I'm doing some analysis of a race we did in October and have some questions about the target and polar metrics output to the Expedition log file.  The first leg of our race was downwind and we were sailing to optimize VMG.  When Analyzing the log files, I noticed the following, which I'm hoping someone can explain to me:

1. VMG was always output to the log files as a negative number whereas VMC was output as positive.  Why would VMG be negative. We were definitely heading toward the mark and had the next mark selected in the routing window, so this can't mean we were heading in the wrong direction.

2. Target TWA was always output to the log as a positive number no matter which tack we were on.  This may be a function of the polar file in that there is only one polar for both tacks. Could I fix this by having a PolP and a PolS where the TWAs in PolP are negative? When comparing the the actual TWA, should I just take the absolute value of the actual TWA to compare how far off of the target TWA we were?

3. When sailing VMC, I understand we should be using the Polar BSP, Polar TWS, etc. I hadn't selected to output these to the log file (which was unfortunate) but I have now set them to output in the log settings.  There doesn't seem to be a value to output for polar TWA, though.  Have a missed a setting?