The International Maritime Organizationís (IMO) Sub-Committee on Safety of Navigation (NAV 44) recently approved an amendment to the existing performance standards for ECDIS which will allow ECDIS navigation systems to operate in a Raster Chart Display System (RCDS) mode. The U.S. Delegation, which included representation from NOAAís Office of Coast Survey, played a major role in the success of the measure.

Under the proposal, national maritime administrations may allow vessels the option of using the RCDS mode of operation until the vector Electronic Navigational Chart (ENC) coverage required for the normal mode of operation is available. While operating in the RCDS mode, vessels will be required to use an appropriate folio of paper charts, as determined by the administration.

The action taken at NAV 44 is entirely consistent with NOAAís strategy of producing ENCs for the Nation's 40 largest ports, and expanding coverage thereafter as resources become available. For waters not covered by ENCs initially, NOAA Raster Nautical Charts provide the official electronic chart coverage.

Raster nautical charts already cover much of the world and the concept of ECDIS operating in an RCDS mode is seen as a way of letting mariners maximize the use of the system while ENC coverage expands. This is commonly referred to as the "dual-fuel" mode of operations. The important benefit of the dual-fuel approach is that electronic chart navigation based entirely on official and up-to-date charts is available for almost any voyage.

The option of operating ECDIS equipment in an RCDS mode offers significant safety and environmental protection benefits more rapidly than would otherwise be possible by waiting for the full portfolio of ENCs required to use ECDIS. In addition, the earliest possible introduction of official electronic charting by way of "duel-fuelling" should catalyze shipping companies to invest in ECDIS.

If approved by the IMOís Marine Safety Committee this December, manufacturers will have a set of criteria governing the performance and reliability of ECDIS systems operating in a RCDS mode. Mariners, too, will be assured of the operational reliability of their ECDIS equipment whenever navigating in waters where ENCs are not available.