Clear waters ahead for ECDIS
Regulation 19 of the new SOLAS chapter allows an electronic chart display and information system (ECDIS) to be accepted as meeting the chart carriage requirements of the regulation. The regulation requires all ships, irrespective of size, to carry nautical charts and nautical publications to plan and display the ship’s route for the intended voyage and to plot and monitor positions throughout the voyage. But the ship must also carry back up arrangements if electronic charts are used either fully or partially. Performance standards for electronic charts were adopted in 1995, by resolution A.817(19)), which was amended in 1996 by resolution HSC.64 (67) to reflect back-up arrangements in case of ECDIS failure. Additional amendments were made in 1998 by resolution MSC 86 (70) to permit operation of ECDIS in RCDS mode
Electronic Chart is a generic term used to describe a form of the digital representation of paper chart. An electronic chart can be Raster or Vector chart. They are the next generation of navigational charts.
ENC: An ENC is a presentation of hydrographic and navigational information in digital form.ENC is vector data which is composed of points, lines and features with detailed attributes. They are similar to CAD drawings.From the relationships between these (points, lines and areas) and ship’s features(speed, draft, course) it is possible for an ECDIS system to intelligently detect and alarm the navigator of possible dangerous situations. ENCs are the official vector based ECs designed to meet the relevant chart carriage requirements of SOLAS convention.ENC data can only be issued by, or on authority of, govt. authoorised HOs.Each country is responsible for production of its own ENCs and systematically updating them with all safety- critical information.When displayed with certain parameters and via a type approved ECDIS, ENCs fully satisfy SOLAS chart carriage requirements and thus can be used primary means of navigation.
RNC: RNCs use raster data to reproduce paper charts in an electronic format.Raster representations consist of thousands of tiny clour dots (pixels) that together make a flat digital image.Every pixel is geographically referenced enabling accurate real-time(continually updated) display of vessel position when the chart display system is linked to GPS.Additional user defined information such as route plans and shoal areas can be overlaid on an RNC to provide automatic links to other onboard systems(e.g. warning alarms) but unlike ENCs charted features cannot be selectively displayed or queried.RNC data , itself will not trigger automatic alarms(e.g. anti grounding).However ,some alarms can be generated by the RCDS(RC display system) from user inserted information.These can include: (DISC)
Danger areas, Isolated dangers, Ship safety contour lines and Clearing lines.
ARCS charts are provided on CD-ROM allowing their use in a wide range of equipment, from full integrated bridge systems to stand alone PCs.Worldwide coverage is held on 10 regional CDs and 1 CD for small-scale charts.
ECS and ECDIS: ECS encompasses any electronic system that uses digital chart data.It could be a laptop, PC, PDA or fully integrated IBS. The chart data can be vector or raster. ECDIS is approved type ECS complying with stringent IHO criteria and using official ENC data. IMO requires that:
• ENCs can be used for primary navigation in place of paper charts provided there is a suitable backup( e.g. another ECDIS with a separate power supply, or an appropriate folio of up to date charts.
• RNCs, when used in conjunction with ENCs ( to fill the gaps in coverage) can be used for primary navigation together with appropriate folio of up to date charts.
However this will be up to the Administration to decide what appropriate folio of charts is.
P.S. for ECs were adopted in 1995, which was amended in 1996 to reflect back-up arrangements in case of ECDIS failure.Additional amendments were made in 1998 to permit operation of ECDIS in Raster mode.
In addition to complying with standards of IHO, IMO etc. ECDIS should also meet the specifications laid down by classification society.
Briefly ECDIS must offer following characteristics:
a) Reading ENC data(S57: transfer standard ) and transferring it to SENC
b) Presentation of objects and their characteristics according to presentation library(S52: chart content and display standard)
c) Anti grounding function
d) Warning of obstructions to shipping
e) Updating
f) Various types of chart work must be possible like,entering fixed position,route planning, entering notes and observations,soundings and measuring of distances.
