Red has fouled Blue. As she tacks, Red is subject to rule 13. After that, Red is subject to rule 11 and must keep clear, which she does not do. Blue establishes an inside overlap from clear astern after Red passes head to wind inside the zone and is subject to rule 17 and is entitled to mark-room in accordance with rule 18.3(b). She may sail her proper course but not above it. The collision occurs because Red does not give mark-room. Therefore Red also breaks rule 18.3(b) and rule 11.