All of a sudden the genoa collapsed. It just fell on the deck and over the rail. We dragged it back on board and examined the head of the sail. It was fine. So with much jiggling and shaking we managed to get the headsail slider down and the shackle was open. But on closer inspection the shackle was bent and could never have been closed. Just as I was about to pull it back up I happened to see a perfectly good identical shackle hanging off the rail. Clearly I failed to replace the shackle when I hoisted the genoa last week.
The breeze lasted a couple of hours and then turned to the south and died. Currently still motoring but the breeze is swinging behind us and slowly filling in.