I was reading a formal accident report a few months back and it was regarding boats... like large boats on the Great Lakes. Over and over again the report kept using the word allision... and I thought it was a typo as I kept seeing the female name Allison.
I then looked up the word allision, and I learned a new term that day.
Yep. Two ships CO-llide because each has a duty to take action to avoid crashing into the other.
Hitting a fixed object is an allision. Bridges and such can’t move so it’s not their fault if a ship hits them. Kind of of like the the joke about the commander of the Navy ship, the punch line of which goes, “This is a light house. Your call.”