Definition;

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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISElectronic Chart Display and Information
System

• Definition
• Legal Aspects
• Numeric Cartography
• Vector Chart
• Raster Chart
• Official Charts (ENC, RNC).

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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDIS
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISElectronic Chart Display and Information
System
ECDIS An Electronic Chart Display and
Information System is a Geographic Information
System (GIS) that complies with International
Maritime Organization (IMO) regulations and can
be used in replacement of paper navigation
charts. GIS Computer-based technologies for
storage, manipulation, and analysis of
geographically referenced information. A
Geographic Information System differs from other
computerized information systems for the
following reasons 1. the information is
geographically referenced (geo-coded) 2. higher
capabilities for data analysis and scientific
modelling, in addition to the usual data input,
storage, retrieval, and output functions.
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISElectronic Chart Display and Information
System
The system displays information from electronic
navigational charts and integrates position
information from the Global Positioning System
(GPS) and other navigational sensors, such
as 1. Radar (Target and display on top) 2.
Echo-sounder 3. Gyro-compass 4. Wind sensors
5. Speed-Log 6. Automatic Identification
Systems (AIS). For these reasons ECDIS
represents a real time Geographical Information
System.
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISElectronic Chart Display and Information
System
C.P.U.
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISElectronic Chart Display and Information
System
The primary function of an ECDIS is to contribute
to safe navigation. IMPORTANT ECDIS IS AN
INSTRUMENT FOR SUPPORTING DECISION
PROCESS. There is a tendency to put too much
trust in computer based systems and believe
whatever is on the display (Over reliance on
ECDIS). It is essential that officers remember to
cross check the information displayed by all
other means available, especially by looking out
the window and watching the display. At the same
time the officer has to take care of the accuracy
of the integrated navigational sensors.
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ECDIS COURSE - Italian Maritime Academy
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ECDISInternational Organizations
To ensure that ECDIS equipment intended for
onboard use is seaworthy, it must pass type
approval and test procedures developed by the IEC
(International Electrotechnical Commission) based
on the ECDIS Performance Standards of IMO
(International Maritime Organization) and
applying the IHO (International Hydrographic
Organization) technical standards related to the
digital data format. Type approval is a method
to show conformance with IMO requirements on a
legal basis. It is initiated and required by all
Flag States which are Member States of the
European Union and by many others including
United States, Japan and Australia. ECDIS type
approval is the certification process that ECDIS
equipment must undergo before it will be
considered to comply with the IMO Performance
Standards for ECDIS by the international shipping
community.
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISInternational Organizations
IHO
IMO Performance Standards for ECDIS IMO Model
Course 1.27 SOLAS Convention STCW
S-52 Specifications for ECDIS App.1 Guidance on
Updating App.2 Colour and Symbol App.3 Glossary
of ECDIS-related Terms
S-57 Transfer Standard for Digital Hydrographic
Data
S-52 Specifications for ECDIS App.1 Guidance on
Updating App.2 Colour and Symbol App.3 Glossary
of ECDIS-related Terms
S-57 Transfer Standard for Digital Hydrographic
Data
IEC
IEC
Publication 61174 Maritime Navigation and
Radiocommunication Equipment and Systems -
Electronic Chart Display and Information System
(ECDIS) Operational and performance
requirements, methods of testing and required
test results.
Publication 61174 Maritime Navigation and
Radiocommunication Equipment and Systems -
Electronic Chart Display and Information System
(ECDIS) Operational and performance
requirements, methods of testing and required
test results.
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISLegacy Aspects IMO Performance Standards
There are two classes of navigational electronic
chart system 1. ECDIS, which meets the
IMO/SOLAS chart carriage requirements 2. ECS
(Electronic Chart System), which can be used to
assist navigation, but does not meet IMO/SOLAS
