No personal experience with AISCatcher, but doesn't look like a Phd in Rocket Surgery is required.
On SignalK just need to add a Data Connection, using
NMEA 0183, UDP and no reason not to use the default
NMEA UDP port number of 10110. See attached picture.
From the
AISCatcher web site, under the section titled "Sharing over UDP", looks like all you need is a command similar to
Code:
AIS-catcher -u 127.0.0.1 10110
assuming AISCatcher and SignalK are running on the same box and that the SignalK UDP connection was configured to use port 10110.
If they're running on separate boxes, change the loopback address (aka localhost) to the correct IP address of the SignalK server.