I just got a hackrf and it has an AIS tool built in. It's real neat, I've got to play with it a while. It plots them on a map, but it's extremely low res. My city is like 4 pixels. I'd really like to be able to fix that somehow.
I've also noticed a lot of the information it reports seems wrong. Like the same boat can be reporting anchor down and 5 knots. And even more are under way with engine but 0.0 knots. I'm not a boat captain but that doesn't seem right.
It's still endless fun just reading the names of the boats as they pass