We are in SF Bay between GG and Alcatraz. Current can be a factor, but we try to account for that. I am measuring total heading difference and dividing by two. So for instance this weekend we were going from a heading of 160 to 270 and then back to 160. We were at slack condition, with winds 20+ mph with some higher gusts.
What I am suspecting is the mast is raked too far aft. When you look up at it, the rake is very significant, I estimate maybe 12 inches.