Nautical chart
A nautical map is a map that shows the areas for shipping, the sea lanes and coasts , shallows , sea marks , fairways etc. of a certain sea area (e.g. North Sea).
The scales of nautical charts range from about 1: 25,000 to 1: 100,000 (for large-scale coastal maps ) to 1:10 million (small-scale ocean maps ), which are also called overseas sailors .
history
Map content
A large-scale nautical chart contains, in addition to the indication of the scale and the year of publication with the status of the correction, etc. a.
- the coastline,
- Contour lines (0 m, 2 m, 5 m, 10 m, 20 m and 50 m are common) and individual depths based on the chart zero ,
- the navigation marks as standardized symbols,
- in the case of beacons, details of the sectors in which the beacon lights up in which colors and with which identifiers,
- Wrecks and other underwater obstacles such as B. large stones, pipelines or submarine cables ,
- Information about dangerous watercraft such as B. HSC (high speed watercraft),
- Warnings about unreliable depth information, anomalies in the earth's magnetic field, dangerous currents, etc.,
- Traffic separation areas and waterways ,
- military and other restricted areas ,
- the main towns, routes and heights near the coast,
- a graticule of longitude and latitude ,
- the magnetic declination ( magnetic declination , difference between true north and magnetic north) and its annual change.
Land areas (usually areas above mean flood ) are shown with a yellowish area tone, the shallow water area in different shades of blue, dry areas (areas with an altitude between chart zero and MHW) z. B. Watt colored green. The deep water areas have a white background. Nautical symbols, symbols, abbreviations and terms in nautical charts are listed in so-called Map 1 ( INT 1 ).
Map projection
A nautical chart is usually a Mercator chart, i.e. a true-angle projection of the earth's surface onto a circular cylinder. In this projection, Arctic and Antarctic areas are shown greatly enlarged; the longitude and latitude appear as straight lines and intersect at right angles. One minute of latitude corresponds to 1 nautical mile (approx. 1.852 km).
Official nautical charts
The official nautical charts in Germany are issued by the Federal Maritime and Hydrographic Agency (BSH). This used to be done by the German Hydrographic Institute (DHI) and the Sea Hydrographic Service of the GDR (SHD). The German nautical chart work has been limited mainly to German waters since 2014. There is also a small-scale map of the North Sea and Baltic Sea as well as individual maps of the Antarctic .
Free nautical chart
As part of OpenStreetMap , various free nautical map projects such as OpenSeaMap or FreieTonne have developed in recent years . Here everyone can contribute their knowledge of sea areas , ports and marinas as geographical map information and as text data in the sense of a port manual . Based on the technical infrastructure of OpenStreetMap, data on the world's oceans and inland waterways ( beacons , fairway buoys , port information and many other nautical geographic information) are recorded and displayed. There are first approaches to visualize the data on laptop computers and GPS devices. However, it should be noted that these types of nautical charts are not suitable for navigation, as neither topicality nor correctness can be guaranteed.
OpenSeaMap offers a worldwide nautical map as an app for iPad, iPhone and iPod, as well as a vector map for all of Europe for Garmin ship plotters.
Use of a paper map
The use of a printed chart requires in shipping a card cutlery , so dividers , price triangles and pencil . Positions on the nautical chart are geometrically constructed according to various methods by making two, or better three, lines intersect. Theoretically, three lines should also intersect at the same point, but instead often form a small error triangle, the center of which can be assumed to be the location at the time the location was determined. Visually determined positions are surrounded by a small circle and those determined by radio navigation are surrounded by a small triangle. The positions are labeled with the respective time and connected by the course line.
According to DIN 13312 navigation; Terms, abbreviations, formula symbols, graphic symbols , in the case of a vehicle location determined with a location determination method, the intersection of the base lines - or the longitude and latitude line - is surrounded by a circle; Stance lines from the last observation have an arrowhead at each end; Radio base lines only have one arrowhead pointing away from the transmitter, which is jagged like a high-voltage arrow . The base line intersections of coupling locations are not circled. Sailed stand lines have double arrows at each end.
In recent years nautical charts have also been used increasingly outside of shipping. You will e.g. B. also used in the management of the increasingly important use of the sea (energy and raw material extraction). In the European Exclusive Economic Zones, the use of offshore wind energy is currently being expanded, and nautical charts are also used for planning and ensuring safety and rescue measures.
Nautical charts are usually sold flat because folded charts are imprecise. They are also stored flat in drawers or rolled up.
Digital nautical charts
A major disadvantage of traditional paper maps for shipping is the time-consuming updating of the maps using the ship's navigator . He must manually enter the most important nautical changes that are published regularly (usually once a week) in the news for seafarers by the card issuer. In the case of electronic systems, this unpopular and time-consuming work is done by updating the map data.
Printed nautical charts on paper are therefore increasingly being supplemented or even replaced on the ships by electronic nautical charts (ENC) that are used via ECDIS . The waiver of paper cards is, however, tied to very strict security requirements, as they are still fully operational even in the event of a complete failure of all systems on the ship and thus take on an important backup function. In mid-2005 the submarine USS Oklahoma City (SSN-723) was certified for the exclusive use of digital nautical charts as part of the Smart Ship Project .
The hydrographic services produce the ENC for their respective area according to uniform international standards, the distribution of these map data in vector format for use via ECDIS takes place exclusively via international data centers.
Digital chart data in raster format are sold commercially by all major chart publishers, but some are also available free of charge (e.g. for the USA from NOAA ).
The most important manufacturers of digital nautical charts for pleasure craft are Navionics, C-Map, Garmin and Navkom.
See also
- map
- Radio navigation
- Sea manual
- News for seafarers
- Bun bag navigation (joking)
- Development history of the nautical chart
- BSH ENC map viewer
literature
- Mathias Jonas: The international center for electronic nautical charts ensures the quality of ENCs . In: Schiff & Hafen , issue 12/2015, pp. 48–50
