TWS & PPC Errors

Hello,
Your STW (Speed Through Water) is wrong (or you are sailing a rocket). On the screenshot it is 73 Knots. There is something wrong that can impact the calculation of the TWS, TWA, and to compare to the polar (PPC ...). You should have a look at your sensor ...

Hello,
First thing I see is that you have a really big issue with STW (Speed on Water), and actually you are receiving that:
$TIVHW,,T,,M,1273.90,N,2359.26,K*4F

1273.90 kts on water that is really fast

STW instruments shows only the last digits since such a huge number is not at all expected.

Concerning wind we receive
$TIMWV,293.61,R,4.81,M,A*21
which is AWD/AWS (4.81) since it is with "R"

and

$TIMWD,,T,,M,9.31,N,4.79,M*58
which is TWS (4.79 kts). Note that there is no TWD value, and therefore qtVlm is not able to calculate TWA

PPC does not show anything because 1) qtVlm was unable to read or calculate TWA and 2) that would give a too big number anyway.

So the conclusion is that your system sends both AWS and TWS but with the same value, and qtVlm just shows that. There is a big issue with VHW message, and it is also not normal to never receive TWD or TWA
What kind of navigation central is it ?

To be more precise, it is not normal to receive TWS and not TWD or TWA. If TWS/TWA/TWD are all not received, qtVlm will calculate them based on AWA/AWS, but the case where only TWS is present is not covered because that would ignore the TWS received.

Hello and thanks for the analysis. The wind and log values are provided by a Garmin wind bundle 52 which apparently works well since the data on it dedicated displays make sense. Such data are transferred via nmea2000 to a em-trak AIS which is then sending them via high speed nmea0183 to a wifi antenna (yakker) which is in turn sending them via UDP to my pc with Qtvlm.
I don't know what is going wrong. I could understand if all data from the Garmin are somehow not received by qtvlm, but that part of them are wrong....

I would suspect the conversion between NMEA2000 and NMEA0183