ECDIS stands for Electronic Chart Display and Information System

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ECDIS

ECDIS stands for Electronic Chart Display and Information System.  It is an Electronic Navigational Chart with positionalinformation plus additional navigation-related information in a system toassist in navigation.

SOLAS 1974
      
Paragraph 2.1.4 of Regulation V/19 states that:

“All ships, irrespective of size, shall have:
Nautical charts and nautical publications……… toplan and display the positions throughout the voyage; ………. An ECDIS maybe accepted as meeting the chart carriage requirements of this subparagraph…”

Convention ships may be fitted with an ECDIS system with a back-upsystem (either an electronic back-up system or with appropriate paper chartsfor the intended voyage).

2000 HSC Code

Recently, IMOissued MSC Circulars 221 (82) and 222(82) about amendments which have been adopted to both 1994 HSC Code and 2000 HSCCode.  New paragraph 13.8.2 is tobe added in Chapter 13 of the 2000 HSCCode under the title “ShipboardNavigational Systems and Equipment and Voyage Data Recorders” which states that:

“High-speed craft shall be fitted with an ECDIS asfollows:

  1.      craftconstructed on or after 1 July 2008;

2. craftconstructed before 1 July 2008, not later than 1 July 2010.”

In this regard, high speed craft shall be fitted with an on board ECDISsystem to provide continuous position monitoring during the voyage to assistthe master and navigators with the safe navigation of the vessel.

STCW 95

An officer who is in charge of a navigational watch on board a ship of500 GRT or more should attainedthe minimum standard of competence specified in Table AII/1 of STCW Code. Thecompetence includes “Plan and conduct a passage and determine position” of thevessel, in which he should have thorough knowledge of and ability to usenavigational charts andpublications, NTM, radio navigational warnings and ships’ routeing information.

Note:  ECDIS systems areconsidered to be included under the term “charts”.

International Standards

There are a number of InternationalStandards which ECDIS shall meet:

•           International Hydrographic Organization (IHO)transfer Standard for Digital Hydrographic Data S- 57,

•           IHO Specifications for Chart Content and Displayaspects of ECDIS S- 52,

•           IMO Resolution A.817 (19) Performance Standards forECDIS, and

•           International Electrotechnical Commission (IEC)61174: ECDIS - Operational and performance requirements, methods of testing andrequired test results.

IMO Resolution A.817 (19) - Performance Standards forECDIS

       Someof the requirements stated in the Performance Standards for ECDIS are asfollowing: -

1.         ECDIS should haveadequate back-up arrangements (Duplication of the system or carriage ofappropriate paper charts for the intended voyage) ;

2.         ECDIS should be capableof displaying all chart information necessary for safe and efficient navigation;

3.         ECDIS should facilitatesimple and reliable updating of the electronic navigational chart ;

4.         ECDIS should reduce thenavigational workload compared to using the paper chart ;

5.         ECDIS should have atleast the same reliability and availability of presentation as the paper chart;

6.         ECDIS should provideappropriate alarms or indications with respect to the information displayed ormalfunction of the equipment.

The ECDIS enables the user to call up information on the items displayedin addition to the graphics presentation. For example, a lighthouse is markedon the chart by a tower symbol or a traditional chart symbol if the userprefers.  The system can give furtherinformation on this subject about the characteristic and detail of thelighthouse similar to the information printed in the List of Lights.

The ECDIS uses the Electronic Navigation Chart (ENC)which is the ship’s electronic chart database. The ENC contains all thechart information necessary for safe navigation and may contain nauticalinformation in addition to that contained in the paper chart (e.g. SailingDirections).

The digital chart (i.e. ENC)database is maintained by the National Hydrographic Authority.  In Hong Kong,the authority is the Hydrographic Office of Marine Department, HKSAR.

RESOLUTION MSC. 232(82)

This resolution is adopted on 5 December 2006 and will beimplemented on 1.1.2009.  The Annex 24 ofthe resolution - THE REVISED PERFORMANCE STANDARDS FOR ELECTRONIC CHART DISPLAYAND INFORMATION SYSTEMS (ECDIS)which the Raster Chart Display System (RCDS or ECD) using Raster Navigational Charts(RNC) is incorporated in the Standards to meet the real situation.

System ElectronicNavigational Chart (SENC)

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The SENC is the database that is actually accessed by the ECDIS fordisplay generation and other navigational functions.  The database is resulting from thetransformation of the ENC by theECDIS for appropriate use. Update to the ENCby appropriate means, and other data added by the mariners.  The SENC contains the equivalent to anup-to-date paper chart. The SENC may also contain information from othersources.

















Characteristic of ECDIS

The ENC data is the onlydata of IHO S-57 standards transformed into the ECDIS for display and use.  The standardized colour and symbol isrequired in accordance with IHO S-52 standards. The updating of the ENCpromulgated through NTM is easy and can be done automatically onboard ship reducingthe time consuming workload manual correction of paper charts.  The scale in display the ENC can be changed by the user freely by means ofthe display scale.  Additionalnavigational-related information depends on the layer of display can bemanipulated by the user. These are: Base, Standard and All.   TheECDIS is a sophisticated navigational system that provides alarms or indicationswith regard to preset safety paramaters, e.g. safe depth, safe contouretc.  Other navigational sources such asGlobal Navigational Satellite System (GNSS/GPS), Automatic Identification System (AIS) andRadar and ARPA picture, etc. can be overlaid on the ECDIS screen for navigationpurpose.

