Hi Simon -
Agree that the proper course rule doesn't apply - only meant to imply that the F18 should be expecting the F16 to tack, as her course is to the mark. I would hate to be the F18 in that situation, actually, knowing that in the breeze the F16 can probably sail a higher line and I'd need to get past their layline to get to my own, depending upon the distance to the mark. I'm not a short-tacker.
Hmm... wisecracks, anyone?