I found one recorded Nmea
file in OpenCPN
File Thingie NMEA
folder that does work with "Polar" plugin
the name of that file is not surprizingly "Konni-Wind-AIS.txt"
This file works with
Source: "GPS" Mode: "Data from Nmea" and playing VDR "Konni-Wind-AIS.txt" having the NMEA Debug Window checked to be sure there is data running.
Then the polars are filled in.
This file also works with
Source: "GPS" Mode: "Data from VDR" and selecting "Konni-Wind-AIS.txt" directly
and a window pops up "Loading Nmea messages from file" Then the polars are filled in quite quickly.
PLEASE NOTE that "Data from VDR" should be called "Data from file" because VDR is not involved.
I think that the Hartmut file should work, because it works fine with the Windows Polar Program called "Polauto" so I think that the Polar plugin is not using all nmea statements that can be available or something.