chart carriage requirements. ECDIS equipment is
specified in the IMO ECDIS PERFORMANCE
STANDARDS IMO Resolution A817(19) IMO
Resolution 232(82)Adoption of the revised
Performance Standards for ECDIS" as
follows Electronic Chart Display and
Information System (ECDIS) means a navigation
information system which, with adequate back up
arrangements, can be accepted as complying with
the up-to-date chart required by regulation V/19
V/27 of the 1974 SOLAS Convention
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISLegacy Aspects IMO Performance Standards
IMO SOLAS V/19 2.1 All ships irrespective of
size shall have () 2.1.4 nautical charts and
nautical publications to plan and display the
ships route for the intended voyage and to plot
and monitor positions throughout the voyage an
Electronic Chart Display and Information System
(ECDIS) may be accepted as meeting the chart
carriage requirements of this subparagraph 2.1.5
back-up arrangements to meet the functional
requirements of subparagraph 2.1.4, if this
function is partly or fully fulfilled by
electronic means An appropriate folio of
paper nautical charts may be used as a back-up
arrangement for ECDIS. Other back-up arrangements
for ECDIS are acceptable (see appendix 6 to
resolution A.817(19), as amended). IMO SOLAS
V/27 Nautical charts and nautical publications,
such as sailing directions, lists of lights,
notices to mariners, tide tables and all other
nautical publications necessary for the intended
voyage, shall be adequate and up to date.
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISLegacy Aspects Back Up Requirements
No electronic system is completely failsafe!
IMO Performance Standards therefore require
that the overall system include both a primary
ECDIS and an adequate independent back up
arrangement. IMO added Appendix 6 to the
performance standards for ECDIS back up
requirements, lists the required functions and
availability requirements of back up
arrangements, including Chart information
using the latest official edition that are kept
up-to-date for the entire voyage Route
planning capable of performing route planning
functions, including taking over the route plan
of the primary system, and adjusting a planned
route Route monitoring enabling take-over of
the route monitoring function originally
performed by the primary system, including
plotting own ships position and displaying the
planned route
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ECDIS COURSE - Italian Maritime Academy
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ECDISLegacy Aspects Back Up Requirements
Voyage recording that keeps a record of the
ships actual track, including positions and
corresponding times. The definition of these key
functional requirements still leaves open
technical solutions representing adequate back up
arrangements. Finally
A second ECDIS connected to an independent power
supply and a separate GPS position input
An appropriate up-to-date folio of official paper
charts for the intended voyage
An ECDIS operating in the RCDS mode of operation
Back Up Systems
A radar-based system called Chart-Radar
according to IMO Performance Standards for Chart
Radar
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISLegacy Aspects Back Up Requirements
France Acceptance of ECDIS Applies to all
vessels Maritime Authority provides
certification Backup Arrangements for ECDIS At
present the French Administration only authorises
paper charts to be used as a backup to
ECDIS Acceptance of RCDS Applies to all
vessels Maritime Authority provides
certification IMO or Flag State
Notifications Règlement annexé à larrêté du
23/11/1987, division 221 Website www.mer.gouv.f
r
IMO Circular Letter 2666 - Compendium of Flag
State ECDIS requirements
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISLegacy Aspects ENC
Electronic Navigational Chart (ENC) means the
database standardised as to content, structure
and format issued for use with ECDIS on the
authority of government-authorized hydrographic
offices. The ENC contains all the chart
information necessary for safe navigation, and
may contain supplementary information in addition
to that contained in the paper chart (e.g.
sailing directions), which may be considered
necessary for safe navigation.
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ECDIS COURSE - Italian Maritime Academy
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ECDIS Numeric Cartography
There are two types of Numeric Chart 1.
Vector 2. Raster The difference between them is
the data archiving modality.
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ECDIS COURSE - Italian Maritime Academy
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ECDISNumeric Cartography Vector Charts

