To significantly improve safety at sea, NOAA has led in the development of electronic nautical charts (ENC) that conform to electronic chart display and information systems (ECDIS). Following a recent notice issued by the International Hydrographic Office, NOAA and other hydrographic offices around the world are examining their ENC suites to uncover potentially serious issues with the display of some soundings on ECDIS. NOAA has also issued a notice to mariners to highlight the issue.

What is the problem?
When mariners use either the “base” or “standard” display in ECDIS, they turn off the soundings. When they use these display modes, navigation systems will not highlight isolated soundings that are shallower than the surrounding depth contours.

As shown above, ECDIS displays the isolated sounding when the display mode is “full.” The mariner can see that isolated shoals are located on the wrong side of the depth contour. ECDIS does not depict the isolated shoals in “standard” and “base” display when the safety contour is set to 3.6 meters, in this example.

What do mariners need to do?
Since the ECDIS does not set off any type of warnings or alarms for these types of soundings in any display mode, it is important that the mariner turn soundings on during route planning and route monitoring to ensure that there are no isolated soundings in the voyage path.

NOAA issues Notice to Mariner
In order to rectify this situation, NOAA is examining its entire ENC suite for these explicit cases. In the meantime, NOAA has issued the following notice to mariner:

NOAA Electronic Navigational Charts – Display of Isolated Shoal Soundings
Mariners are advised that ECDIS may not display some isolated shoal depths when operating in “BASE” or “STANDARD” display mode. Route planning and monitoring alarms for these shoal depths may not always be activated. To ensure safe navigation and to confirm that a planned route is clear of such dangers, mariners should configure the ECDIS to display “ALL DATA” and should visually inspect the planned route. The mariner should not solely rely on the automated voyage planning check function. NOAA is in the process of examining its ENC data for these cases and will issue a notice to mariner for each area that has been examined and updated.

In addition to warning mariners, NOAA will examine and correct the relevant navigational scale ENC’s for the following ports as its first priority, beginning March 8, 2010.

NOAA will examine the rest of the U.S. ENC suite in the coming months, as resources allow.

For more information, please submit comments through our OCS inquiry form.