Sharing Watchkeeping Information using AIS Application Specific Message

As an application of the ASM (Application Specific Message) of AIS (Automatic Identification System), which is so called “binary message”, The author developed a system which shares information of the targets tracked by ARPA (Automatic Rader Plotting Aid) with other ships and boats equipped with AIS receivers. The system transmits two types of position data; one is absolute positions and the other is relative positions to the tracker. In 2013, for both data types, the accuracy of the tracked positions was evaluated at Tateyama comparing with the global positioning system (GPS) data of a boat under tracking, and this paper reports the result.