• ENTITY
• Points are spatially stored using the
  coordinates. For example, a two-dimensional point
  is stored as (x1,y1)
• Lines are stored as a series of point pairs,
  where each pair represents a straight line
  segment, for example, (x1, y1) and (x2, y2)
  indicating a line from (x1, y1) to (x2, y2)
• Polylines are a connected sequence of lines
• Polygons are a connected sequence of lines where
  the first and the last points are coincident.

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ECDIS COURSE - Italian Maritime Academy
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ECDISNumeric Cartography Vector Charts
Y
ID X Y ATTRIBUTE
1 1 1.5
P1
Numeric Database
X

• Each entity type may have one or more attribute.
  Attributes may describes quantitative data ranked
  in 3 level of accuracy
• Ordinal (Ranks Good, Better, Best)
• Interval (Numeric Age, Income)
• Ratio (Scale Length, Area)
• Attributes may describes, also, qualitative data.

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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography Vector Charts
VECTOR DATA
ENTITY
ATTRIBUTE
Qualitative
Point
Line
Quantitative
Poligon
Polyline
Ordinal
Ratio
Interval
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography Vector Charts
For a building
ID (unique)
Attribute (qualitative)
Attribute (quantitative - Interval)
ID X Y Type Area (m2) Property Nb.
1 1 1.5 Industrial 400 40324
2 3 3 House 120 3546
.. ...
Coordinates
Attribute (quantitative - Ratio)
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography Vector Charts
Y
ID X Y ATTRIBUTE
1 1 1.5
P1
Numeric Database
X
Vector charts are generally manufactured from
scanned hydrographic office paper charts. The
scanned image is then digitised by tracing the
lines and features on the chart. 1. this
vectorisation process stores chart features in
layers (themes) which can be redrawn
automatically at an appropriate size as you zoom
into the chart. You can add or remove categories
of data such as spot depths, depth contours,
navigation marks, etc.
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography Vector Charts
2. you can query specific chart items (e.g. to
get more information on a navigation light) 3.
you can display the chart at a larger scale than
the source paper chart (without image
degradation). So it is very important to point
out the concept of Nominal Scale for Numeric
Chart. Remembering that Vector charts are
generally manufactured from scanned hydrographic
office paper charts, Nominal Scale is the scale
of the source paper chart. Pay attention we
can sail, for example, on a chart at 15000 with
a Nominal Scale of 150000. The metric
information and the chart data are from a 150000
scale chart 4. systems automatically decide on
the information to be displayed, depending on the
level of zoom.
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography Vector Charts

• VANTAGE
• Adding or removing layers of data
• Zooming and seeing more or less data appear
  according to the level of zoom
• Displaying the chart at a larger scale than the
  source paper chart
• Not large data volumes - Compact data structure.
• DISADVANTAGE
• The nature of the vector display is such that
  the chart data is not displayed electronically as
  it was compiled (as a paper document) and the
  original cartographic design of the paper chart
  is lost.

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ECDIS COURSE - Italian Maritime Academy
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ECDISIHO S57
To ensure that ECDIS function uniformly anywhere
in the world, the information elements contained
in the database must be consistent. It would make
non sense for each Hydrographic Office to develop
different types of chart objects. For this
reason the IHO (International Hydrographic
Organization) develop an Object Catalogue that
described the range of attributes to be assigned
to each object (www.S-57.com). As the key
component of the IHO Transfer Standard for
Digital Hydrographic Data (IHO S-57), the object
catalogue ensures that the database for ECDIS,
the Electronic Navigational Chart (ENC), is
properly constructed and organized. So
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISIHO S57
the IHO Transfer Data for Digital Hydrographic
Data (usually abbreviated as IHO S-57)
establishes the requirements for producing an ENC
to be used with an ECDIS satisfying the ECDIS
Performance Standard A817(19). It was completed
in November 1996 and published in March 1997 (a
new version has been published in 2000).
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISWEND (World-wide Electronic Navigational
Chart Data Base)
The Electronic Chart are produced under the
authority of a government organisation
(Hydrographic Organization). The user, then, can
obtain the ENCs from the various HOs directly.
This becomes prohibitively cumbersome if the user
engaged on international voyage. Therefore
service providers have been established which
collect the ENCs from different HOs and maybe
other sources, to deliver to the end user all
data he needs for his voyage. A particular
problem is to ensure that all official ENCs
produced by a large number of different HOs are
of the same quality. Without an additional
intervening mechanism ensuring uniform data
quality, Mariners would be left with
inconsistencies between ENCs from different HOs.
This the background why IHO has developed a
concept for a worldwide official ENC service.
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISWEND ECDIS Data Service

• The concept of an official data Service was
  developed in conjunction with the IMO
  requirements to establish a worldwide uniform
  updating service.
• An official ECDIS data service include
• Global Uniformity of data All participants must
  work in accordance with the same standard, i.e.
  S-57 data transfer standard. It must ensured that
  ENCs from all producing HOs worldwide exhibit
  consistent contents and display.
• Quickest way from the source to ECDIS This
  excludes any additional levels of processing.
  That is why the data must come directly from the
  originators. The Hydrographic Offices must have
  strict sharing of work in close co-operation.
  This ensures at the same time the global
  uniformity of data.

