Magnetic variation set/read from WMM, calculate TrueWind and ...

[KKempeneers]

Hi,

How do I set magnetic variation in openplotter. GPS RMC sentences return NULL, OpenCPN only outputs those when a route is active. 

Heading True and True Wind are to be calculated ... how do I force Openplotter to calculate those, or are they only calculated when variation is set?

Thanks

Koen.