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.