I'm wondering if the "Florence" ship master realized too late he had much too much way on for the room available and had reversed his engines causing "Flo" 's bow to unintentionally swing to port and prevent the port to port passing. Or steering or engine controls failed to respond when needed.
It looked like the big red ship was quite possibly far enough to its own stbd to potentially have cleared with a normal port to port, and at that point was proceeding with safer close to minimum steerage way.
But the masters are of course the only ones who initially know their sides of the complete story. There could even have been a small vessel or other obstruction on red ship's port side. Passing has to be pretty tricky in best of times with ships that size in the restricted space available, and Too bad for both masters and the ship owners, particularly "Flo" 's. Presumably there was radio communication in addition to sound signals.
But it's a darn good thing they were not dead-on to make that crash much worse for crew and property.