Advanced Navigator Functions
True Wind Speed Calibration
True Wind Speed calibration assumes that the True Wind Speed upwind reflects the correct value. However, when sailing downwind, airflow over the masthead unit is affected by the spinnaker. Therefore, downwind Tws must be corrected so that your instruments show the same Tws value upwind and down.
The simplest method to achieve this is to measure wind speed upwind and then calculate an average using the wand method. Once the spinnaker is up and the boat is stable downwind, take another wand method reading and average it. The difference between the two values is the correction to be subtracted in the Tws Corrections screen (Figure
