AIS Vessel Traffic

The Automatic Identification System (AIS) is intended to help vessels avoid collision and assist in better control of sea traffic. AIS also provides inter-ship safety information as well ship to shore safety information. The information automatically transmitted by AIS to ships and shore stations includes the vessel's identity, type, position, course, speed and navigational status. AIS provides a "see and be seen" system although there are some AIS units that are "receive only" so other vessels cannot see you which really sidesteps the reason to install AIS. You want to be seen!

An addition to the safety advantages is that a vessel can call any ship over VHF radiotelephone by name, rather than by "ship off my port bow" or some other imprecise identification.

In 2000 the International Maritime Organisation (IMO) made it a requirement for all ships by 31 December 2004 that are of 300 gross tonnes or more engaged in international trade or ships of 500 tonnes engaged in coastal trade to be equipped with AIS.

Now many smaller vessels such as pleasure yachts are AIS equipped not only providing the safety coverage but also family and friends with information of the vessel's current position. One short-coming is partly because the system operates in the VHF marine radio band so has a relatively short transmission range and another is because the spread of shore based stations equipped to receive AIS signals is not evenly spread around coastlines leaving significant gaps in coverage. Coverage is expected to slowly improve over time.

Satellite AIS is available for vessels transiting oceans far from shore based receiving stations. To view these trans-ocean vessels usually requires signing up to a subscription service.

Most yacht clubs conducting offshore races now require competing yachts to be equipped with AIS even if satellite trackers are installed.

Below one can view vessels large and small that have AIS transmitters and that are in range of terrestrial AIS receivers. This site is not a 100% inclusive view but shows most vessels. It is possible to zoom in or out to view different areas.

 This graphic comes from the website marinetraffic.com.