Recently, a round was preparing to break down in Singapore EOPL. Due to the need to check the obstacles on the seabed to avoid damaging the cable and other facilities, the second officer found that the ENC planned to be anchored at different scales when displaying electronic charts, the displayed information is very different.

As shown in the figure above, the scale of the area is gradually enlarged. During this process, we found that the sunken ships and cables that were originally displayed in the small scale disappeared after 1:70000. If the scale is enlarged blindly, and the ship anchors where there are cables or shipwrecks, huge losses will result.

So what is the cause of this problem? Through observation and comparison, the author found that the main reason is that the priority of ECDIS when presenting ENC and the accuracy of ENC data cause the above phenomenon to occur.

Let's take a look at the situation displayed on the ECDIS screen when the scale is 1:80000:

At this time, the MY3C0625 picture is displayed on the ECDIS screen. When the scale is 1:70000, at this time, due to the priority order displayed by ECDIS, two pictures are displayed on the screen, the upper part is ID300430, and the lower part is MS3IK2EB. As a result, at the boundary between the two pictures (blue line), there is a clear phenomenon of information discontinuity.