AIS
Automatic Identification System. A continuous radio broadcast of vessel position, course, speed, identity, and dimensions, mandatory on most yachts above 300 GT.
AIS Class A transponders are mandatory on commercial vessels above 300 GT under SOLAS Chapter V Regulation 19. Class B is voluntary on smaller yachts. AIS data is publicly available through MarineTraffic, VesselFinder, and similar services, which is an operational consideration for owner privacy. Owners can request flagging changes to limit publicly displayed data within the constraints of the regulation.