As a small vessel (10 metres) owner and operator, it's quite nice that AIS operates over VHF. I can install an AIS receiver and see precisely what's coming my way, and the instrumentation available to me can predict whether I might collide with the ship, or if I'll pass ahead/behind (I prefer behind). Useful in the dark when distance is hard to gauge.

Saw on twitter the other day that one vessel going past the east coast of Africa had changed their info field (destination I think) to "ARMED GUARD ONBOARD"..