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Signal K servers

Signal K is an open standard for boat data: a server on the boat reads every instrument it can reach and streams the values in one format.

A Signal K server is a second way in, beside a NMEA gateway. A boat can have both, and Lookout reads both at once.

Adding a server​

Open the gear (⌘, or Ctrl+,), choose Connections, then Add Server. Servers keep their own list under Signal K servers, below the gateways.

The Signal K servers list, under the gateways, in the Connections section on macOS

  • Name. What you call this server. Leave it empty and the row shows the address instead.
  • Address. The server's name or IP address on the boat's network.
  • Port. Most servers stream on port 8375.
  • WebSocket. It starts off, which reads the plain stream. On reads the WebSocket stream instead, which the reference server serves on port 3000.
  • On. The switch at the right of the row.

Port 3000 is the server's own web page. If you type the address into a browser and the server's dashboard comes up, that is port 3000, and it is not the plain stream. Use 8375 with WebSocket off, or 3000 with WebSocket on.

A row reports its state the same way a gateway's does: Connected with a rate, Reconnecting, Unreachable, Paused or No address. The rate counts deltas a second. A delta is one update from the server, which may carry several values.

How a Signal K server differs from a gateway​

A gateway repeats one instrument network, sentence by sentence, and whatever is not on that network is not in the stream. A server collects from everything it can reach, NMEA 0183 and NMEA 2000 and anything else it has a driver for, and sends the boat as one named set of values.

What Lookout takes out of that stream is the same short list either way: your position, heading, course and speed, the depth, the wind, and the AIS traffic. A server carrying tank levels, engine temperatures and battery state is sending them, and Lookout does not read them yet.

Working out why nothing draws​

The row says Unreachable. The address is wrong, the server is not running, or you have the plain stream's port with WebSocket on, or the web page's port with it off.

The row says Connected · N deltas/s, own ship not named. The stream is arriving, and it never said which vessel is yours. Your boat will not draw, though the AIS traffic around it will. Fix it in the server: it is the server's own vessel identity that is missing, not anything you type here.

The row says Connected and nothing draws at all. The server has reached no instruments. Its own dashboard, on port 3000, lists what it is receiving.