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AIS and VMS: What is the difference ?

AIS and VMS: What is the difference ?
  • PublishedJuly 31, 2023

In our articles, we often talk about AIS and VMS for ship tracking. But what exactly are these devices?

AIS, a safety device

AIS stands for Automatic Identification System. Its purpose is to transmit a ship’s position to others vessels. It is a safety requirement created in 2002. AIS is mandatory on all vessels over 15 meters.

IMO requires large ships to broadcast their position with AIS in order to avoid collisions. AIS transmits a range of information : position, vessel identity with MMSI, course and speed are all reported.

Ground stations and satellites receive this information. This data is then made available to the public. AIS uses a higher transmission frequency. However, In some cases, the AIS may have to be deactivated for safety reasons. For example, in areas at high risk of maritime piracy, ships deactivate their AIS. This reduces the risk of piracy.

VMS, a monitoring tool

VMS is the acronym for Vessel Monitoring System. It is one of the four worldwide positional data systems to exist. Positional data are used to study fishing effort and its effects on marine habitats.

It was created in 1997 by the European Union to monitor the position of fishing vessel. It is compulsory for fishing vessels over 12 meters in length.

However, under the impetus of the FAO, the VMS was not content with being a European standard. It has become an international system.

Unlike AIS, VMS cannot be tampered with. It is also more difficult to lose data, and is subject to strict confidentiality rules.

AIS and VMS, why choose ?

The combinaison of both could help prevent illegal activities into marine habitats.

Although not the first use, AIS help locate illegal, unreported and unregulated (IUU) fishing.

For instance, the globalfishingwatch website turns “big data into actionable information”. It does this by combining publicly available AIS with information obtained from vessel monitoring systems available through partnerships with governments. Thus, impacted areas can be better monitored, and action taken at sea.

Some fishermen prefer to remove it to escape surveillance. This delays rescue operations in the event of shipwrecks, fires or other incidents. Events whose severity could have been minimized if the AIS had been effective or the VMS present.

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