Thursday 19 September 2019

Electronic Chart Display and Information System (ECDIS)


ECDIS IS AN ANTI-GROUNDING TOOL


  • ECDIS can be used as an Anti-Grounding Tool 
  • ECDIS can be used as a very effective Anti-Grounding tool when properly set up and used along with appropriate sensors.
  •  The vessels position can be continuously monitored on screen. This facility combined with Radar Overlay and PI function can assist the navigator in continuous cross-verification of vessel position by alternate means (GNSS / RADAR) 
  • On ENC's alarms can be generated well before the vessel would run into any danger.
  •  In narrow and congested waters the picture provided by the ECDIS can effectively influence the action taken onboard by the navigator difference between a vessel aground (or) afloat.
  • Positive identification of landmarks / Buoys / Navigational Aids / Vessel targets in conjunction with RADAR, Overlay to ascertain the quality of sensor input (Position/ Echo Sounder/etc.)  Use of true vector, Radar Overlay & Echo Sounder alarms can effectively help navigate safely under heavy weather /tidal conditions where vessels are experiencing severe set.


 IMO Performance Standard for ECDIS equipment 


 As per IMO performance standards, an ECDIS should have the min.inputs of

  • An Electronic Position Fixing System (EPFS)
  • To a gyrocompass (HEADING)
  • To a speed and distance measuring device (SPEED)

For any ship without a gyrocompass, ECDIS should be connected to a marine transmitting heading device. However, most modern ECDIS already integrate the majority of navigational systems on modern bridges but are subject to the condition that their integration does not degrade the performance of   ECDIS itself or any equipment providing sensor inputs. The benefits of integrating additional navigational systems will increase situational awareness. The navigation officer's workload decreases as information relating to the safe, navigation of the ship can be readily viewed on the ECDIS display as well as other important information.

Other Interfaced Systems

Following are the additional navigation systems incorporated into ECDIS can include but are not limited to
  1. RADAR
  2. AIS
  3. NAVTEX
  4. BNWAS
  5. Echo Sounder
  6. Meteorological Instruments



  

In this Performance Standard the definitions of Indicators and Alarms provided in the IMO resolution A.830(19)  “Code on Alarms & Indicators”(IMO-867E) apply


Alarm: An alarm or alarm system which announces by audible means or audible and visual means, a condition requiring attention.


Indicator : Visual indication giving information about the condition of a system or equipment.


 (For Ref.: http://www.imo.org/en/KnowledgeCentre/IndexofIMOResolutions/Maritime-Safety-Committee-(MSC)/Documents/MSC.232(82).pdf )*Page 17

ECDIS STANDARD

The IHO has the responsibility for standardizing the digital chart objects for ECDIS. The IHO has drawn up a model, an Object catalogue and an ENC product specification (PS) as standard for ECDIS data & published these in its SPECIAL Publication No.57 (S57)

IHO
International Hydrographic Office
Specification for Chart Content & Display Aspects of ECDIS
S-52 Edition 6.1 – Oct 2014
Presentation Library
S-52 Annex A Edition 4.0 – Oct 2014
Test Data Sets for ECDIS
S-64 Edition 3.0 – Dec 2014
Data Protection Scheme
S-63 Edition 1.2 – Jan 2015
IEC
International Electro-technical Commission
ECDIS – Operational & Performance Reqt., methods   of testing & required test results
   IEC 61174 Edition 4.0 – Sep 2015
Presentation of navigation-related information on shipborne navigational displays – General requirements, methods of testing & required test results
IEC 62288 Edition 2.0 – July 2014

               ECDIS CARRIAGE REQUIREMENTS
 

SHIP TYPE
SIZE
NEW SHIP
EXISTING SHIP
         TANKERS
≥ 3,000 GRT
1st July 2012
No later than 1stsurvey after 1 July 2015
  PASSENGER SHIPS
≥ 500 GRT
1ST July 2012
No later than 1stsurvey after 1 July 2014
                                   
                               DRY CARGO SHIPS


≥ 50,000 GRT
1ST July 2013
No later than 1stsurvey after 1 July 2016
≥ 20,000 GRT      (New ships)

