Tested OpenCPN polar diagram plug-in in my Raspberry Pi. Worked like a charm, here is a small test run in light wind with genua 3 and the main. Wind speed is in knots, but can easily be converted to m/s by dividing by 2.
When you select data source to be Data from NMEA you can concentrate on sailing, since everything happens automagically. Info could be useful after few days sailing with different sail setups.
Plug-in was very easy to install and activate. Just installed it and activated it in OpenCPN.