Types of Electronic Charts

Not all electronic charts are in same format; many different formatsexist for electronic charts.  However, twomajor types are now in use on merchant ships, they are vector chart and rastercharts.  Raster charts (RNC), in fact,are scanned paper charts into the pictures with adjustment made suitablefor display on the RCDS.  This RNC isalso known as Admiralty Raster Chart System (ARCS Charts) which produced by theBritish Admiralty.

Vector charts are digitized charts. Countries are producingunique digital charts based on their interpretation of IHO standards (i.e. S-57standards)

Raster Chart (RNC)	Vector  Chart (ENC)
Chart data is a digitized “picture” of a  chart.  All data in one layer and one format.      With raster data, it is difficult to change  individual element of the chart since they are not separated in the data  file.	Chart data is organised into many separate files. It contains layer  information to produce certain symbols, lines, area, colours, and other  elements.      With vector data, it can change individual elements with additional  data.

The differences betweenRNC/ARCS (RCDS) or (ECS) and ENC (ECDIS)

RNC (RCDS or ECS)

ENC (ECDIS)

•           Chart based system similar to paper charts.    •           Will not trigger automatic alarms.  Some alarm can be generated from  user-inserted information.    •           Chart projection may differ between RNCs.    •           Chart horizontal datum relates to the datum of  the position fixing system, may appear as a shift in position.    •           Feature cannot be simplified or removed to suit a  particular navigational circumstance. This affects the superimposed of  radar/ARPA picture.    •           Cannot select different scale charts.    •           May affect the readability of chart text and  symbols.    •           Not possible to gain additional information.    •           Not possible to display a ship’s safety contour  or safety depth.    •           Different colours may be used to show similar  chart information.    •           Displayed at the scale of the paper chart.  Excessive zooming in or out can seriously  degrade RCDS capability.    •           In confined waters, the accuracy of chart data  may be less than that of the position fixing system in use.

•           No chart boundaries.    •           Will trigger automatic alarms.

Alarms/Warnings

ECDIS provide Warnings and Alarms. It combines several different functions into one computerized system whichis possible to provide alarms or display warnings (indication) when certainparameters are met or exceeded as determine by the navigator.

Types of Warning

• Deviating     from a planned route;
• Approach to     waypoints;
• Failure of     the positioning system;
• Vessel     crossing safety contour and;
• System     malfunction or failure etc.
  

When to use ECDIS or RCDS ?

As the ENC is developed and producedby countries, it is not distributed by one stop shops like the distribution ofpaper charts, henc ships using ENCand RNC is common nowadays.  Therefore ECDIScan operate in two modes:

•         The ECDIS mode when ENC data is used,

•         The RCDS mode when ENC data is not available.

NOTE: When RCDS mode is in use, the back-up system is the portfolio ofappropriate paper charts for the intended voyage.

Components of ECDIS

ECDIS represents an item of equipment consisting of hardware, softwareand data.  Whilst a high performance PCor workstation installed in a console linked with other items of ship’sequipment, such as:

•           Course to steer linked with Gyro compass

•           Rate of turn linked with a turn indicator

•           Speed and distance linked with log

•           Ship position is fed from the GNSS/GPS

•           Radar data overlaid from source of radar.

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Advantages over Paper Chart

ECDIS is not only an adequate replacement for the paper navigationalchart but also a system containing all information important for navigation.  It reduces the time-consuming manualcorrection of paper charts.

The ECDIS display can be superimposed with radar images and with theradar targets of ARPA; and the vessel’s positions is continuously shown on thechart display and stored at regular intervals. Hence manual chart exchange is no longer required.

The elements of route planning in ECDIS are waypoints and leglines to ensuringsafe track keeping.  The cross distancealong the leglines can be set for activation of the alarm if the vesseldeviates from the scope of leglines.  ECDIS"knows" whether a vessel can pass safely through an area, on thebasis of the vessel's information fed in.

The Risks of ECDIS

It should be noted that the ECDIS is only a tool thathelps a mariner safely and effectively navigate a ship.  One of the biggest risks with the transitionto ECDIS is an over reliance in the information provided.

Limitation of ECDIS

There are some limitations of the ECDIS as followings:

1.      Chart Accuracy

ECDIS provides the navigator with a tactical toolwhich incorporates a high accuracy positioning device.  The navigator can "zoom" in on anECDIS chart to a scale beyond the intended accuracy of the charted information.

• Technical     limitation of other devices
  

The accuracy is also depends on the technicallimitation of other devices linked to the ECDIS, such as GPS, radar, etc. The mariner must be attentive to the source and accuracy of the positionfixing device utilized by the ECDIS.
                                          
3.  InformationOverload

The mariner is cautioned to be wary of information overloadand a very cluttered display screen. Information overload and a clutteredscreen seriously degrade navigation safety for the mariner and could result ina "technology-assisted incident".

• Familiarization     of ECDIS
  

A mariner must invest time and effort to masteringthe device prior to his first navigational watch.  This will be crucial to the navigation safetyof the vessel in the event paper charts are not required or available on thevessel.

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