On Sunday, July 14, 2013 2:08:50 PM UTC-4, jfitch wrote:
Got a question: the Butterfly wind vector and the XCSoar wind vector (derived from Butterfly information) seem to disagree by 180 degrees. That is they point toward each other. XCSoar seems to believe it too, based on glide calculations.

Could you please confirm that you are saying that when XCSoar uses wind data from Butterfly Vario that it calculates glide based on the exact opposite of the correct wind vector? If so, that is a rather serious defect and you should report it to XCSoar.org pronto.