Two PHRF fleets in the same event were racing on different courses that used the same government buoy as a rounding mark. For one fleet it was a windward mark, to be left to port. For the other fleet it was a leeward mark, also to be left to port. Two boats in the first fleet approached the mark close-hauled on starboard tack, with Silhouette, a Beneteau 40.7, overlapped to leeward and about one half of a hull length behind CC Rider. Air Boss, a J/105 sailing in the other fleet, approached the mark on a broad reach, also on starboard tack. When Air Boss was about one hull length from the mark, she gybed onto port and luffed to round the mark. As she luffed, her bow made contact with the port side of Silhouette, causing damage. At the time of contact, Silhouette was going about 5.5 knots, and Air Boss about 3.5. Silhouette and Air Boss protested each other.

The protest committee decided that rule 18 applied, and that when Air Boss reached the zone, Silhouette and Air Boss were overlapped, since neither was clear astern of the other. It decided that at that time Silhouette was the leeward boat, and that rule 11 applied, requiring Air Boss to keep clear. It also decided that Silhouette was the inside boat with respect to the mark, and therefore Air Boss was required by rule 18.2(b) to give mark-room.

The protest committee also decided that since rule 18 applied, the gybe by Air Boss did not break the overlap, rule 18.2(b) continued to apply, rule 11 no longer applied, and rule 10 began to apply. The committee further decided that as Air Boss began to luff, she failed to give mark room and to keep clear of Silhouette, breaking rules 10 and 18.2(b). Since it was reasonably possible for Air Boss to avoid the contact and she failed to do so, she also broke rule 14. When it became clear that Air Boss was not going to keep clear, Silhouette was unable to change course to avoid the contact, because of the presence of CC Rider to windward. Therefore Silhouette did not break rule 14. Air Boss was disqualified, and appealed.

At position 1, Air Boss reached the zone and rule 18 began to apply (see rule 18.1). At that time, Silhouette and Air Boss were overlapped.

The first sentence of rule 18.2(b) concerns situations in which boats are overlapped when approaching a mark. However, in order for that sentence to create rights and obligations between two boats, there must be both an “inside” and an “outside” boat. An “inside” boat refers to the one rounding or passing “between” the other boat and the mark. At position 1 on the diagram, neither Air Boss nor Silhouette can be identified as the inside or the outside boat in the sense that one of them is (or is about to be) “between” the other boat and the mark. If the courses of the boats were projected straight ahead, neither boat would pass between the mark and the other boat. Alternatively, if the courses were projected to show the boats sailing around the mark, each boat’s course would pass between the mark and the other boat’s course. Neither of these methods identifies an “inside” or “outside” boat.

In these circumstances, no part of rule 18 creates any obligations, and therefore rule 10 applies. Beginning at position 4 in the protest diagram, Air Boss was on port tack, and was required to keep clear of Silhouette, on starboard tack. In colliding with Silhouette, Air Boss broke both rules 10 and 14, and is disqualified. As determined by the protest committee, Silhouette did not break rule 14, since it was not reasonably possible for her to avoid the contact in the very short interval of time after it became clear that Air Boss would not pass astern of Silhouette.

The appeal by Air Boss is denied, and the decision of the protest committee is corrected as explained above.

April 2007