Man, you must not have much body weight. 12 kts with even a G1005 wing is not enough for my foil freak. I weigh in at 200 lb.
More likely is that you are MUCH more efficient than I am....
I'm light weight, but 12 kn avg is not minimal, but the condition that I start thinking, a little more and I'm going for my 3.1 M2 ;), my jumbo sail is foil freek 4.4...
Some folks think 12kts means at some point there was a lull of 12kts.
Other folks think it's 12kts because at some point it gusted 12kts.