Vector Chart Material; Introduction; S57 Charts - Furuno FEA-2107 Operator's Manual

8.

Vector Chart Material

8.1

Introduction

Theoretically a chart can be coded for use on a computer as raster or vector chart. Vector-coded charts are coded
using a variety of techniques. One technique is called S57ed3 and it has been chosen by IMO as the only alternative
for SOLAS compliant electronic charts. If an S57ed3-coded chart is published by a government-authorised
Hydrographic Office, then it is called "ENC". If an S57ed3-coded chart is published by a private firm, then it is
called "NON ENC". Another vector coding technique is known as CM-93/2, and it is employed by the private firm
C-MAP. All CM-93/2 charts are NON ENC. For further details about C-MAP charts, see Appendix 4. You can read
more about ENC and related legal issues in Chapter 7. Hereafter, all references to vector chart material are referred
to as "S57 charts" regardless of their source.
Sometimes you may wish to manually add Notices to Mariners or Navtex warnings into your S57 charts. This is
called "manual updates". Manual updates are valid for both S57 and ARCS charts so 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. For further details, see Chapter 10 "Manual Updates".
8.2

S57 Charts

8.2.1 Introduction
The electronic chart system is compatible with official IHO S57 release 3 chart material produced by Hydrographic
Offices (HO). This material, when issued by a 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 an 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 so the user needs a permit to view the ENC. This permit
could be entered manually from the control unit, loaded from a floppy disk or loaded through telecommunications
from an RENC.
Before any ENC can be used in the ECDIS, it is loaded into your 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 the electronic chart system, you control all date-dependent objects with
Display Until and Approve Until dates. In the 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 usage of updates in the
electronic chart 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.
Chart material will be stored in media such as CD ROMs and floppies, electronically through telecommunications
from RENCs or electronically from LAN (Local Area Network) in which it could have arrived from RENCs, CD
ROMs or floppies. Such material can contain only basic cells, cells and updates or only updates. The electronic chart
system contains as standard the software required to access CD ROMs, floppies and LAN. A telecommunications
package to establish a connection to an RENC in Stavanger, Norway, which operates using the marketing name
PRIMAR, is optionally available.
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