How would you decide this?

Dave Perry’s 100 Best Racing Rules Quizzes highlights specific aspects of the racing rules in a fun format designed to help you become more familiar with The Racing Rules of Sailing. Here is one of the quizzes:

Quiz 43
Boats A, B, and C, all on starboard tack, are approaching a leeward mark to be left to port. When two lengths from the zone, A is clear ahead of B, and C is overlapped with B. When A reaches the zone (position 1), B is overlapped with A and C is still overlapped with B. C rounds the mark inside boat A and B. A protests C.

You are on the protest committee…how would you decide this? Answer below.

Quiz 43 Answer:
Disallow A’s protest. When A reached the zone, the rights and obligations in rule 18.2(a), Giving Mark-Room, depend on whether the boats are “overlapped” at that time. The definition Clear Astern and Clear Ahead; Overlap states: “One boat is clear astern of another when her hull and equipment in normal position are behind a line abeam from the aftermost point of the other boat’s hull and equipment in normal position. The other boat is clear ahead. They overlap when neither is clear astern. However, they also overlap when a boat between them overlaps both.”

Because C was overlapped with B, and B was overlapped with A when A reached the zone, by definition, C was “overlapped” with A. Therefore, A was required to give both B and C mark-room under rule 18.2(a)(1), which she did.

Source: US Sailing