According to the requirements of the International Convention for the Safety of Life at Sea (SOLAS) 74/88, the AIS system must be mandatory installed on vessels with a gross tonnage of over 300 operating in international waters, vessels with a gross tonnage of over 500 not engaged in international voyages, and all passenger vessels.
These specified vessel categories are also referred to as conventional vessels and must be equipped with Class A AIS equipment. Requirements for such equipment include the presence of a keyboard and display.
Non-conventional vessels (vessels with lower tonnage, recreational yachts, fishing vessels, and several others) often install Class B AIS equipment, which is simpler in design and differs in certain characteristics.
The messages transmitted within the AIS system are divided into three types based on their structure and data transmission intervals:
Static Information - transmitted every 6 minutes.
Maritime Mobile Service Identity (MMSI) number, International Maritime Organization (IMO) number, call sign, vessel name, type, and dimensions.
Dynamic Information - transmitted every 30 seconds to 3 minutes, depending on the vessel's movement, changes in speed, and course.
Coordinates (latitude and longitude), UTC time, navigation status, true heading and course over ground, actual speed, roll and pitch angles, rate of turn, and other radio navigation information.
Voyage Information - transmitted every 6 minutes.
Destination and Estimated Time of Arrival (ETA), vessel draft, cargo class and category, number of people on board, as well as specific messages ensuring transportation safety.
The information recorded and transmitted by AIS is publicly accessible. The system not only helps address safety concerns on waterways but also enables traffic assessment, monitoring of own and other vessels, and order fulfillment control.