AIS for AIS-catcher

Use MQTT unless your setup needs another transport. Add the options starting at -Q, -H, or -u to the command you already run, keeping its input settings and other outputs. Save and restart your existing receiver process; do not start a second process on the same USB device.

Two details that trip people up. The port in the MQTT address is required — AIS-catcher does not assume 443 for wssmqtt://. And MSGFORMAT NMEA_TAG works too, carrying the time each message was received in a TAG block, which is worth it if your station ever buffers.

For the UDP path, your station shows up as a hash of your address, never the address itself, or as your vessel's MMSI once it has sent its own position report. UDP is unauthenticated and therefore the lowest-trust path: those messages appear on the map and in the streams immediately, but they reach the raw feed and other aggregators only while a trusted source has heard the same vessel recently.

Create a token in your browser — no sign-up, no email, and it does not expire.

Then you probably do not want AIS-catcher. It is a decoder: it turns radio into NMEA sentences. A fixed-mount VHF with AIS receive has already done that, and already has the filtering and a real marine antenna, so it hands your computer finished sentences with nothing left to decode.

If the machine it is wired to runs Signal K, use the Signal K plugin instead. It shares every sentence the server receives, needs no extra wiring, and sends network traffic back out to your chartplotter. Running AIS-catcher alongside it would also mean two programs wanting the same serial device, which one of them will lose.

With no Signal K, AIS-catcher can forward from the serial port instead of decoding — AIS-catcher -e 38400 /dev/ttyUSB0 -u udp.ais.openwaters.io 10110. 38400 is the standard rate for AIS on NMEA 0183. Wire the adapter receive-only.

This is the part most people do not know exists. Contributors can read the deduplicated feed — every station, every source, one stream — back into their own AIS-catcher instance, so the viewer stops being a picture of what your antenna hears and becomes a picture of what the network hears.

AIS-catcher's own network inputs are plain TCP and UDP, not WebSockets, so bridge the feed into its built-in UDP server and point its web viewer at the result. Install websocat first. Leave your hardware receiver running, then run these commands in two separate terminals on the same computer:

/v1/nmea needs a token at the contributor tier, which your station earns by feeding — so this is the thing feeding gets you, not a separate product. Each frame is one message, sentences joined by CRLF, with a TAG block naming the station that heard it, the time, and the licence its source publishes under.

The bbox is optional and repeatable, and worth setting even though the load is not the reason. A Pi 5 took the unfiltered world at about 0.2% CPU, so that is not what bites. AIS-catcher's vessel table holds 4,096 ships, and a worldwide feed fills it in minutes and then churns — which means the six-minutely static messages carrying vessel names mostly arrive after a ship has already been evicted, and you get a map of unnamed contacts. Bound it to the water you care about and the names stay.

Keep the network out of your receiver outputs. The viewer command above is a separate instance, with no forwarding outputs and community sharing disabled by -X off. Keep your hardware receiver’s MQTT, HTTP, and UDP outputs on its original process. Adding those outputs to the network viewer would send the aggregate back as your own reception. If you combine inputs in one process, configure output groups so only locally received traffic reaches each sharing output.

Open localhost:8100 to see the network viewer. Keep the bridge and viewer processes running. The example bounding box covers southern British Columbia; replace it with your area’s south, west, north, and east limits in decimal degrees.

Already running Signal K? Then skip the bridge. The Signal K plugin already pulls network traffic in and re-emits it as NMEA 0183, so AIS-catcher can read the server's output directly and show your receiver's own targets and the network's together, with no token and nothing to install:

AIS-catcher -t txt://localhost:10110 -N 8100 -X off

Raw NMEA feed reference

Individual volunteer receptions are dedicated to the public domain under CC0. The combined volunteer database is published under ODbL; partner feeds keep their own terms. You can keep using your receptions and sending them to other networks.

The contributor agreement sets out those terms. Read how the open network works for federation, reuse rights, and the forthcoming bulk archive downloads.

Your station gets a page as soon as it is heard, showing the vessels it has heard, how far it reaches, and how many messages it was the first to deliver. That last number is the one worth watching. A rooftop in a busy harbour can log millions of messages that three other stations also logged; a station on an empty headland can log a fraction of that and be the only reason those vessels appear at all.

Ranking by volume would tell you to point antennas where the ships already are. Heard-first tells you to point them at the gaps, which is the actual problem. Naming your station is optional and free.

Open the live map

Open Waters AIS never asks a station to stop feeding anywhere else, and never will. AIS-catcher fans out to as many destinations as you configure, and docker-shipfeeder supports the Open Waters feed directly. Follow the shipfeeder setup instructions to enable it without adding a second copy of the same output.