I got this working on my build of 5.2
in the bc.ini file I set the following to make a udp output
NMEA_ComPort=""
NMEA_UDPAddress="localhost"
NMEA_UDPPort="10110"
you could use the ip address of anthoer computer if you were running your chartplotter on another one.
10110 is what NMAE strings are sent on by convention, however as long as they match on opencpn and bc.ini and are not used by other things they should work
On opencpn
Options (spanner or cog symbol) -> Connections -> Add Connection
Properties network
Protocol UDP
Address 127.0.0.1 (or whatever computer you are running bc on)
DataPort 10110
Priority 1
tick control checksum
tick receive input on this port
untick output on this port
Apply
tick enable in the list (possibly disable other sources)
OK