all new data or, together with the DELETE command (see below), when a feature has moved position sufficiently that the MOVE command (see below) is not appropriate. For example: Delete feature and Insert in a different position. Note: The exact text to be written on a chart by insertion will appear in Italics in the printed notice.
The amount of detail shown on a chart varies with its scale. On a large scale chart, for example, full details of all lights and fog signals are shown, but on smaller scales the order of reduction of information is Elevation, Period, Range, until on an ocean chart of the area only lights with a range of 15 miles or more will normally be inserted, and then only their light–state and magenta flare. On the other hand, radio beacons are omitted from large scale charts where their use would be inappropriate, and, unless they are long range beacons, from ocean charts.
Crafts Series available at even smaller scales. Mariners should always use the largest scale nautical chart appropriate to their needs. In particularly busy seaways such as the English Channel, Gulf of Suez and the Malacca and Singapore Straits, the standard nautical charts are supplemented by mariners’ routeing guides which provide advice on route planning in these complex areas.
Text A Use of the Chart Mariner should always use the largest scale chart appropriate for his purpose. In closing the land or dangerous banks, regard must always be had to the scale of the chart used. A small error in laying down a position may mean only a few metres on a large scale chart, whereas on a small scale the same amount of displacement on the paper may mean several cables. For the same reason bearings to near objects should be used in preference to objects farther off, although the latter may be more prominent, as a small error in bearing or in laying it down on the chart has a greater effect in misplacing the position the longer the line to be drawn.
L2 Nautical Charts
Contents
Introductions to Admiralty Charts and Electronic Charts; Use of Chart, in particular ,Usual Command for updating charts Symbols and Abbreviations used on Admiralty Charts.
MOVE is used for features whose characteristics or descriptions remain unchanged, but they are to be moved small distances, for example: Move starboard–hand conical buoy from 56°00′.62°N, 4°46′.47W to 56°00′.93N, 4°46′.85W. DELETE is used when features are to be removed from the chart or, together with the INSERT command (see above), when features are moved a significant distance such that the MOVE command is inappropriate. Full details of chart updating methods can be found in How to Keep Your Admiralty Charts Up–to–Date.
Electronic charts Electronic charts are manufactured and distributed by both government Hydrographic Offices and by private companies. Only officially produced electronic charts (i.e. those manufactured by, or on the authority of, government Hydrographic Offices), may be used for primary, paperless navigation, provided that they are installed on ECDIS equipment which meets IMO performance standards. Electronic charts are of two distinct types, vector and raster.
Charts include: depths (chart datum), coastline, buoyage, land and underwater contour lines, seabed composition (for anchoring), hazards, tidal information, prominent land features, traffic separation schemes, RF direction finding information, lights, and in short anything which could assist navigation.
Admiralty charts Admiralty charts are nautical charts issued by the United Kingdom Hydrographic Office and subject to Crown Copyright. Over 3,300 charts are available and cover virtually the entire world in various levels of detail depending on the density of traffic and hazards. Large-scale charts often cover approaches and entrances to harbours, medium-scale charts cover heavily used coastal areas, and small-scale charts are for navigation in more open areas. There is also a Small
Text B Symbols and Abbreviations Used on Admiralty Chart Chart 5011 — Symbols and Abbreviations used on Admiralty Paper Charts is published as an A4– size book, and can be conveniently kept with this book. The numbering convention follows that of International Chart 1 (INT1). It is treated as a chart, and is updated by Admiralty Notices to Mariners. The contents of Chart 5011 include General, Topography, Hydrography, Navigational Aids Services, and Alphabetic Indexes. Some symbols and abbreviations frequently used on Admiralty Paper Charts are selected to assist learners to familiarize themselves with Admiralty Charts.