NAV 44/7/8
Appendix F
Draft Advice on Electronic Chart Systems
ECS)
(Recommended by the mo Meeting on HGE
matters, 23-24 February 1998, as a replacement
to SN/Circ, 157 - January 1993))
1 INTRODUCTION
1.1 This advice is intended to assist
manufacturers in designing, and users in assessing and using,
an Electronic Chan System (ECS).
2. STATUS
2.1 The ECS is an aid to paper chart
which. when interfaced to a position-fixing system, displays
the ship's position together with chart information, and may
have the capability of combining other navigation-related
information such as radar.
2.2 The ECS is not equivalent to the
paper chart, and does not meet the requirement for ships to
carry and use up-to-date charts In accordance with Chapter V
of the 1974 SOLAS Convention.
3. CHART INFORMATION
3.1 The most up-to-date, detailed and
accurate data available for the intended application should
be used.
3.2 It must be possible to identify
the organization who has produced the digital chart data for
the ECS.
3.3 A means should be provided to
show the scale, or level of detail and accuracy, date of
issue and the originator of the source chart.
3.4 The geodetic datum of the chart
information should be available.
3.4.1 If the geodetic datum of the
chart is not WGS '84, the datum shift required to ensure
agreement between the chart and WGS '84 positions should
be given. A means to insert this shift should be provided
and a notice given when a position shift is in effect.
3.4.2 If either the datum or the
datum shift is not known, the mariner should be warned of
this.
3.4.3 The mariner should be aware
that discrepancies may exist between the chart and such
precise positioning systems as differential GPS. The
mariner should check far these as opportunity permits.
3.5 Mariners should be able to enter
chart corrections and their own notes manually. A means
should be provided of distinguishing this added information
from the chart database information on the display, The ECS
should provide a means of keeping a record of the corrections
applied.
3.6 An adequate updating service for the
chart database should be provided.
4. SCALE
4.1 An indication should be given if
the display scale selected is larger than the chart scale of
the source data.
4.2 A scale-bar, screen range, or
other indication of display scale should be provided.
5. DISPLAY OF OTHER NAVIGATIONAL
INFORMATION
5.1 The chart and any additional
information should match in scale and orientation.
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