One of the best website for ship tracking information is marine traffic. With a quick research on Google we can find different alternatives: vesseltracker, shipfinder.com, shipfinder.co, lloydsintelligencelist.
The technology that these websites use to track vessels information is called AIS (Automatic Identification System). Following some information from Wikipedia.
AIS is an automatic tracking system used on ships and by vessel traffic services (VTS) for identifying and locating vessels by electronically exchanging data with other nearby ships, AIS base stations, and satellites. When satellites are used to detect AIS signatures then the term Satellite-AIS (S-AIS) is used. AIS information supplements marine radar, which continues to be the primary method of collision avoidance for water transport.
AIS transponders automatically broadcast information, such as their position, speed, and navigational status, at regular intervals via a VHF transmitter built into the transponder. The information originates from the ship’s navigational sensors, typically its global navigation satellite system (GNSS) receiver and gyrocompass. The signals are received by AIS transponders fitted on other ships or on land based systems, such as VTS systems. The received information can be displayed on a screen or chart plotter, showing the other vessels’ positions in much the same manner as a radar display. The AIS standard comprises several substandards called “types” that specify individual product types: Class A (Vessel-mounted AIS transceiver (transmit and receive) which operates using self-organised time-division multiple-access (SOTDMA) ), Class B (Vessel-mounted AIS transceiver (transmit and receive) which operates using either carrier-sense time-division multiple-access (CSTDMA)or SOTDMA), Base Station (Shore-based AIS transceiver (transmit and receive) which operates using SOTDMA), Aids to Navigation (AtoN – Shore- or buoy-based transceiver (transmit and receive) which operates using fixed-access time-division multiple-access (FATDMA)), Search And Rescue Transponder (SART) (Specialist AIS device created as an emergency distress beacon which operates using pre-announce time-division multiple-access (PATDMA), or sometimes called a “modified SOTDMA”), Specialist AIS Transponders.
AIS receivers are not specified in the AIS standards, because they do not transmit. The main threat to the integrity of any AIS system are non-compliant AIS transmissions, hence careful specifications of all transmitting AIS devices. The International Maritime Organization‘s International Convention for the Safety of Life at Sea requires AIS to be fitted aboard international voyaging ships with gross tonnage (GT) of 300 or more tons, and all passenger ships regardless of size.
Shipboard AIS transponders have a horizontal range that is highly variable, but typically only up to about 74 kilometres (46 mi). They reach much further vertically – up to the 400 km orbit of the International Space Station (ISS).
Some of the people behind the companies that are using AIS to map ship positions meet recently at the AIS-Summit event in Hamburg.
Do you know other interesting ship tracking systems?