20-50,000 GRT
(Existing Ships)
1st July 2013
No later than 1stsurvey after 1 July 2017
≥10,000 GRT
(New Ships)

10-20,000 GRT
(Existing Ships)
1st July 2013
No later than 1stSurvey after 1 July   2018
3-10,000 GRT
1st July 2014
No retrofit requirements to existing ships <10,000GRT

The RISK associated  with ECDIS 


   The Navigators may become dependent monitoring and that when a sensor fails, the navigator must return to first principles to deal with the situation. This, in turn, may lead the navigator to incur additional errors in dealing with Situation known as 

KNOWLEDGE-BASED ERRORS. 



COMPONENTS OF ECDIS
HARDWARE
SOFTWARE
DATA

    Hardware

      Complying with the IEC-61174 should be Type-Approved.
     It is the console(PC) should be connected with other ship’s equipment.

    Software

    As per IMO performance standards, It has user Interface and software called ECDIS-KERNEL, which make it possible to read & display a chart.

    Data

      There are two types of electronic charts(ENC & SENC) in ECDIS and all navigational officers should be aware of their difference and limitations.

     Electronic Navigational Charts (ENC)

     ENC commonly referred to as Vector charts, are layered with digital information enabling the mariner to electronically interrogate features on the chart such as buoys, navigational marks, TSS and Safety contours with elaborated information displayed for the user. 
    SENC

      It is generated from the original data of the ENC. The ENC has to be kept unaltered in order to able to reconstruct the SENC data if this is unintentionally damaged or destroyed. In SENC, the chart data is stored as a proprietary file format designed by the ECDIS manufacturer for speed and reliability.


    ALARM MANAGEMENT 


     ECDIS Alarm Management is very critical as

    • The level of control over alarms may differ from being very detailed control to minimal control
    • Some manufacturers may allow the mandatory alarms to be disabled
    • some even close choice of chart scale for alarm checking
    • It may vary from manufacturer to manufacturer 



      MANDATORY ALARMS


       Alarms are indicated by audible means or visual means indicating a condition requiring attention
      1. Crossing Safety Contour
      2. Position System Failure
      3. Deviation from Route
      4. Different Geodetic Datum
      5. Approach to Critical Point

        • The Guard zone (Safety Frame) provides the user with an advance warning of dangers/cautions.
        • The Navigational Alarms can include such hazards as SHALLOW DEPTHS, SHOALS & ISOLATED DANGERS as well as a minimum UKC (Ex. Anti-Grounding Alarm)

        ECDIS as an Anti-Grounding Tool



        • ECDIS can be used as a very effective Anti- Grounding tool when properly set up and used along with appropriate sensors.
        • The vessels position can be continuously monitored on screen. This facility combined with 
        • On ENC’s alarms can be generated well before the vessel would run into any danger.
        • In narrow and congested waters the picture by the ECDIS can effectively influence the action taken onboard by the ..... Difference between a vessel aground (or) afloat.
        • Positive identification of landmarks / navigational aids /buoys/vessels in conjunction with RADAR Overlay to ascertain the quality of sensor input (Position / Echo Sounder / etc.)
        • Use of true vector, RADAR Overlay &  Echo Sounder alarms can effectively help navigate safely under / tidal conditions where vessels are experiencing severe set.
        NAVIGATIONAL TOOL

        The concept of navigating entirely on electronic medium is relatively new even though there have been equipments available in the market for quite a while.In this scenario it is essential that mariners are aware of the fact that whatever activities that were carried out on paper charts can be carried out on electronic charts and additional functions are available which could not have been done on paper charts