Thus ECDIS does not merely mean presentation of chart in electronic form, it is also an information system.With ECDIS, for the first time, a navigator knows where his ship is and not where his ship was. No single individual invented ECDIS.The currently valid standards have been developed from contributions made by companies, institutions and organizations in many countries.ECDIS offers the same range of features as paper charts and facilitates simpler, faster and above all, more accurate work on the basis of constantly updated data.
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Components of ECDIS: hardware, software and data
Hardware: of ECDIS is generally a computer with graphics capability, a high performance PC or a graphics workstation installed in a console linked with other items of ship’s equipment , like course from gyro, speed from log and ROT from ROTI.Key features are the links with posn sensors of the ship ( decca, loran, etc. ) and in particular with the GPS, supplying via the NMEA interface a constant stream of highly precise posn data(NMEA: national Marine Electronics Association; NMEA0183 Standard for Interfacing Marine Electronic Devices, data record).Even radar pictures can be superimposed, either as raw data from a rasterscan radar or as syntheticARPA.The hardware of an ECDIS must meet the standards of the IEEE ( Institute of Electrical and Electronic Engineers ).
Software: is what makes the computer an ECDIS. It consists of user interface and the so called ECDIS kernel, the software that makes it possible to read the data and display a chart. This software is also called “function library”. Inaddition to the chart picture, the user interface shows buttons and keys for operating the nautical chart.
Data: The official original data (S57 data) of the ENC is usually supplied on CD-ROM or, in case of updates, via digital telephone or satellite communication system.This original data is also called ENC.The chart database is organized incells that cover the entire earth’s surfacewithout overlapping.
The data in the System Electronic Nautical Chart (SENC) is generated from the original of the ENC.The ENC has to be kept unaltered in order to be able to reconstruct the SENC data if this is unintentionally damaged or destroyed.The S57 dta represents a specific kind of attributed vector data.
In addition S57 data should be encapsulated according to the ISO 8211 standard.This guarantees that data from the various national HOs are compatible with one another and can be read by each ECDIS.
S57 however does not contain any information about the symbolization.This standard is given in another IHO publication: S52.It is also called presentation library(PRESLIB)Hence the ECDIS manufacturer must install the presentation library in his unit with the definitions of the symbolization instructions and the colors to be used in an absolute manner irrespective of the color monitor.
Chart data comes without geographic projection, only with coordinates.Ecdis must then provide also geographic projection for a cartographic presenatation.For shipping, it means usually the mercator or sometimes gnomonic projections.
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Correcting electronic charts: Updating is a fundamental requirement for all chart systems.In electronic charts updating can be completed in seconds, in many cases automatically.A useful virtue of electronic updating is that, because official electronic chart databases can contain information from other sources such as Light Lists and Sailing Directions, systems can be arranged so that corrections are made to all relevant references at once.
Full designation ECDIS require that system must be type approved, must display official ENCs issued by national HOs and that they must be kept uptodate.
For full ECDIS compliance the chart database must be updatable automatically or semi-automatically.IHO guidelines indicate that the onboard chart system should be capable of being interfaced with an Inmarsat sitcom station or an EGC SafetyNet-capable receiver for direct transfer of ENC updates.Such equipment combinations can provide fully automatic updating.
For semi-automatic updating the ECDIS should be capable of receiving chart updates in standard IHO format via a telephone network or on 3.5in high density diskettes.This updates must then be fed into the system;s computer.
The above describes the standardization of the data side of ECDIS, or to be precise, of the hydrographic data.There are indeed other chart objects that certainly must be specifiedin order to make ECDIS an adequate navigational tool.A wide range of “objects” are entered into the chart by the captain and the navigators before and during the voyage of the ship.These include leg lines and waypoints, notes, observations, fixed positions and commands.To ensure that this is also possible with the electronic medium of ECDIS, the IMO has developed an ECDIS P.S.This determines how an ECDIS has to work so that it can serve as an adequate replacement for the paper nautical chart.in accordance with the International for SOLAS, 1974. IMOhas produced a catalogue of user-defined objects which has been published under the title “ Mariner’s Navigational Objects” as an appendix to S52.The supplier of ECDIS has to ensure that these objects can be generated, edited and deleted as required. In addition ECDIS should also comply specifications of functionality laid down by classification society.
