I had moment of enlightenment after we had our ECDIS installed but before we figured out how to set it up.
We were leaving Singapore westbound, second mate was on watch, I was in my office doing paperwork while watching using an Ipad running Navionics. We were maneuvering to avoid vessels being overtaken and I noticed the mate was headed for a spot with insufficient under keel clearance (UKC).
On the paper chart that spot was tinted blue but on the ECDIS the same area was white.
I went up to the bridge, showed the mate the shallow spot on the chart and they altered a bit to avoid.
After that the second mate and I figured out at what depths the contours should be and made some how-to on the proper set-up and some step-by-step instructions.