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ECDIS COURSE - Italian Maritime Academy
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ECDISWEND ECDIS Data Service
A reasonable solution is to have an arrangement
for sharing the work of setting up and
facilitating the provision of a world-wide ECDIS
data service based upon agreed upon
standard. This arrangement was established by the
IHO as the World-wide Electronic Navigational
Chart Data Base (WEND). The purpose of WEND is
to ensure a world-wide consistent level of high
quality, updated official ENCs trough integrated
services that support chart carriage requirements
of SOLAS Chapter V and requirements of the IMO
Performance Standards for ECDIS.
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ECDIS COURSE - Italian Maritime Academy
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ECDISWEND ECDIS Data Service - RENC

• WEND consists of two components to achieve its
  purpose
• A charter describes the principles governing the
  co-operation. This includes the following
  provisions
• By definition, the organization responsible for
  hydrographic survey of an area is also
  responsible for the ECDIS data
• The relevant ECDIS standards, especially S-57
  Edition 3 must be observed
• The rules and responsibilities for producing and
  validating the data.
• So called Regional Electronic Chart Co-ordinating
  Centres (RENC) which are organisational entities
  where IHO members have established co-operation
  amongst each other to guarantee a world-wide
  consistent level of high quality data, and for
  bringing about co-coordinated service with
  official ENCs and updates to them.

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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography Raster Charts
An exact replica of the paper chart
(scanner). The Raster Image is subdivided in
pixels, in a matrix of n lines and m columns.
Each pixel has a homogeneous and not sub
divisible contents.

• RADIOMETRIC RISOLUTION
• CROMATIC RISOLUTION (BPP)
• GEOMETRIC RISOLUTION (DPI)

Pixel
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography Vector and Raster
Charts
Raster
Vector
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography Official Charts

• Official electronic chart data and private chart
  data
• Official electronic chart data are of two general
  types
• Electronic Navigational Charts (ENC)
• Raster Navigational Charts (RNC).
• The inner construction of ENCs and RNCs is
  fundamentally different
• ENCs are vector charts
• RNCs are raster charts.
• The term Official, indicates that those chart
  data have been produced under the authority of a
  government organisation in contrast to private.

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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography ENC

• ENC means the database, standardized in the
  content, structure and format, issued for use
  with ECDIS on the authority of government-authoriz
  ed Hydrographic Offices.
• ENCs are vector charts compiled from a database
  of individual geo-referenced objects from
  Hydrographic Offices archives including existing
  paper charts.
• ENCs have the following attributes
• ENC content is based on source data or official
  charts of the responsible Hydrographic Office
• ENCs are compiled and coded according to
  international standards
• ENCs are referred to World Geodetic System 1984
  Datum (WGS84)
• ENC content is the responsibility and liability
  of the issuing Hydrographic Office
• ENCs are issued only by the responsible
  Hydrographic Office
• ENCs are regularly updated with official update
  information distributed digitally.

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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography ENC S52/S57

• In conjunction with the development of IMO
  Performance Standards for ECDIS, the
  International Hydrographic Organization has
  developed technical standards related to the
  digital data format, specifications for ECDIS
  content and display, and data protection.
• IHO Special Publication 52 (S-52) includes
  appendices describing the means/process for
  updating, colour and symbol specifications, and a
  glossary of ECDIS-related terms.
• IHO Special Publication 57 (S-57) includes a
  description of the data format, product
  specification for the production of ENC data, and
  an updating profile.
• Both IHO S-57 and S-52 are specified in the IMO
  Performance Standards for ECDIS.