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ADVANTAGES OF ECDIS OVER PAPER CHARTS: PAWCIP CALDET
Position fixing is real time and is recorded at regular intervals without involvement of OOW.
Alarms can be activated to attract attention of OOW by setting safety parameters whose violation will activate alarms. Can be used as anti- grounding tool.
Weather and forecast data and ice data can be superimposed.
Continuous monitoring of ship’s position wrt planned track and available sea room
When interfaced with ARPA targets acquired by ARPA can also be similarly monitored.
Passage planning can be done on ECDIS itself without referring to various publications as most information available on ECDIS itself.
Charts can be corrected by floppy/ CD
Anchoring can be planned precisely
Log keeping is electronic and easy and voyage playback is possible.
Discrepancy between any two position fixing systems can be easily identified by ECDIS
More accurate ETA can be worked out
With trial manoeuvre being done on ECDIS availability of sea room on new course can easily be checked.
COMPARISON OF VECTOR AND RASTER CHARTS: ccllasssiicc wrrmzd
Customization not possible
Chart appears cluttered
Chart stored in single layer and information cannot be displayed selectively
Since chart is in single layer no possible information can be lost
Alarms of safety depths, TSS etc not possible
Seamless charts not possible
Same symbols and colours as that of paper charts ( symbols clours as per IHO, S 57 )
Scale of chart cannot be changed
Information can only be added
Interrogation for more information is not possible
GPS; RADAR/ARPA information, chart corrections can be overlaid ( Has also same facility )
Cheaper and simple to produce
Worldwide coverage possible
Sensible rotation to any angle like H-up not possible
Display regeneration takes time
Memory requirement is higher
Zooming facility not possible
Direct copy of paper chart. (Computer generated chart)
ERRORS OF ECDIS:
Errors of interpretation or human errors:
Ignoring scale of display ; Uncritical acceptance of own ship’s position; Ignoring difference between True North and Gyro North; Confusion of different type of vectorts, display mode and/or reference system.
Errors of Displayed data:
Source error; An electronic chart can be as good as the source of original data; Object size error; The items on chart are not drawn to scale; Position shift ( due different datums between GPS and chart); reference shift ( a difference in the matching during superimposing of the two displays).
RISK OF OVERRELIANCE ON ECDIS:
ECDIS is only a navigational aid; Limitations of ECDIS and its sensors make over reliance on it dangerous; periodical checks and lookout must be performed and basic principles o watchkeeping observed.
The publishers of official data for the ENCs are the National Hydrographic Offices of the marine nations, as is the case for the paper nautical charts.The IHO committee for ENC database has developed a model for distribution network for ENC services.ThisWorld ENC Database (WEND) model proposes a number of Regional ENC Co-ordinating Centers (RENCs). Each ENC producing nation would send its data to the local RENC that is responsible for storing and distributing chart data and updates to on ship users.
NIMA: National Imagery and Mapping Agency
Topology: study of geometrical properties unaffected by changes in sizes and shapes.
S-57: The official international standard for the programming of software for electronic navigation.
SENC: The database for software manufacturers to display ENC. This is the proprietry internal system format used by the ECDIS and ECS manufacturers for operational use.
ECDIS: It is a complete hardware and software system which conforms to the IMO S-57 requirements. To be called an ECDIS, the system must undergo testing and assessment by authorized IMO representatives.
