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 as an alternative to paper nautical charts. IMO refers to similar systems not meeting the regulations as Electronic Chart Systems (ECS).[1]
An ECDIS system displays the information from electronic navigational charts (ENC) or Digital Nautical Charts (DNC) and integrates position information from the Global Positioning System (GPS) and other navigational sensors, such as radar and automatic identification systems (AIS). It may also display additional navigation-related information, such as Sailing Directions and fathometer.
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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.
There are two types of electronic chart data.
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 IHO Publication S-57.[2]
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 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 Publication S-61 provides guidelines for the production of raster data.[3] IMO Resolution MSC.86(70) permits ECDIS equipment to operate in a Raster Chart Display System (RCDS) mode in the absence of ENC.[4]
ECDIS (as defined by IHO Publications S-52 and S-57)[5] is an approved marine navigational chart and information system, which is accepted as complying with the conventional paper charts required by Regulation V/19 of the 1974 IMO SOLAS Convention.[6] as amended. The performance requirements for ECDIS are defined by IMO and the consequent test standards have been developed by the International Electrotechnical Commission (IEC) in International Standard IEC 61174.[7]
The future standard for ENCs will be defined in IHO Publication S-100.