HELP!! AWS vs GWS vs TWS

I have the following issue: sometimes my log get stuck due to scale and stuff so the STW values become useless. As backup i have the SOG coming from the GPS. Which are the values related to the True Wind i can look at? I think TWS and TWD are calculated using the STW so they become useless as well? Can i tell qtvlm somehow not to use STW but SOG to do the calculations? Thanks in advance for the support!

Hello
If you have no more Boat Speed, you can use the AWA and AWS as you know, but you can also use the GWA, GWD which are calculated with the apparent wind and the GPS data (SOG, COG). You will get a 'geographic wind' or 'ground wind', better than the 'true' wind. Just check the boxes in the instruments menu.

Mmm what it happens in my case is that the STW is invalid while SOG is valid (see pic attached). The issue is that the TWS happens to be equal to AWS and GWS invalid. I don't know why... 

If your Boat Speed is not valid (considered to 0), it is normal that TWS = AWS
But you should have GWS ...

Exactly, this is my expectation too. Do you have some suggestions how i can make some debugging? Thanks again 

It is a bit hard to understand. Of course if qtVlm does not have HDG/STW/CTW it falls back to COG/SOG instead for calculating TWS/TWD/TWA/etc
Your screenshot does not show AWA. If you don't have that data then obviously there is no way to calculate TWD/TWA, and the best assumption is to say that TWS = AWS.
Can you send us some NMEA log? You can get one either through NMEA setting directly or by showing NMEA rawq data windows and copy/paste in a text file.