NOAA: national Oceanic and Administration Administration
Regulation 19 of the new SOLAS chapter allows an electronic chart display and information system (ECDIS) to be accepted as meeting the chart carriage requirements of the regulation. The regulation requires all ships, irrespective of size, to carry nautical charts and nautical publications to plan and display the ship’s route for the intended voyage and to plot and monitor positions throughout the voyage. But the ship must also carry back up arrangements if electronic charts are used either fully or partially. Performance standards for electronic charts were adopted in 1995, by resolution A.817(19)), which was amended in 1996 by resolution HSC.64 (67) to reflect back-up arrangements in case of ECDIS failure. Additional amendments were made in 1998 by resolution MSC 86 (70) to permit operation of ECDIS in RCDS mode
Electronic Chart is a generic term used to describe a form of the digital representation of paper chart. An electronic chart can be Raster or Vector chart. They are the next generation of navigational charts.
ENC: An ENC is a presentation of hydrographic and navigational information in digital form.ENC is vector data which is composed of points, lines and features with detailed attributes. They are similar to CAD drawings.From the relationships between these (points, lines and areas) and ship’s features(speed, draft, course) it is possible for an ECDIS system to intelligently detect and alarm the navigator of possible dangerous situations. ENCs are the official vector based ECs designed to meet the relevant chart carriage requirements of SOLAS convention.ENC data can only be issued by, or on authority of, govt. authoorised HOs.Each country is responsible for production of its own ENCs and systematically updating them with all safety- critical information.When displayed with certain parameters and via a type approved ECDIS, ENCs fully satisfy SOLAS chart carriage requirements and thus can be used primary means of navigation.
RNC: RNCs use raster data to reproduce paper charts in an electronic format.Raster representations consist of thousands of tiny clour dots (pixels) that together make a flat digital image.Every pixel is geographically referenced enabling accurate real-time(continually updated) display of vessel position when the chart display system is linked to GPS.Additional user defined information such as route plans and shoal areas can be overlaid on an RNC to provide automatic links to other onboard systems(e.g. warning alarms) but unlike ENCs charted features cannot be selectively displayed or queried.RNC data , itself will not trigger automatic alarms(e.g. anti grounding).However ,some alarms can be generated by the RCDS(RC display system) from user inserted information.These can include: (DISC)
Danger areas, Isolated dangers, Ship safety contour lines and Clearing lines.
ARCS charts are provided on CD-ROM allowing their use in a wide range of equipment, from full integrated bridge systems to stand alone PCs.Worldwide coverage is held on 10 regional CDs and 1 CD for small-scale charts.
ECS and ECDIS: ECS encompasses any electronic system that uses digital chart data.It could be a laptop, PC, PDA or fully integrated IBS. The chart data can be vector or raster. ECDIS is approved type ECS complying with stringent IHO criteria and using official ENC data. IMO requires that:
• ENCs can be used for primary navigation in place of paper charts provided there is a suitable backup( e.g. another ECDIS with a separate power supply, or an appropriate folio of up to date charts.
• RNCs, when used in conjunction with ENCs ( to fill the gaps in coverage) can be used for primary navigation together with appropriate folio of up to date charts.
However this will be up to the Administration to decide what appropriate folio of charts is.
P.S. for ECs were adopted in 1995, which was amended in 1996 to reflect back-up arrangements in case of ECDIS failure.Additional amendments were made in 1998 to permit operation of ECDIS in Raster mode.
In addition to complying with standards of IHO, IMO etc. ECDIS should also meet the specifications laid down by classification society.
Briefly ECDIS must offer following characteristics:
a) Reading ENC data(S57: transfer standard ) and transferring it to SENC
b) Presentation of objects and their characteristics according to presentation library(S52: chart content and display standard)
c) Anti grounding function
d) Warning of obstructions to shipping
e) Updating
f) Various types of chart work must be possible like,entering fixed position,route planning, entering notes and observations,soundings and measuring of distances.
Thus ECDIS does not merely mean presentation of chart in electronic form, it is also an information system.With ECDIS, for the first time, a navigator knows where his ship is and not where his ship was. No single individual invented ECDIS.The currently valid standards have been developed from contributions made by companies, institutions and organizations in many countries.ECDIS offers the same range of features as paper charts and facilitates simpler, faster and above all, more accurate work on the basis of constantly updated data.
