My buddy works on a boat and I was able to find it and a bit of info about it. Interesting. More things to think of.
Well maybe we know where your Ships are..... AIS is a Marine VHF system with a Maximum TX Power of 25 Watts... typical High Seas range is about 50 miles if the antenna is about 75 ft above the water.... So this means that the Ship MUST be within 50 miles of an AIS Receiver that is linked to the Internet. If not then they do NOT show up on any Internet Site. This system will work well for places like the InterCoastal Waterway, Inside Passage, Great Lakes, Mississippi, Missouri, and Ohio Rivers, and within 50 miles of any Saltwater Port, but will do NOTHING, for ships on the High Seas running farther than 50 miles offshore. .... YMMV....
Yeah, but hijacking a boat 50 or more miles offshore is more difficult. If its just heading out of port or into port it's way easier. And now there is an app for that.