This usually results in a lee helm that always wants to fall off, so in order to make any way going upwind you always have to steer hard up wind, which further slows your forward progress.
I know I'm being a dog with a bone here and your science is of course good but I just noticed another anomaly.
Leg two that starts at the bottom of the page and goes about NE is amazingly fast. I checked the track details and from 3:51 which is about the start of the turn to 4:11 which puts "8A" abreast the log show speeds of 6,7 and 8 knots. I'm pretty sure I had only the jib up reefed to 100 percent so the only other explanation I can figure is that the current is wicked fast right there like maybe 4 knots, more than double what is predicted.
The other anomaly is that I remember not being able to head up any more than my 50 degrees.
That particular leg really bugs me.
Given the conditions I thought I had I would have predicted a course of about 10 degrees.
What I got was 50 degrees and super fast.
I expect my predictions to be off 5 10 degrees. I'm not good enough at ascertaining the actual conditions to be more accurate than that and in this case I know they changed too.
But to be off 40 degrees hurts. And 8 knots, I was moving but it did not seem that fast.