------------------------------------------------------------------------------------------------------------
Components of ECDIS: hardware, software and data
Hardware: of ECDIS is generally a computer with graphics capability, a high performance PC or a graphics workstation installed in a console linked with other items of ship’s equipment , like course from gyro, speed from log and ROT from ROTI.Key features are the links with posn sensors of the ship ( decca, loran, etc. ) and in particular with the GPS, supplying via the NMEA interface a constant stream of highly precise posn data(NMEA: national Marine Electronics Association; NMEA0183 Standard for Interfacing Marine Electronic Devices, data record).Even radar pictures can be superimposed, either as raw data from a rasterscan radar or as syntheticARPA.The hardware of an ECDIS must meet the standards of the IEEE ( Institute of Electrical and Electronic Engineers ).
Software: is what makes the computer an ECDIS. It consists of user interface and the so called ECDIS kernel, the software that makes it possible to read the data and display a chart. This software is also called “function library”. Inaddition to the chart picture, the user interface shows buttons and keys for operating the nautical chart.
Data: The official original data (S57 data) of the ENC is usually supplied on CD-ROM or, in case of updates, via digital telephone or satellite communication system.This original data is also called ENC.The chart database is organized incells that cover the entire earth’s surfacewithout overlapping.
The data in the System Electronic Nautical Chart (SENC) is generated from the original of the ENC.The ENC has to be kept unaltered in order to be able to reconstruct the SENC data if this is unintentionally damaged or destroyed.The S57 dta represents a specific kind of attributed vector data.
In addition S57 data should be encapsulated according to the ISO 8211 standard.This guarantees that data from the various national HOs are compatible with one another and can be read by each ECDIS.
S57 however does not contain any information about the symbolization.This standard is given in another IHO publication: S52.It is also called presentation library(PRESLIB)Hence the ECDIS manufacturer must install the presentation library in his unit with the definitions of the symbolization instructions and the colors to be used in an absolute manner irrespective of the color monitor.
Chart data comes without geographic projection, only with coordinates.Ecdis must then provide also geographic projection for a cartographic presenatation.For shipping, it means usually the mercator or sometimes gnomonic projections.
------------------------------------------------------------------------------------------------------------
Correcting electronic charts: Updating is a fundamental requirement for all chart systems.In electronic charts updating can be completed in seconds, in many cases automatically.A useful virtue of electronic updating is that, because official electronic chart databases can contain information from other sources such as Light Lists and Sailing Directions, systems can be arranged so that corrections are made to all relevant references at once.
Full designation ECDIS require that system must be type approved, must display official ENCs issued by national HOs and that they must be kept uptodate.
For full ECDIS compliance the chart database must be updatable automatically or semi-automatically.IHO guidelines indicate that the onboard chart system should be capable of being interfaced with an Inmarsat sitcom station or an EGC SafetyNet-capable receiver for direct transfer of ENC updates.Such equipment combinations can provide fully automatic updating.
For semi-automatic updating the ECDIS should be capable of receiving chart updates in standard IHO format via a telephone network or on 3.5in high density diskettes.This updates must then be fed into the system;s computer.
The above describes the standardization of the data side of ECDIS, or to be precise, of the hydrographic data.There are indeed other chart objects that certainly must be specifiedin order to make ECDIS an adequate navigational tool.A wide range of “objects” are entered into the chart by the captain and the navigators before and during the voyage of the ship.These include leg lines and waypoints, notes, observations, fixed positions and commands.To ensure that this is also possible with the electronic medium of ECDIS, the IMO has developed an ECDIS P.S.This determines how an ECDIS has to work so that it can serve as an adequate replacement for the paper nautical chart.in accordance with the International for SOLAS, 1974. IMOhas produced a catalogue of user-defined objects which has been published under the title “ Mariner’s Navigational Objects” as an appendix to S52.The supplier of ECDIS has to ensure that these objects can be generated, edited and deleted as required. In addition ECDIS should also comply specifications of functionality laid down by classification society.
