Duncan, yes, I got a little excited reading and then responding about the Fourier Transform. I am getting prepped now for short race to Mexico, this weekend, and will try to post an example afterwards from last week's w/l racing where we had some oscillations going on.  Cheers.

My experience with the Fourier transform is that it converts a time domain function in to the frequency (or period) domain.  For time histories, we normally plot the parameter as a function of period. It  would be interesting to see the shape of a Twd transform funtion this way.  In the above example, for Twd, I assume that whatever Twd is at the time, the transform is then giving the period of that Twd.  I have normallly tried to evaluate Twd oscillations, while racing, by a visual process looking more for the period of change of the Twd, such that I can report up that the Twd oscillation is approx. X degrees with a period of approx. Y minutes to try to help the tactitian get in phase with the shifts.  So to me, it is the period of Twd change, which might be the slope of the transform function.  Thoughts?

Fantastic. Much needed for course change.

Thanks Campbell. Grided sounds like the way I thought Exp has historically done it. Is that correct?

Nick White said on FB that it is on the Weather Settings page and to select Streamlines instead of Barbs.  It looks like you need version 10.0.12 or newer. 10.1 is ready for uploading. I had trouble on my last upgrade with a Windows file that also needed to be upgraded. It  just would not load.