ECDIS

DEFINITION

—  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/20 of the 1974 SOLAS Convention, by displaying selected information from a system electronic navigational chart (SENC) with positional information from navigation sensors to assist the mariner in route planning and route monitoring, and if required display additional navigation-related information.

PERFORMANCE STANDARD:

—  ECDIS should be capable of displaying all chart information necessary for safe and efficient navigation originated by, and distributed on the authority of, government authorized hydrographic offices.

—   ECDIS should facilitate simple and reliable updating of the electronic navigational chart.

ECDIS should reduce the navigational workload compared to using the paper chart.

—      It should enable the mariner to execute in a convenient and timely manner all route planning, route monitoring and positioning currently performed on paper charts.

—   It should be capable of continuously plotting the ship's position.

—   ECDIS should have at least the same reliability and availability of presentation as the paper chart published by government authorized hydrographic offices.

—  ECDIS should provide appropriate alarms or indications with respect to the information displayed or malfunction of the equipment

—  ECDIS should be capable of displaying all SENC information.

—  SENC information available for display during route planning and route monitoring

—  should be subdivided into the following three categories, Display Base, Standard Display

—  and All Other Information (see Appendix 2).

—  ECDIS should present the Standard Display at any time by a single operator action.

—   When a chart is first displayed on ECDIS, it should provide the Standard Display at the largest scale available in the SENC for the displayed area.

—   It should be easy to add or remove information from the ECDIS display. It should not be possible to remove information contained in the Display Base.

—  It should be possible for the mariner to select a safety contour from the depth contours provided by the SENC. ECDIS should emphasize the safety contour over other contours on the display.

—   It should be possible for the mariner to select a safety depth. ECDIS should emphasize soundings equal to or less than the safety depth whenever spot soundings are selected for display.

—  The ENC and all updates to it should be displayed without any degradation of their information content.

—   ECDIS should provide a method to ensure that the ENC and all updates to it have been correctly loaded into the SENC.

—   The ENC data and updates to it should be clearly distinguishable from other displayed information, such as, for example, that listed in Appendix 3.

—  It should not be possible to alter the contents of the ENC.

—   Updates should be stored separately from the ENC.

—   ECDIS should be capable of accepting official updates to the ENC data provided in conformity with IHO standards. These updates should be automatically applied to the SENC. By whatever means updates are received, the implementation procedure should not interfere with the display in use.

—  ECDIS should also be capable of accepting updates to the ENC data entered manually with simple means for verification prior to the final acceptance of the data. They would be distinguishable on the display from ENC information and its official updates and not affect display legibility.

—  ECDIS should keep a record of updates including time of application to the SENC.

—   ECDIS should allow the mariner to display updates in order to review their contents and to ascertain that they have been included in the SENC.

Advantage of  ECDIS over paper Chart:

—  Position fixing can be done at required interval without manual interference

—  Continuous  monitoring of the ships position

—  When interfaced with ARPA/RADAR,target can be monitored continuously

—  If two position fixing system are available,the discrepancy in two systems can be identified

—  Charts can be corrected with help of CD/online

—  Passage planning can be done on ECDIS without referring to other publications 

—  Various alarm can be set on ECDIS

—  Progress of the passage can be monitored in more disciplined manner ,since other navigational data is available on ECDIS

—  Various alarm can be activated to draw the attention of OOW

—  More accurate ETA can be calculated

—  Anchoring can be planned more precisely

ELECTRONIC CHART SYSTEM IS OF TWO TYPES

—  Electronic Navigational Charts (ENCs) and

—  Raster Navigational Charts (RNCs).

—  Electronic Navigational Charts (ENCs) are official vector charts that conform to strict IHO Specifications that have been issued by or on behalf of a national hydrographic authority.

—  ENCs consist of digitised data that records all the relevant chart features such as coastlines, buoys, lights, etc. These features and their attributes (such as position,colour, shape) are held in a database -like structure that allows them to be selectively displayed and queried, creating the potential to manipulate the chart image when displayed on screen. Because of their  vector format, ENCs can also be linked to other onboard systems to provide additional automatic features such as warning alarms.

—  3 variations of the same ENC, showing minimum, intermediate and maximum data display levels.

RNC

—  RNCs use raster data to reproduce paper charts in an electronic format. Their familiar ‘paper chart’ image helps users gain confidence with the use of electronic charts, by providing a direct link between display screen and chart table. RNCs consist of thousands of tiny coloured 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 your 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