Shades of ECDIS
When Performance standards were made, they addressed minimum requirements. Some of these requirements were minimal (e.g. screen size, standard display), other were quite elaborate (e.g. Alarms and indications, route planning and monitoring).
The manufactures went ahead and started competing which each other with respect to add-ons over and above the performance standard. Similar to a phone or a car manufacturer who would give you more features for the same price. This included making the safety depth alarmable, display of shallow and deep contours.
There are very relevant arguments on how these add-ons will provide more information to the user. More information meant more awareness and was supposed to lead to incident free navigation.
I am not a fan of many such add-ons and feel the navigator should be exercise caution in using the same, he/she should not be swayed by all the reasons given unless he/she is convinced.
One such add-on is using 4 shades (Shallow contour / Safety Contour / Deep contour) instead of a simpler 2 shades (only Safety contour) with a limiting danger line. Below is what the performance standards state (MSC 232)
There is no mention of Shallow or deep contour. Also, many a times they become meaning less due to availability of depth contours on an ENC. Normally a shallow contour is equal to draft or chosen a contour lower than the safety contour. No navigator should be interested in this contour as he/she really doesn’t want to come near to it or rather breach it.
Deep contour is supposed to give an indication that the vessel could be subjected to pronounced squat as the Deep contour figure is chosen as twice the draft. Here again sometimes due to availability of the contours the safety and the deep contour merge rendering the deep contour useless.
Below is the display requirement of ECDIS for reference
But the real issue comes when we to switch on 4 shades at night and then sometimes the screen becomes so unfriendly. If you add traffic and other navigational over layerdon it, the ECDIS screen starts looking like a puzzle where your trying to locate your ship, track and course.
Below figures will reveal what I am trying to convey
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2 shades day ???
???2 shades night??????????????????????????????????????????????????????
?????4 shades day ????????????????????????????????????????????????????????????????????????????
?4 shades night
2 shades is always clutter free and easier to navigate on, at night as well the clarity is not lost. For safety of navigation we can use the LDL (LDL must be used on 4 shades too as the shallow or deep contour are not alarmable anyways).
But in order to provide more info even the safety management system procedures have adopted 4 shades. In providing all the information we do not look at COGNITIVE OVERLOAD it can cause to the navigator.
How many times we have heard after an incident that – THE INFORMATION WAS RIGHT THERE IN FRONT OF THE NAVIGATOR BUT HE/SHE DIDN’T SEE.
We should understand if we can do two things successfully on ECDIS, we would have better situational awareness – DISPLAY OPTIMISATION and ALARM OPTIMISATION. A cluttered ECDIS screen is not going to help. 4 shades is not helping.
Assistant Vice President at Tata Projects || L&T || AMET University|| Indian Navy
3 年This is typically known continuous evolution of a process or system either to incorporate new technologies or incorporate changed user requirement over a periodic time . ECDIS SORs were promulgated by IMO ?? I opined that a feedback can be given to make ECDIS to meet true user requirements , Add Ons should be available for customisation .
Master Mariner, MRM Facilitator and Consultant
3 年It is upto the user to remain well informed at all times.
Master Mariner
3 年If the user is adequately trained, I believe that 4-shaded display has a lot of advantage. However, as an easy reference, the 2-shaded display does make it simple. In a 2-shaded display, the blue area could be used as a de-facto 'no go' area.
Culture I Organisation Development | Diversity & Inclusion
3 年Well said!
Founder and Director at eTrACKS
3 年Yes at times there is more information than required. Ecdis has many advantages over paper charts. But a few disadvantages as well. A navigator will have to devote more attention in training and understanding an Ecdis compared to a paper chart to be able to use it more effectively. In Ecdis Safety contour is one of more contentious topic. An entire chapter can be dedicated to it. 2 shades n 4 shades both have their benefits, when properly used.