Pretty much every boat with onboard motors are capable of reversing thrust. Do they all switch like that when traveling in reverse? (Serious question, not a boat person, never been on a boat that wasn't a ferry )
I don’t think boats travel in reverse very often because it’s inefficient to do so. If the boat is going in reverse, it’s probably docking, maneuvering, or having problems. In any of those cases, the crew should be situationally aware enough, and the boat slow enough, that they don’t need color-coded lights to keep themselves from causing a collision.
“Normal” boats only go in reverse when they are maneuvering, never for extended distances and at travel speeds. Unless they’re purpose built they never travel in reverse - rudders are less efficient if going reverse, propellers are as well, and hulls are shaped to reduce drag when going forward.
You’ll basically only see boats going in reverse in harbors or exceptional circumstances. In harbors, speeds are generally low and extra caution is required of all ships. For exceptional circumstances, you’ll have special ways of communicating this - specific lighting patterns, flags, horns to warn others.
