Got to the beach a little before noon. There was very little wind in the launch area but promising whitecaps on the far side. By the time I got my 7.5 unrolled, it was apparent that it was going to be too big for the rapidly improving conditions, so on went the 6.6. Excellent session (remarkably steady wind, very few powerboats) for about half an hour. But then --- I had just jibed on the far side and was getting back up to speed on starboard when a white wall appeared directly in my path at very close range. No time to react! Bam!! They came back, asked if I was OK, offered to help, and, to their credit, did not try to blame me for the collision. Meanwhile, I was assessing the damage: Hypersonic even shorter than before, right ankle very sore, but probably not broken. Once I persuaded them to stay downwind of me, I was able to waterstart and sail back to the beach. Take home lesson: you can't be too alert for powerboats because you can't count on them to notice you!