An update, so 100,000 tons comes to a sudden stop from c8 knots, well you can imagine the energy that impacts.
Many moons ago I used to sale across the Channel and you always need to be aware that you had to keep out of their way, it took miles for them to stop, and the ships were a lot smaller then.
I had to go down yesterday morning and the roads were covered in ice/snow/mush. A couple of times I twitched despite going slow, now if you keep it straight with minor adjustments you are ok but otherwise very easy to lose it, seems this is what happened here, they lost their steering with the power outage, let go the anchor but that would cause you to twist, power came back on but by that time it was too late, slammed it in reverse probably that caused the black smoke due to the bunker fuel they use, but it would have taken a long time to bring it to a stop. And you can not effectively steer in reverse.