Human perception problems of ECDIS electronic chart displays

Human perception problems of ECDIS electronic chart displays

Interesting article about the tendency of mariners to trust ECDIS more than paper charts.

the Dutch cargo vessel Nova Cura . On the 20th of April 2016 the ship hit a reef in the Mytilini Strait in Greece. No casualties were reported, but the ship was total loss. It appeared that the ECDIS (Electronic Chart Display and Information System) indicated a depth of 112m at the grounding location, whereas the actual vessels draft was 5.8

Both the paper chart and ECDIS had the same error;

The linked article suggests that only paper charts be provided in areas with poor surveys.

it can be considered to provide no ECDIS charts at all for areas with known reliability issues. If a ships crew still wants to enter this area, they should be using the traditional paper charts instead. This is a clear sign for the officer to be extra vigilant, and pay attention to additional information sources, like pilot documents.

Similar to this incident:

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This makes no sense at all. Why not mark ALL the various charts in some way to indicate unreliable soundings.
There are ways to depict this on paper charts, surely someone can come up with the electronic version.
(WARNING - depths inside this area are just made up bullshit, we are too cheap to actually survey the area so we stuck some numbers in there to make the boss happy and took a long lunch, enter at own risk)

They are marked.

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If people ignore that and run aground anyway, they were warned.
Anyone have a screen shot of such markings? If you are willing to ignore those warnings, would you not also ignore the same ones on a paper chart?

You may want to review the survey information on that is provided on all charts, as it is quite important.

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Back in day when electronic charting was new some of the Bahamas and other places outside of the 1st world were WAY off their charted positions. The charts dates from 18th century surveys that were pretty accurate relative to an island once you saw one, but the raw lat/lon could be a mile off.
I know of one boat run up a reef because of that and there have been others.
Locally we have shifting channels and sandbars, I can overlay the USACE surveys if there are any and they are color-coded as to age on Aquamap.
I know of some inlets with no charted marks or depths, they usually have a note about local knowledge required, marks constantly being shifted as the channel shifts, etc.
I can’t recall anyplace offhand with normal looking soundings and a note they are not reliable. Old maybe, but not “we did a crap job surveying, who knows what’s really here”. Those places tend to be blank areas with no info IIRC.

In this high tech era it might be good if echo sounder and GPS data was automatically uploaded to some kind of central database for further analysis. Every ship with an echo sounder is effectively performing a crude depth survey with useful data that is lost.

If the echo sounder and GPS data of many vessels was uploaded to a central database it would provide very crude but useful survey data.

The location and depth data could be analysed for anomalies compared to charted depth. Many ships would submit garbage data because of problems with the echo sounder, but algorithms could screen out the garbage data and spot consistent measurements that indicate inaccuracy with the official charted data.

If the data from many ships report much shallower depths than the charted depth, then it could be flagged up as an area of concern for a proper survey to be performed.

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Navionics has been doing this for years. There is a layer of crowd-sourced soundings you can turn on and off.

The research institutes like Woods Hole have extremely high detail soundings of much of the ocean but no place to submit them to as they aren’t “official”.

As yachtsailor pointed out, this has been done for awhile now in the recreational market along with crowd-sourced local knowledge in the form of entities like ActiveCaptain (now owned by Garmin).

The big impediment to doing this in the commercial world is the liability. A purpose-built survey vessel with professional equipment and personnel is a heck of a lot easier to “trust” than any old vessel with equipment dating to who knows when and setup who knows how.

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The two big unknowns are how accurately the depth of the transducer was set and the state of the tide. The tide in some areas can be way off the tables with sustained winds and the transducer depth on a recreational boat may have never been set and on a large ship it obviously changes with loading.


What’s the plan here, we all going to stay home till the world’s oceans are fully surveyed? Navigation in poorly surveyed areas just requires different procedures. It’s SOP in Alaskan waters.

Don’t test the charts, stay on the regular routes. Maintain larger UKC margins than in well surveyed areas. Don’t go poking around in shoal areas without local knowledge.

During voyage planning check the CATZOC / source diagrams. Read the sailing directions / coast pilots.


Sailed up to Instanbul in the 90’s with a new chart, black and white in fathoms, survey was in the 1890’s
Note warned that the Gallipoli peninsula is 5 miles north of where its marked on the chart.
GPS was useless to use to navigate as it put you on the land everywhere.

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