Menzies: Thanks for posting the PM analysis. Since reading that, I have looked at the video again, and replayed the first few seconds a few times. I have to agree now with the conclusion that the ferry was not slowing until after the first 5 blasts of her horns, so I must agree with the PM article conclusions.
One surprising note, the Chetzemoka has a capacity of 64 cars. To compare her to an equivalient vessel in the BC ferry fleet, she is smaller than the ferry serving Gabriola Island, the Quinsam, capacity 70 cars, but has 6000 hp to the Quinsam's 2601. I have seen Quinsam in an emergency stop, which it can do effectively, very quickly. From this fact alone, I am surprised the Chetzamoka was unable to avoid this collision.