Yes, AIS shows self-reported positions. Basically it broadcasts your GPS coordinates, your ship's name and other details, plus (unfortunately) any random messa

Yes, AIS shows self-reported positions. Basically it broadcasts your GPS coordinates, your ship's name and other details, plus (unfortunately) any random messages you want to send. Ships have radar too. But my point here is not about sensors--the problem is in the human-computer interface. We can see on the screen that a ship is (or isn't) on a collision course with us, but the systems commonly installed on civilian craft only tell us if another ship is inside our predefined circle. And we have to make that circle fairly small when travelling in busy areas, or there will be alarms at all times. Another fun, dumb thing about AIS: it does not self-report anchor state. It is a requirement that ships display a shape on their bow to indicate if they are anchored. But there is no dissemination of such data in AIS. It would be hugely useful to know the difference between a ship 0.5 NM away at anchor vs underway. And just imagine if we are ourselves in a busy anchorage--we would want an alarm if a ship underway is coming toward us, but not if a ship we are anchored next to is still exactly where we left it. It's not that we don't have sensors to know what we need to know. It's that the displays and audible alerts are not ergonomically advantageous, and are prone to fatiguing their users.