------------------------------------------------------------------------------------------------------------
ADVANTAGES OF ECDIS OVER PAPER CHARTS: PAWCIP CALDET
Position fixing is real time and is recorded at regular intervals without involvement of OOW.
Alarms can be activated to attract attention of OOW by setting safety parameters whose violation will activate alarms. Can be used as anti- grounding tool.
Weather and forecast data and ice data can be superimposed.
Continuous monitoring of ship’s position wrt planned track and available sea room
When interfaced with ARPA targets acquired by ARPA can also be similarly monitored.
Passage planning can be done on ECDIS itself without referring to various publications as most information available on ECDIS itself.
Charts can be corrected by floppy/ CD
Anchoring can be planned precisely
Log keeping is electronic and easy and voyage playback is possible.
Discrepancy between any two position fixing systems can be easily identified by ECDIS
More accurate ETA can be worked out
With trial manoeuvre being done on ECDIS availability of sea room on new course can easily be checked.
COMPARISON OF VECTOR AND RASTER CHARTS: ccllasssiicc wrrmzd
Customization not possible
Chart appears cluttered
Chart stored in single layer and information cannot be displayed selectively
Since chart is in single layer no possible information can be lost
Alarms of safety depths, TSS etc not possible
Seamless charts not possible
Same symbols and colours as that of paper charts ( symbols clours as per IHO, S 57 )
Scale of chart cannot be changed
Information can only be added
Interrogation for more information is not possible
GPS; RADAR/ARPA information, chart corrections can be overlaid ( Has also same facility )
Cheaper and simple to produce
Worldwide coverage possible
Sensible rotation to any angle like H-up not possible
Display regeneration takes time
Memory requirement is higher
Zooming facility not possible
Direct copy of paper chart. (Computer generated chart)
ERRORS OF ECDIS:
Errors of interpretation or human errors:
Ignoring scale of display ; Uncritical acceptance of own ship’s position; Ignoring difference between True North and Gyro North; Confusion of different type of vectorts, display mode and/or reference system.
Errors of Displayed data:
Source error; An electronic chart can be as good as the source of original data; Object size error; The items on chart are not drawn to scale; Position shift ( due different datums between GPS and chart); reference shift ( a difference in the matching during superimposing of the two displays).
RISK OF OVERRELIANCE ON ECDIS:
ECDIS is only a navigational aid; Limitations of ECDIS and its sensors make over reliance on it dangerous; periodical checks and lookout must be performed and basic principles o watchkeeping observed.
The publishers of official data for the ENCs are the National Hydrographic Offices of the marine nations, as is the case for the paper nautical charts.The IHO committee for ENC database has developed a model for distribution network for ENC services.ThisWorld ENC Database (WEND) model proposes a number of Regional ENC Co-ordinating Centers (RENCs). Each ENC producing nation would send its data to the local RENC that is responsible for storing and distributing chart data and updates to on ship users.
NIMA: National Imagery and Mapping Agency
Topology: study of geometrical properties unaffected by changes in sizes and shapes.
S-57: The official international standard for the programming of software for electronic navigation.
SENC: The database for software manufacturers to display ENC. This is the proprietry internal system format used by the ECDIS and ECS manufacturers for operational use.
ECDIS: It is a complete hardware and software system which conforms to the IMO S-57 requirements. To be called an ECDIS, the system must undergo testing and assessment by authorized IMO representatives.
NOAA: national Oceanic and Administration Administration
7 comments:
A very good brief on the ECDIS. Thanks
Thanks for the compliment.
Good familiarisation on ECDIS.. Will help me in my Ecdis course starting tomorrow. Thanks Sir..
Very good indeed and many thanks for sharing. I will share the knowledge with my students. Thanks bro.
GOOD and brife detail abut ecdis sir ,will help in my orals exams sir
,could u plz provide some information on anchor handlling
ty very much sir as many of my doubts are clear n your xplanation wil help me in my exams.....
Why ecdis is called anti grounding tool?
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