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ECDIS COURSE - Italian Maritime Academy
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ECDISDisplaying ENCs by means of the
Presentation Library
ENCs dont contain any explicit visualisation
items. An ENC contains an abstract description of
geographic entities but does not contain any
presentation rules. All presentation rules to get
ENCs content displayed are contained in a
separate software module the so called
Presentation Library. Both the Geo-referenced
object contained in the ENC and the fitting
symbolization contained in the Presentation
Library are linked to each other only in the very
moment of their call up for display. The
definition of the Presentation Library for ENCs
is contained in Annex A of the IHO Special
Publication S52, Appendix 2 Colours Symbols
specifications for ECDIS.
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISDisplaying ENCs by means of the
Presentation Library
ENC Description of Geographic Entities (S57)
PRESENTATION LIBRARY Contains all presentation
rules (S52)
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography ENC/S63
A majority of all ENCs are only made available to
the end-users in a protected form compliant with
the IHO S-63 Data Protection scheme. The S-63
protection scheme defines a mechanism for
encrypting ENC information and applying a digital
signature to enable authentication of the chart
data by the end-user. The end-user will require a
decryption key to access and view the ENC data
protected by the scheme. Each ENC chart is
encrypted with a different key, and the
decryption keys are issued to specific end-user
systems and can consequently not be exchanged or
shared by different systems. A majority of all
ECDIS and ECS suppliers have developed support
for IHO S-63 and can read protected ENCs. A few
nations distribute their ENCs without using
encryption all ECDIS systems are able to access
and display these ENCs.
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography SENC
An ECDIS does not process the ENC content
directly for the matter of display. ENCs in S-57
format are optimised to absorb the Hydrographic
object information but this structure is not
adequate for the fast generation of the resulting
computer image on the screen. In order to get
efficient data structures that facilitate the
rapid display of ENC data, ECDIS firstly converts
each ENC from S-57 ENC format into an internal
format called SENC (System ENC) which is
optimised for chart image creating routines.
Such routines are not standardised they are
part of the individual software know-how of the
ECDIS manufacturers. Consequently the SENC format
differs between the ECDIS of different
manufacturers. In contrast to the common uniform
ENC format the SENC format is proprietary for
each ECDIS manufacturer.
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography SENC
ENCs in S-57 format have to be translated into
the internal data format or SENC (System
Electronic Navigational Chart) used by the ECDIS
before they can be displayed. The main SENC
formats are C-Map's CM-ENC (CM-93/3) format
supported by over 20 ECDIS manufacturers. The
most noticeable effect is the difference in
installation and updating time. Here are the
results of tests from 10 Things They Should Have
Told You About ECDIS
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ECDIS COURSE - Italian Maritime Academy
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ECDISNumeric Cartography SENC
Comparison between S-57 ENC and SENC installation
times (all available cells, Sept 06) S-57 ENC
format Disk copying (5 base CDs) 1.5
hours Decryption, verification and installation
11.2 hours Total 12.7 hours Apply Update CD 4.03
hours CM-ENC SENC format Disk copying (1 DVD)
13 mins Apply licence 5 mins Total 18 mins On
line update A few minutes
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography ENC/N.P.N.S.R.
During production, ENCs are assigned a
compilation scale based upon the nature of the
source data they are based on, and are allocated
to a navigational purpose band related to this.
As shown in the table below there are 6
navigational purpose bands (scale ranges are
indicative only). Navigational Purpose Name
Scale Range 1 Overview 2 General 3
Coastal 4 Approach 5 Harbour
6 Berthing
gt11 499 999 1350 000 11 499 999 190 000
1349 999 122 000 189 999 14 000 121
999 lt 14 000
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography ENC Code

• Each ENC is identified by an 8 character
  identifier e.g. FR501050
• The first two characters indicate the producer
  e.g FR for France, IT for Italy (a complete list
  of producer codes is included in the IHO standard
  S-62).
• The third character (a number from 1 to 6)
  indicates the navigational purpose band.
• The last 5 characters are alpha- numeric and
  provide a unique identifier.
• A Chart with a different code is an unofficial
  chart.

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ECDIS COURSE - Italian Maritime Academy
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ECDISNumeric Cartography ENC Code
ECDIS distinguishes an ENC from unofficial data.
When unofficial data is used, ECDIS informs
mariners that they must navigate by means of an
official, up to date, paper chart by a continuous
warning on the screen. If unofficial data is
shown on the ECDIS display, its boundary is to be
identified by a special line style. This boundary
is visualized as a one-sided RED line with the
diagonal stroke on the unofficial side of the
line.
ENC
Unofficial data chart
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ECDIS COURSE - Italian Maritime Academy
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ECDISNumeric Cartography Updating ENCs

• In principle the generation and distribution of
  regular updates uses identical organisational
  structures as for the production and distribution
  of ENCs described above. Their frequency is
  usually synchronised with the chart corrections
  promulgated with national Notice to Mariners for
  the affected sea areas.
• Updates may reach the ship via different ways
  depending from the capabilities of the service
  provider and the communication facilities
  onboard
• On data distribution media, e.g. CD
• As e-mail attachment via SATCOM and
• As broadcast message via SATCOM plus additional
  communication hardware.
• A number of ENC service providers already have
  updating services using e-mail and web and other
  means details may be obtained from ENC
  distributors.

