The BSH produces electronic navigational charts (ENCs) for its area of responsibility: the German territorial sea up to the border of the Exclusive Economic Zone, the Baltic Sea, and parts of the Southern Ocean. The ENCs contain all nautical chart information required for safe navigation. In addition, these digital charts contain supplementary information not found in the paper chart (for example: instructions for navigation). When used in a type-approved ECDIS, official ENCs and their updates may replace paper charts for navigation.
What is an ENC?
Electronic Navigational Chart (ENC) is the official term for official hydrographic vector data. They are produced in the uniform S-57 format defined by the IHO. S-57 data are projectionless data stored as geographic coordinates in WGS 84 (World Geodetic System 84). Each country produces ENC data for its area of responsibility: internal waters, territorial sea and continental shelf.
With the WEND concept (Worldwide Electronic Navigational Chart Database), the IHO is aiming to install a network for standardised ENCs that is tailored to the needs of international maritime traffic.
ENCs form the data basis for ECDIS (Electronic Chart Display and Information System) and are organised in so-called cells. These cover a rectangular sea area defined by geographical coordinates, with no overlapping areas within a scale range.
Navigation purpose and scale range
ENC cells are produced in different scale ranges with different degrees of generalisation (usage bands) depending on the navigation purpose. Each of these usage bands has its own key figure. If several cells with different usage bands for the same sea area are loaded into the ECDIS, the content of the usage band with the higher key figure (and the more detailed display) is shown. The content of the usage band below is no longer visible. The following usage bands exist:
|1||Overview (complete sea area; e.g. the entire Baltic Sea) |
|2||General (partial area; e.g. the German Bight)|
|6||Berthing (marina, (part of) the harbour area with moorings and anchorages) |
Designation of the cells
The S-57 file names are also designated in an international system. From the first 3 characters of the file name the nationality and the usage band can be derived. The remaining 5 digits are used to number the cell according to a BSH internal cell scheme. For example ENC "DE521500" was produced by the BSH (DE) and is intended for the usage band "Harbour" (5).
S-57 has been the official IHO standard since 1992. It contains the data model, the data structure and the object catalog as well as the product specifications. A data set that complies with this standard is called an electronic navigational chart (ENC).
The graphical presentation of data on an ECDIS system is done according to the IHO standard S-52. This standard provides guidelines for the output and updating of ENCs and the display in ECDIS. The instruction for symbolisation for each object on the screen is defined in a Presentation Library. This ensures that the objects are displayed on the color monitors of different manufacturers with correct uniform symbols and colors.
The decades-old S-57 standard no longer meets the requirements of the 21st century. For this reason, intensive work is being done on the successor standard S-101.
What is an ECDIS?
An ECDIS (Electronic Chart Display and Information System) consists of hardware, software and the digital data of the nautical chart as well as a various other information. It is a real-time navigation and information system that provides information on the respective conditions or provides the position of the own ship by means of GPS signals, but can also recognise and report obstructions. An ECDIS combines all essential navigation information and displays it in a complex way for the navigator.
The following data can be displayed on a single screen in ECDIS:
- Parts of the sailing directions, the nautical radio service and the list of lights
- Radar image or ARPA targets (Automated Radar Plotting Aid)
- Course line and current location of the ship
- Alphanumeric position and navigation data (planning data, current navigation data, recorded track information)
- AIS (Automatic Identification System) symbols
An ECDIS offers the following advantages:
- The navigator has all essential nautical information displayed on one screen. This allows him to pay more attention to the active navigation of the ship.
- The time-consuming manual correction of paper charts on board is no longer required. The database in an ECDIS is updated automatically from a data carrier or via satellite.
- ECDIS offers the function "Safety Contour". The "Safety Contour" is the depth contour indicating a depth range, which – depending on the draught of the ship – is sufficiently safe.
- The chart management in ECDIS ensures that the chart data available for the selected zoom level are always displayed.
- ECDIS offers the function "Watch Dog", which can monitor a defined area on the selected course and warn the navigator of hazards visually and acoustically.
- Safe and easy route planning is possible directly in ECDIS or via an import file. The system can perform a routine check and warns of obstructions on the route or in a defined corridor.
- An automated path guidance (route based steering) is part of the standard functionality of a modern ECDIS.
- Many ECDIS have a simulation function for planning difficult ship manoeuvres, e.g. mooring manoeuvres.
However, the functions of ECDIS briefly described here are only achieved with vector data. Therefore vector data are primarily used in ECDIS. Only where these are not available, it is possible to switch to raster data. A navigation system based exclusively on raster data is not recognised as a navigation aid by the IMO.
How do I acquire an ENC?
The IHO has developed a distribution system for ENCs. The hydrographic institutions (such as the BSH) deliver the produced ENCs to regional data centers for ENCs. The Regional Electronic Navigational Chart Coordinating Centres (RENCs) collect the ENCs, check whether the data complies with the S-57 Standard and deliver them encrypted according to the IHO Standard S-63 to authorised distributors (Value Added Reseller - VAR).
The responsible RENC for the BSH ENCs is the IC-ENC (International Centre for ENCs) in Taunton UK. The authorised distributors of the IC-ENC are AVCS, ChartCo, ChartWorld, C-Map, DATEMA, maris, NAVTOR and PRIMAR.