Put it this way, if I'm outside and leeward, you're inside and windward, the seas are flat, the breeze is moderate and no one else is around. As soon as you pass the lay line, I'm heading you up to tack. I'll follow the rules and keep clear while turning, but what rules are going to be on your side if you don't respond?
As I said previously, the leeward boat (L) may turn head-to-wind, provided she complies with rules 16.1, 17 and 18.2(b). The windward boat (W) must, in accordance with rule 11, head up to keep clear. If, however, L passes head-to-wind, then she must keep clear and rule 15 does not protect her. W need not turn past head-to-wind.
Mark-room or no mark-room, W is not obligated to tack.
