AIS Live vessel tracking service is a commercial, not cheap, but probably the most comprehensive AIS resource. The AISLive site stated that in their database are approximately 170 thousand ships. Since 2004, the monthly number of recorded AIS positions increased from 600,000 to 8 million.
AIS Live user interface is not very friendly. Zone areas are fixed and people can not roam freely over the map. They stated that you can send e-mail with a request for additional zones.
You can not filter vessels by type. There are no filters at all. Alert notification is not configurable, you can only specify the type of the notification – html or plain, and that’s all.
In resume AIS Live is the biggest AIS network and the first commercial AIS vessel tracking service (started in 2004) but with the most unfriendly and poor user interface of a vessel tracking system.