Track ships with AIS in OnAir

Ships broadcast their identity, position, course and speed on two VHF channels near 162 MHz.

What you need#

A radio that tunes 156 to 163 MHz (an RTL-SDR is enough) and a VHF antenna with a view of the water.

Choose AIS (group Maritime). The mode starts near 162 MHz and runs at 2 Msps, which covers both AIS channels (161.975 and 162.025 MHz).
Press Start.
Ships appear on the Map; the other sub-views are Table, Messages, NMEA and Range (the range plot is new in 0.2.6).
Set your position so the range plot and distances work.
Switch on the AIS NMEA data feed (UDP) in View > Data feeds if another program should receive the sentences.

Noise is no longer accepted as ships (fixed in 0.2.5, issue 87).
AIS positions can be shared on map.on-air.dev if you opt in (Server menu). See Privacy.
The related VDES mode listens to the successor system's ASM messages on the same channels.
Ship traffic can include private details in some countries' view. See the legal page.