An Electronic Chart Display and Information System (ECDIS) is a specific form of computer-based navigation information system that complies with International Maritime Organization (IMO) regulations and can be used in lieu of paper navigation charts in some areas. Not all electronic chart systems can be called an ECDIS, and but the term is often incorrectly used to refer to any type of Electronic Chart System (ECS). The true ECDIS system displays information from electronic navigational charts (ENC) and integrates position information from the Global Positioning System (GPS) and other navigational sensors, such as radar, fathometer and automatic identification systems (AIS). It may also display additional navigation-related information, such as Sailing Directions. The ENCs themselves are as important as the system that displays them. Again confusion sometimes exists between official ENCs which HAVE to be produced by or on behalf of an international government Hydrographic Office, and other commercial electronic charts which, whilst they may be able to be displayed on an ECDIS system, do not comply with the IMO regulations for use as the primary navigational chart system. Only when official ENCs are run in a compliant ECDIS system can it be called an ECDIS. All other chart data used immediately downgrades the system to an ECS, and non–compliant, under the terms of the SOLAS regulations for use of Electronic Charts as a primary means of navigation for merchant shipping. This distinction is often over-looked by would be purchasers, but legal beagles may not be quite so ready to ignore the regulations. ECDIS equipment is specified in the IMO ECDIS Performance Standards (IMO Resolution A.817 (19)) 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, 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 by displaying additional navigation-related information if required.
ECDIS is a ship borne navigational device and as such it is the responsibility of IMO. It must support the whole range of navigational functions that make use of the characteristics of the chart data and their specific presentation. Moreover, to be an ECDIS the equipment must be shown to meet all the requirements of the IMO Performance Standards (IMO Resolution A.817(19)) and offer, besides the graphic presentation of chart data, additional information about the characteristics of the displayed features.
Within the ECDIS, the ENC database stores the chart information in the form of geographic objects represented by point, line and area shapes, carrying individual attributes, which make any of these objects unique. Appropriate mechanisms are built into the system to query the data, and then to use the obtained information to perform certain navigational functions (e.g. the anti-grounding surveillance).
The presentation of the current position, range/bearing functions and route planning capabilities are other examples of the minimum ECDIS requirements laid down in the IMO Performance Standards for ECDIS. The presentation of ENCs on the screen is specified in another IHO standard, the “Colours and Symbols Specifications for ECDIS IHO S-52”, i.e. in its Appendix 2, called ”ECDIS Presentation Library”. This style of presentation is mandatory.
The use of ENCs in a tested, approved and certified ECDIS and with appropriate back up arrangements, is the only paperless chart option for vessel navigation.
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Functions
When initially loading an ENC, ECDIS displays the standard display. The standard display uses the system electronic navigational chart (SENC), which is the ENC database together with manual and automated updates. It is this database that ECDIS uses to generate the navigational display. It is equivalent to an up-to-date paper chart. The SENC may also contain additional information from other sources. The level and kinds of information displayed may be modified by the operator subject to the limitations of a display base. The display base is the minimum level of SENC information required at all times in all geographical areas and all circumstances. The display base is not intended to be sufficient for navigation.
Application
ECDIS provides continuous position and navigational safety information. The system generates audible and/or visual alarms when the vessel is in proximity to navigational hazards.
Electronic chart data
There are two types of electronic chart data.
Vector charts
Vector charts are the chart databases for ECDIS, with standardized content, structure and format, issued for use with ECDIS on the authority of government authorized hydrographic offices. ENCs are vector charts that also conform to International Hydrographic Organization (IHO) specifications stated in Special Publication S-57.[1] ENCs contain 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). These supplementary information may be considered necessary for safe navigation and can be displayed together as a seamless chart. ENCs are intelligent, in that systems using them can be programmed to give warning of impending danger in relation to the vessel's position and movement.
Raster charts
Raster navigational charts are raster charts that conform to IHO specifications and are produced by converting paper charts to digital image by scanner. The image is similar to digital camera pictures, which could be zoomed in for more detailed information as it does in ENCs. IHO Special Publication S-61 provides guidelines for the production of raster data.[2] IMO Resolution MSC.86(70) permits ECDIS equipment to operate in a Raster Chart Display System (RCDS) mode in the absence of ENC.[3]
Regulations
ECDIS (as defined by IHO Special Publications S-52 and S-57)[4] is an approved marine navigational chart and information system, which is accepted as complying with the convention paper charts required by Regulation V/20 of the 1974 IMO SOLAS Convention.[5] The performance requirements for ECDIS are defined in by the International Electrotechnical Commission (IEC) in Specification 61174.[6]
References
- ^ S-57 IHO Transfer standard for Digital Hydrographic Data. International Hydrographic Organization. Retrieved on 2007-09-01.
- ^ S-61 Product Specification for RNC. International Hydrographic Organization. Retrieved on 2007-09-01.
- ^ Maritime Safety Committee - 70th session: 7-11 December 1998. International Maritime Organization. Retrieved on 2007-09-01.
- ^ S-52 Specifications for Chart content and display aspects of ECDIS. International Hydrographic Organization. Retrieved on 2007-09-01.
- ^ International Convention for the Safety of Life at Sea (SOLAS), 1974. International Maritime Organization. Retrieved on 2007-09-01.
- ^ 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. International Electrotechnical Commission. Retrieved on 2007-09-01.
See also
| Nautical Portal |
External links
- IMO
- Hydro International — news about hydrography, marine mapping and electronic charting
- ECDIS basics -basics, datum, distribution, organization on board,updating etc.
- ECDIS in operation -colour settings,content settings,own ship presentation etc.
