Boats A and B approached the leeward mark with spinnakers set. A rounds the mark clear ahead of B. A has difficulty lowering her spinnaker and, as she assumes a close-hauled course, her spinnaker guy trails astern by some 30 feet (9 m) and drags across part of the mark above the water. Later, when the mark is about five lengths astern of B, the boats are sailing close-hauled on port tack and B is 20 feet (6 m) astern of A. A is still having difficulties handling her spinnaker and the head of her spinnaker unexpectedly streams astern and strikes B's headstay.

What rules apply during these incidents and does any boat break a rule?

When A's spinnaker guy drags across the mark, she breaks rule 31. A boat touches a mark within the meaning of rule 31 when any part of her hull, crew or equipment comes in contact with the mark. The fact that her equipment touches the mark because she has manoeuvring or sail-handling difficulties does not excuse her breach of the rule.

When contact occurs later between the two boats, rule 18 no longer applies. Because A's spinnaker is not in its normal position, the boats are not overlapped and, therefore, rule 12 applies. That rule requires B to keep clear of A, which she is doing because nothing B did or failed to do required A "to take avoiding action" (see the definition Keep Clear). This is shown by the fact that the contact between them results exclusively from A's equipment moving unexpectedly out of normal position. Therefore, B did not break rule 12.

Rule 14 also applied. A broke rule 14 by causing contact that she could have avoided. However, because there was no damage or injury, A is exonerated (see rule 14(b)). It was not reasonably possible for B to avoid contact with A's spinnaker as it streamed astern, and so B did not break rule 14.

Note that Case 91 also addresses an incident involving equipment out of its normal position.