Vessel Automatic Identification Systems (AIS) for Oilfield Operations By Graham P. Cooper, GeoSoft Solutions Manager, Fugro Survey Ltd. On the 1st of July 2004 it was to have become mandatory under IMO/SOLAS regulations for the majority of seagoing vessels of greater than 300 tons to be equipped with an AIS unit when on international passage. A six-month extension has now been granted. An AIS unit is very similar to an aircraft’s transponder and emits dynamic, voyage and vessel related information at regular intervals when underway or at anchor. An AIS unit operates in ship-to-ship mode for collision avoidance; ship-to-shore mode for coastal States to obtain information about a ship and its cargo; and as a tool in vessel traffic schemes for traffic management. The advantage of AIS is that ships can be alerted to the presence of other ships, and coastal authorities can pinpoint the position and identify ships. In its simplest form an AIS unit comprises a GPS antenna and cable, a transponder/control unit and VHF aerial. The system allows messages
to decode, record, analyse and display AIS data to be transmitted automatically between other over a number of different background charts vessels or shore stations equipped with an AIS and drawing formats. AIS is of benefit to the unit. Typically, signals can be received up to a disReproduced by permission of the Controller of Her tance of about twenty Majesty’s Stationery Office and the UK Hydrographic Office. www.ukho.gov.uk nautical miles. The frequency of transmission of dynamic data is dependant upon vessel activity, speed and rate of turn. When certain conditions apply, position data can be transmitted as often as every two seconds from a vessel. GeoSoft Solutions, a division of Fugro Survey Not to be used for navigation Ltd., Aberdeen, has implemented a software pack- Figure 1: Vessel superimposed on a background S57 chart having passed through a age called ChartViewAIS target zone in the Irish Sea. 39