        •  ECDIS is more than a digital version of a paper chart
        •  ECDIS is a complete change from using paper charts
        •  Navigating with ECDIS is  differ fundamentally from navigating with paper charts
        •  ECDIS shows all information on one semen
        •  Up-to-date information
        •  Integrating additional services (e.g.   RADAR,  ARPA, etc.)
        •  Enables passage planning, passage monitoring
        •  Enables quick response to emergencies (SAR)  optional
        •  ECDIS if properly used can increase the safety of navigation
        •  It is a complex tool if used in ignorance, and it can actually lead to increase risks
        • While plotting of position is carried out automatically on the ECDIS with input from sensors. Additionally, manual fixes are made by the user to counter check the accuracy as well as back-up in case of electronic position fixing system failure
        • Additionally facilities like weather routeing on a real-time basis, NAVTEX inputs etc., will make it an invaluable tool in the hands of a prudent mariner
        •   Passage planning tools like quick distance / ETA calculators, tide calculators, trial manoeuvres and prevalent currents for the season will make ECDIS an invaluable passage  planning / Voyage monitoring tool.
        • With availability of user chart layers (For carrying out corrections, additional remarks for passage planning. etc.) the navigator who is in charge of planning the passage can save a lot  of time and efforts all the while planning a perfect passage

        ENC DISPLAY (OR) LAYER CATEGORIES


        1. BASE
        2. STANDARD
        3. CUSTOM
        4. FULL

        DISPLAY BASE : (No Info. Can be added, not recommended for navigation)

        • Display base means the level of SENC information which cannot be removed from the display, consisting of information which is required at all times in all geographical areas and all circumstances. 
        • If is not intended to de sufficient for safe navigation.

          Display base consists of the following:-
          1.  Coastline (high water)
          2.  Ownship's safety contour, depth as set
          3.  Indication of isolated underwater dangers at depths of less than the safety contour which located within the safe waters defined by the safety contour
          4. Indication of isolated dangers which be within the safe water defined by the safety      contours such as  overhead wires, bridges, including buoys and beacons whether or not these are being used as aids to navigations
          5. Traffic routeing systems
          6. Scale, range, orientation and display mode
          7. Units of depth.

          STANDARD DISPLAY (SENC info shown, when the chart is displayed in any level of info can be added)

          • Standard Display means the SENC information that should be shown when a chart is first displayed on ECDIS (when switching ON). The level of the information it provides for route planning or  monitoring may be modified by the mariner according to the mariner's needs.
          The standard display consists of the following:-
          1. Indication of fixed and floating aids to navigation
          2. Drying line
          3. Boundaries of fairways. channels, etc.
          4. Visual and radar conspicuous features
          5. Prohibited and restricted areas
          6. Chart scale boundaries
          7. Indication of cautionary notes

          Custom display (Depends on User Requirements)

          1.  Spot soundings
          2.  Submarine Cables and pipelines
          3.  Details of all Isolated Dangers
          4.  Details of aids to navigation
          5. Contents of Cautionary notes
          6. ENC edition date
          7. Most recent chart update number
          8.  Magnetic Variation
          9.  Graticule
          10.  Place Names


          Full Display (too much info.)

                                                           SAFETY SETTINGS
           


          Safety Contours

          • The safety contour provides a visible boundary between “safe” and “unsafe” waler with respect to depth. and it enables easy identification by highlighting on the display. 
          • It is selected by the navigator to reflect a ship's draught, adjusted for the required under keel clearance and for the height of the tide if required. Depth contours on an ENC are varying as per the Hydrographic Office issuing the ENC . 
          • The system automatically uses ae the selected contour depth lies between contours.
          Safety Depth

          • The depth defined by the mariner, eg. the ship's draft plus required under keel clearance, to be used by the ECDIS to emphasize soundings on the display equal to or less than this value. 
          • The safety depth applicable to spot soundings, the depth of which is insufficient for a vessel to safely pass over.
          • Spot soundings less than the safety depth which are highlighted in bold type to indicate more accurate representation of a vessel's ‘no-go’ line than the safety contour.

