Facts
Boats A and B were running on starboard tack close to the shore against a strong ebb tide in a Force 3 breeze. A was not more than half a hull length clear ahead of B. B blanketed A, causing A to gybe unintentionally. This was immediately followed by a collision, although without damage or injury, and B protested A under rule 
10. The facts were agreed, and both boats were disqualified: B under rule 
12 because she was too close to A to be keeping clear, and A under rule 
10 for failing to keep clear of a starboard-tack boat.
A appealed on the grounds that she was compelled by B's action to break rule 
10. The protest committee, commenting on the appeal, stated that B caused both A's gybe and the collision by not keeping clear when both boats were on the same tack.
Decision
The boats were passing close to the shoreline, which was an obstruction and also a continuing obstruction. Therefore, the conditions for rule 
19 to apply were met. However, because the boats were not overlapped, neither of the two parts of rule 
19 that place an obligation on a boat (rules 
19.2(b) and 
19.2(c)) applied. When B was clear astern of A she was required by rule 
12 to keep clear but failed to do so. Her breach occurred before the collision, at the moment when A first needed "to take avoiding action" (see the definition 
Keep Clear).
When B collided with A she also broke rule 
14. However, at that time she held right of way under rule 
10, and, because there was no damage or injury, she is exonerated under rule 
43.1(c) for that breach.
After gybing, A became the keep-clear boat under rule 
10, even though she had not intended to gybe. She broke that rule, but only because B's breach of rule 
12 made it impossible for A to keep clear. A did not break rule 
14 because it was not "reasonably possible" for her to avoid contact.
Accordingly, B was properly disqualified by the protest committee under rule 
12. However, A is exonerated under rule 
64.1(a) for breaking rule 
10. A's appeal is upheld, and she is to be reinstated.
GBR 1974/3