Use to be able to do a dynamic calibration with earlier Vector SW versions by spinning backwards 8 times. I did this coming out of transition. This was removed by Garmin for some reason. Now I am in the same situation as is everyone who uses vectors for racing. That being all calibrations are done between 5-530 AM. Not sure if the vectors along with computer are doing any temp corrections. I looked at the Garmin forums and seems the recommendation is to re calibrate throughout the day for best accuracy....requires unclipping feet. Obviously not a option race day unless your in the penalty tent.