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What is ENC ?
The BSH's nautical information service produces electronic navigational charts
(ENCs) for the entire German North and Baltic Sea coast, using exclusively the
S-57 vector format. An ENC consists of geometric as well as alphanumerical data.
Presently, ENCs are produced on the basis of paper charts, i.e. the contents
of an ENC are largely identical with those of the analogue nautical chart. However,
the ENC limits mostly do not correspond to the sheet lines of the paper chart.
All ENCs are based on the World Geodetic System 84 (WGS84). ENCs constitute
the database for ECDIS. They are organized in so-called cells.
The cells are allocated to defined scale ranges with a different degree of
generalization, so-called usage bands. Each usage band has a special number.
Depending on the navigational situation, the following cells are available:
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Overview (small-scale overview)
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1
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General (medium-scale overview)
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2
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Coastal
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3
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Approach
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4
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Harbour
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5
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Berthing
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6
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The cell contents of a usage band do not overlap. If several cells of different
usage bands are loaded into ECDIS for the same sea area, the contents of the
usage band with the higher number is shown.
The contents of the subjacent
usage band is "cut out". The cell designation indicates the
nationality and usage band, e.g.
DE321002 is the name of the cell "Waters South of Helgoland".
DE
is the nationality: Germany
3 indicates the usage band: Coastal.
The remaining five digits number the cell.
The first three digits for
nationality and usage band are internationally defined.
Each national Hydrographic
Office has its own cell scheme.
ENCs are updated on a weekly basis. New Editions are produced in case of
major changes.
International Standards
IHO (International Hydrographic Organization) in Monaco and IMO (International
Maritime Organization in London) have developed international standards for
the production of ECDIS data as well as for their updating and display on board
ships.
The ECDIS data of the BSH are produced in accordance with the IHO Standard
for Digital Hydrographic Data Special Publication No. 57 (S-57).
A data set
produced according to the S-57 standard is called an Electronic Navigational
Chart (ENC).
S-57 was adopted as official IHO standard by the 14th International
Hydrographic Conference in Monaco in May 1992.
The present version 3.1 was developed by the Transfer Standard Maintenance
and Application Development Working Group (TSMAD) of the IHO Committee on Hydrographic
Requirements for Information Systems (CHRIS) and has been valid since November
2000.
Clarifications on the standard and information about modifications
to be made in the next version are published in the Cumulative Maintenance Documents.
A catalogue of object classes describes all objects occurring in ENCs (e.g.
buoys, depth contours) by indicating their geometry (point, line, and area)
and attributes (e.g. form and colour).
Another important standard of IHO, Special Publication No. 52 (S-52), describes
all hydrographic objects on an ECDIS display screen.
Standard S-52 is the
specification for the issue and updating of ENCs and their display in ECDIS
systems.
Instructions for screen symbolization of each object are given in
a Presentation Library.
Precise instructions are given for colour calibration
to make sure that objects look the same on the colour screens of different manufacturers.
Information
about ECDIS
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