Electronic Chart Display and Information System
An Electronic Chart Display and Information System (ECDIS) is a computer-based navigation information system that complies with International Maritime Organization (IMO) regulations and can be used in lieu of paper navigation charts. The system displays information from electronic navigational charts (ENCs) 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 primary function of an ECDIS is to contribute to safe navigation. It is required to have at least the same reliability and availability as conventional paper charts. The advantage of an ECDIS over paper charts is reduced labor associated with using and maintaining paper charts and an increased level of situational awareness.
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 type of electronic chart data.
Vector Charts
Vector Charts, or ENC's, are the chart data bases for ECDIS, standardized as to 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 IHO specifications, as contained in Publication S-57.
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) which may be considered necessary for safe navigation and can be displayed 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 Nautical Charts, or RNC's, 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 detail information as it does in ENC. IHO Special Publication S-61 Raster Nautical Chart Product Specification provides guidelines for the production of raster data. IMO resolution MSC.86(70) permits ECDIS equipment to operate in a Raster Chart Display System (RCDS) mode in the absence of ENC.
Regulations
Mandatory Requirements (IMO)
From July 2008, ECDIS will become mandatory on fast passanger vessels. A timetable for the mandatory use of ECDIS on other SOLAS class vessels will be announced at NAV 53 in 2007 - it is anticipated that by 2012 all SOLAS class vessels will have to meet this mandatory requirement. For more information related to this and other important information releated to ECDIS and ENC, visit the Primar RENC service.
ECDIS (as defined by IHO special publications S52 & S57) 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. The performance requirements for ECDIS are defined in by the International Electrotechnical Commission (IEC) in specification 61174 Ed. 2, Maritime navigation and radiocommunication systems - Electronic Chart display and information system (ECDIS) - Operational and performance requirements, methods of testing and required test results.
NOAA however gives the following caveat: Please be aware that the data derived from these extensions are not intended to be used for navigational purposes. The developers of this program - the National Oceanic and Atmospheric Administration, Perot Systems Government Services, and the Environmental Systems Research Institute - assume no responsibility and can not be held liable for any end use of this software. For your own protection, please label all output with "NOT FOR NAVIGATIONAL USE."