It looks to me that on first seeing Empire approaching on her STARBOARD bow, CSCL initiated a hard turn to PORT, to pass wrong side, but the more manouverable Empire did an even more violent turn to her starboard. If the Ship-plotter moving map can be scaled, Empire cleared CSCL bow by just a length, thus regaining the side of the channel where she should have been to start with, but the lumbering CSCL could not, despite a visible effort, turn back before leaving the channel to port and running aground. It was dark, but I have no idea what visibility was at the time.
Or am I reading too much into the moving map?
Holedriller