OK, OK-I was wrong, but here's one for you!
OK! Obviously those who were out that day know better than I do-the only point I wanted to make is that there are other cues to gauge winspeed in photos.
The "look" of the sails, and heel can give an indication(only a guess, obviously), and FWIW, although whitecaps DO generally appear in the 13-15 range (somewhat less in cold weather of course), and salinity can make a difference as well- a biggie is that when you are looking "downwind" at the water (as in the photo) you are looking at the backsides of the waves, and small whitecaps are harder to see. Put differently, it always "looks" windier when looking "upwind"..
In the winter you will often see whitecaps in 10-11 knots..Remember that in 30*F, 10 knots is a lot more wind than 10 kts is when the temp. is 80* F. You will find that when it is cold you need to reduce sail earlier than when it is warm!! Food for thought, eh?
But of course, "them that was thar" know best what was really going on!
Cheers to all!
Seth