Re: tacking angle
Agree the slower you are going the more leeway, which can offset the theoretically better higher vmg from pointing higher if in fact there were any advantage at a particular point of sale. The gps is showing actual course made so 8 degrees difference is significant.
I think the original thread confused angle to the apparent wind, with tacking angle. One might sail at 30 deg AWA and that is related to the angle of the wind on the sails. There can be a difference in curvature on the luff for different wind speeds so that angle may vary somewhat with windspeed. That is the luff might be tighter in higher wind so you could point higher as the curvature is less. But that depends on sea state you might not tighten it if waves are slowing you and you want more powerinstaed of pointing a bit higher. But then you might have excess power so can point higher. It depends.
But if you are pointing at say 30 AWA your angle to the TWA will vary depending on windstrength as the wind increases the wind effect due to boat speed increases less relative to the true wind. But in a lighter wind the apparent wind may move more ahead so that if you maintain a fixed angle to the AW you are actually sailing at an increased TWA.
Since the windward mark is in the direction from which the true wind is coming in lighter winds you are in fact sailing at a larger angle to the true wind even if sailing by say the windex you are sailing by the AW. You will therefore tack through a greater angle than if the wind were higher.
If the AWA is 30 you are not tacking through 2 x30 but maybe 80 relative to the true wind or even 110 in lighter winds.
In lighter winds therefore although you may keep the same apparent wind angle in fact since the awa moves ahead you are sailng at a greater angle to the true wind as you pick up speed.
I don't know how clear that is as it can be difficult to get one's head around it.