How far can AIS see?

The range of AIS varies depending on several factors, including the transmitter power, antenna height, and the surrounding topography. However, in general, AIS signals can be detected up to 40 nautical miles or around 74 kilometers. This range can be further extended with the use of AIS repeaters, which can relay the AIS signals over longer distances or around obstacles such as hills or tall buildings.

It is essential to note that AIS is not a substitute for other navigation tools, such as radar and visual observation. The system should be used in conjunction with these technologies to ensure the safety of the vessel and its crew. Moreover, AIS should not be relied upon as the sole means of communication, as it is not a dedicated communication channel and can be affected by radio interference or signal blockages.