My Garmin system only gives me the apparent wind!
So I installed the dérived-data plugin but how to activate True Wind Direction and True Wind Angle under Wind section? Nothing has changed the plugin!

Thanks

1. Having true wind in Signal K. This will depend on a few things, your instruments might already be putting it out into NMEA, if so, it should automatically propagate to Signal K. You can see this in Signal K data browser as environment.wind.directionTrue. If your instruments don't automatically provide it, then you can use derived-data plugin. Install the plugin and toggle on True Wind Direction and True Wind Angle under Wind section. Note that these will require navigation.headingTrue among other things. Check if you have that available, if not you can calculate it from navigation.headingMagnetic but it will require a heading sensor (likely an autopilot) and navigation.magneticVariation, which derived-data can provide.

2. Regardless of the source, once you have environment.wind.directionTrue in Signal K, you can then add a custom monitoring section in Saillogger to monitor it. Details of it is covered in this tutorial.

Good luck!

I'm trying to have the real wind and true wind direction data but I don't know how to do it!!!

I installed the derived data plugin but after?.

Thank you for your help

For true wind speed and direction, you should toggle the following option on in the derived-data plugin:

• True Wind Angle, Direction and Speed

In order to calculate true wind values, the following are required:

• navigation.headingTrue
• navigation.speedThroughWater
• environment.wind.speedApparent
• environment.wind.angleApparent

speedThroughWater should be coming from your speedometer, and when anchored, it will be zero, so no problems there. speedApparent and angleApparent come through wind instrument and should be fine too.

headingTrue is the tricky one, it normally comes through the heading sensor which is normally linked to autopilot but depending on your instruments, it may be sourced from elsewhere too. If you don't have all of these, derived-data will not be able to calculate the true wind readings.

You can see which ones are available in the data browser.

Good luck and happy Saillogging!