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Vector Chart material
Introduction
Theoretically a chart can be coded for computer as raster or vector chart. There is a special chapter for raster coded
charts in this manual. Vector coded charts can be coded using different techniques. One technique is called S57ed3
and this technique has been selected by IMO as the only alternative for SOLAS compliant electronic charts. If a
S57ed3 coded chart is published by government authorised Hydrographic Office, then it is called ENC. If a S57ed3
coded chart is published by private industry, then it is called as NON ENC. Another technique is known as CM-
93/2. It is used by private company C-MAP to publish electronic charts. All CM-93/2 charts are NON ENC. There
is a special chapter about C-MAP charts in this manual. You can read more about ENC and related legal issues in
chapter "Conditions required to replace paper charts". Later in this manual all references to Vector Chart material
are under name S57 Charts regardless of the source of them.
Sometimes you may wish to add manually Notices to mariners or Navtex warnings into your S57 charts. In this
system this kind of things are called as Manual Updates. Manual updates are valid for both S57 and ARCS charts so
that you need to define them only once. Also manual updates are valid for all scales so that you don't need to repeat
them for charts published in different scales from the same area. See more details in chapter "Manual Updates" .
S57 Charts
Introduction
This Electronic Chart System is compatible with official IHO S57 release 3 chart material produced by
Hydrographic offices (HO). This material, when issued by government authorised Hydrographic Office, is called
ENC (electronic navigational chart). Use, presentation and display of S57 charts are based on International
Maritime Organisation (IMO), International Hydrographic Organisation (IHO) and International Electrotechnical
Commission (IEC) regulations and rules (S52ed3.1). When this ECS (Electronic Charts System) uses ENC (S57
release 3 chart produced by a government authorised Hydrographic Office), it is an ECDIS as defined by IMO, IHO
and IEC.
An ENC could be encrypted to prevent unauthorised use and then the user needs a permit to view the ENC. This
permit could be entered manually from control panel, loaded from a floppy disk or loaded through
telecommunication from a RENC.
Before any ENC can be used in the ECDIS, it is loaded into the hard disk and converted into the system's own
internal format (SENC). Some parts of the charts may be date dependent i.e. they are visible after a set date or they
are visible only for a limited period etc. In this Electronic Charts System you control all date dependent objects with
Display Until and Approve Until dates. In paper chart world the Preliminary and Temporary Notices to Mariners
represent the date dependency described above for S57 charts.
An important part of ENCs are the updates. Hydrographic Offices can issue two kinds of updates:
•
incremental updates, which are small additions to original base cells
•
reissues and new editions, which are complete replacements of previous base cells and their
updates
All updates are date stamped and they may also contain date dependent parts. You control also usage of updates in
this Electronic Charts System from Display Until and Approve Until dates. Using Display Until and Approve Until
dates you can view your charts correctly drawn on any date in the past or in the future.
50 • • • • Vector Chart material
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