           Safety Depth = Ship’s Draft + Squat + UKC+ CATZOC



          Shallow and Deep Contours

          • The shallow and deep contours are utilized when the multicolour depth display is selected. The deep contour is normally set at twice a vessel's draught to indicate when the squat is likely to be experienced. 
          • The area between the 0-m contour and the shallow contour is coloured light blue, and the area between the safety contour and the deep contour is coloured grey
          • This allows the gradient of the seabed to be graphically displayed.
          • All of the area between the 0-m contour and the safety contour is also marked by means of diamonds shaped pattern (shallow Pattern) 

            Shallow Contour = Ship’s Draft+ Squat


            Deep Contour = 2* Ship’s Deepest Draft



            CATEGORY ZONE OF CONFIDENCE (CATZOC)

            • Category Zone of Confidence (CATZOC) values are assigned to geographical areas to indicate whether data meets a minimum set of criteria for position, depth accuracy and seafloor coverage. The Zone of Confidence (ZOC) value is dependent on the positional and depth accuracy of the survey.
            • By understanding the accuracy limitations of the underlying data in greater detail, the mariner can manage the level of risk when navigating in a particular area.​
            • ECDIS display these CATZOC values in ENCs using a triangular or lozenge shaped symbol pattern. The number of stars contained within these symbols denotes the CATZOC value. For example six stars are given to the highest level of data quality (A1) and two stars to the lowest (D). A single star is not used to avoid possible confusion with a rock symbol. Areas that have not been assessed for CATZOC are shown as the symbol (U) for unassessed.
            • Our Zones of Confidence (ZOC) table outlines the position accuracy, depth accuracy and seafloor coverage for each of these values to help you manage the levels of risk during navigation.
              (https://www.admiralty.co.uk/news/blogs/category-zones-of-confidence)

              (https://www.admiralty.co.uk/AdmiraltyDownloadMedia/Blog/CATZOC%20Table.pdf)

               RASTER Vs VECTOR


              RASTER

              VECTOR
              Format / Type
              Facsimile / Copy of a Paper Chart
              Computer Generated Chart
              Cost / Time for production
              Cheaper & faster
              Costly & Time Consuming
              Interrogation for more info
              Not possible
              Possible
              Customisation
              Not Possible
              Possible
              Seamless Chart
              Not Possible
              Possible
              Rotation (Head-Up)
              Not Possible
              Possible
              Display Generation
              Slow
              Faster
              Scale
              Cannot be Changed
              Can be changed
              Coverage
              Worldwide
              Almost Worldwide
              Adding of Information
              Can only be added
              Can be added and removed
              Alarms
              Many alarms are not possible
              Many options for setting up alarms are available
              Loss of Information
              Can not happen as all information is in single layer
              Can happen, if it happens visual indication is provided
              Memory
              Larger usage of memory
              Comparatively    lesser memory is used
              Zoom Facility
              Available (But only as One continue to zoom in , the pixels become magnified & form small dots, grow to become larger squares & there is a lot of distortion.
              Available
              Storage
              The entire chart is stored as a single layer, information stored cannot be displayed separately
              Information is stored in layers & Hence can be displayed selectively
              Symbols / Colours
              Same as paper charts
              As Per IHO standards also have the option of selecting paper chart symbols.
              Usage Continuation
               An interim measure where ENC’s are not available
              Once worldwide coverage of ENC’s is available paper charts will get phased out.
              During Look Ahead / Review Function
              Other charts will be on a different scale
              All charts will be on the same scale (if auto scale option is switched on)

              CHART SELECTION
               The user has to select the chart that is appropriate for the area of operation & ensure that the chart in use is an ENC or RNC(where ENC coverage is unavailable). 
                He should be well aware of any limitations of the chart.
                  Use of appropriate scale is of vital importance. There are six usage bands of chart scale based on the area of operation.
                  Navigational Purpose
                  (Usage Bands)
                  Name
                  Scale Range
                  1
                  Overview
                  < 1:1499999
                  2
                  General
                  1:350000-1:1499999
                  3
                  Coastal
                  1:90000 – 1:349999
                  4
                  Approach
                  1:22000 – 1: 89999
                  5
                  Harbour
                  1:4000 – 1:21999
                  6
                  Berthing
                  >1:4000
                  •  Each ENC is identified by an 8 character identifier.Identification of ENCs:
                  Eg: FR501050
                  1st 2 characters = THE PRODUCER – (FR-France)
                  3rd Character = Usage Bands  from (1 to 6)
                  Last Five Characters = Alpha-Numeric & Provide a Unique Identifier

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