There was no overlap and her spinnaker was flying out of control — how is hitting it my foul?

Because keep clear covers the other boat's hull, crew and equipment — even gear out of its normal position — once it's been out there long enough to be seen and avoided. As the boat clear astern you owe that under Rule 12, and you'd watched that kite flog for minutes. 'It was out of position' won't save you: you broke Rule 12 and Rule 14, while the right-of-way boat is exonerated under Rule 43.1(c). (World Sailing Case 91.)

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