Earlier quoted context omitted.
It's very hard to crack the cargo anyways - it's usually stored in a solid steel 20-to-40 foot shipping container with solid steel lashings bolting everything together. The other plan would be go on board and reprogram the ship to go elsewhere, the nearest deserted coast say, maybe carry the ship's beacons a ways away in a different direction before dumping them in the sea. I'm sure if you crash a whole container shi…
Ships are trackable by satellite. Photos, I mean; they show up on photos. Totally passive. So if you have successfully hijacked a Pacific container ship full of automobiles bound for Los Angeles... where are you going to dock it? Who does the offloading? And where do you sell 5500 sedans at once that makes all this risk worthwhile? I think that planting remotely controlled explosives and extorting payment against sin…
If the transponders are headed to X whilst the ship is headed to Y, it may take you a while before you realise that the ship isn't also headed to X. At which point you now have the problem of determinging which of those fuzzy, cloud-obscured smudges is your ship, and which is someone else's.
Radar can pick up ships, but it also detects, say, rogue shipping containers, of which there are a suprisingly large number.
Existing tracking systems rely on AIS transponders:
http://www.bbc.com/news/science-environment-28372461
Yes, Google can track ships at sea. But it's also relying on AIS, rather than imagery:
http://breakingdefense.com/2012/05/google-satellites-can-tra...
LA-bound cars might be hard. A shipment bound for the Philippines, or India, or elswhere along the Indian or South China seas, quite possibly much easier.