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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography Updating ENCs
Updates to ENCs are sequential, and the sequence
is unique to each ENC. During the updating
process ECDIS always checks that all updates in
the sequence have been applied. If an update is
missing then the ECDIS will indicate this it is
not possible to load later updates until the
missing update is applied. The ECDIS maintains
a list of updates applied and the date of
application. Port State Control officers may
use the ECDIS listing to ensure that ENCs are
being kept up to date in accordance with SOLAS V
Regulation 27.
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography ENCs Coverage
The International Hydrographic Organisation (IHO)
provides an interactive web catalogue
(http//services.ecc.as/ihocc/public) displaying
the status of worldwide ENC production. This
system has pointers for guiding users to ENC
suppliers and distributors. It is also possible
to download the ENC catalogue information from
here as a comma separated file.
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ECDIS COURSE - Italian Maritime Academy
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ECDISNumeric Cartography ENC
In order to replace paper charts The chart data
in use must be official - ENCs where these are
available. What to do in areas without ENC
coverage?
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ECDIS COURSE - Italian Maritime Academy
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ECDISNumeric Cartography RNC/RCDS

• RNC means Raster Navigational Chart. RNCs are
  digital raster copies of official paper charts
  conforming to IHO Product Specifications RNC
  (S-61). By definition RNCs can only be issued by,
  or on the authority of, a national Hydrographic
  Office.
• RNCs have the following attributes
• RNCs are a facsimile of official paper charts
• RNCs are produced according to international
  standards
• RNC content is the responsibility of the issuing
  Hydrographic Office and
• RNCs are regularly updated with official update
  information distributed digitally.

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ECDIS COURSE - Italian Maritime Academy
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ECDISNumeric Cartography RNC/RCDS
In 1998 the IMO recognised that it would take
some years to complete the worlds coverage of
ENCs. As a consequence IMO ECDIS Performance
Standards were amended adding a new optional mode
of operation of ECDIS, the Raster Chart Display
System (RCDS) mode. In this mode RNCs can be
used in ECDIS to meet SOLAS carriage requirements
for nautical charts. However, this is only
allowed if approved by the Flag State. The
intention of those changes was to allow the ECDIS
to operate as far as possible on official chart
data ENCs where they were available and RNCs to
fill in the gaps. IMO took note of the
limitations of RNCs as compared to ENCs (see IMO
SN Circular 207 at Annex), and the revised ECDIS
Performance Standards require that the ECDIS must
be used together with an appropriate folio of up
to date paper charts for the areas where RCDS
mode is employed.
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ECDIS COURSE - Italian Maritime Academy
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ECDISNumeric Cartography RNC/RCDS
The intention was to allow the number of paper
charts carried by a vessel to be reduced where
RCDS mode was employed, but only to a level
compatible with safe navigation. No definition of
an appropriate folio was provided by IMO and
consequently different Flag States developed
individual interpretations. As there is no
common interpretation of the term appropriate
ship owners should consult their Flag State as to
whether RCDS mode is allowed and under what
conditions.
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ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography RNC/RCDS
There are two official raster chart formats
(RNC) 1. ARCS (UK HO) and Seafarer (Australian
HO) both produced in the UK HOs proprietary HCRF
format. ARCS is updated weekly with the same
information as the weekly Notice to Mariners used
to correct BA paper charts. Seafarer is updated
monthly on a similar basis. 2. BSB raster
charts contain all the detail found in NOAA paper
charts, with updates published every 30 days.
Weekly Notice to Mariner updates will be
available in the second quarter of 1998. These
will be distributed via the Internet and will be
completely in-sync with the US Coast Guard, NIMA
and Canadian notices (free from NOAA web site).
CHS
53
an appropriate portfolio of up to date paper
nautical charts
54
ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography RNC/RCDS
55
ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography RNC/RCDS
56
ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography RNC/RCDS
57
ECDIS COURSE - Italian Maritime Academy
Technologies
ECDISNumeric Cartography RNC/RCDS