Both Starboard, reciprocal course & who is windward when?

Q: I'm going downwind, by the lee on starboard gybe. Wind is about 5 knots. There is another boat which has already rounded the leeward mark, coming upwind towards me on starboard tack. We hold our courses, with him on a bearing to pass to my port side, and me to pass on his port side. We're on more or less reciprocal bearings. As we pass, my boom hits his mast. There is no damage. We both protest. Who is wrong?

A: This has always been a bit of a conundrum. If you take the situation a few boat lengths back, the running boat was probably on the windward side of the boat close-hauled, so the running boat is the keep-clear boat. When she crosses the line projecting ahead of the close-hauled boat she ceases being the keep-clear boat and so might possibly be said to ?acquire right-of-way?, requiring her to initially gives room to the other boat (rule 15).

But if you just take the situation you describe, and if both boats are sailing steady courses, then both boats are on starboard tack and both are on the other boat?s leeward side, so neither is windward boat, and rule 11 doesn?t apply. The only rule that can be applied is rule 14 requiring each to avoid contact with the other and if there is damage, both boats could be penalized.