What Happened??

At the beginning of the second upwind leg of Race 2, Oracle trailed New Zealand by over 500 meters. In the light air they seemed to be on the right side of all the shifts and closed the gap. A poor tack by the Kiwis let Oracle round the right gate mark on New Zealand's transom. But when both boats gybed together on Leg 6, Oracle fell off the foils and confusion seemed to reign on board.

In this ACTV video footage, it's hard to see who's doing what in the aerial and onboard shots, but if you look closely you can see...

• While on port gybe, Tom Slingsby leads Kyle Langford to the starboard hull to prepare the gybe. Langford then grinds while Slingsby is on the helm. The wing has not yet gybed. The sheet is slack on starboard, and trimmed on port.
• Number 1 Graham Spence is seen on his knees on the trampoline on the port side. He starts to cross, in front of the wing, hesitates, and takes a step back towards the port hull. In the next aerial shot you can see him cross in front of the wing, to the starboard hull.
• Number 2 Kinley Fowler starts to step out of his cockpit on the port hull, then steps back.
• Helmsman Jimmy Spithill is not in view. Normally he would be holding the wing sheet. I assume he releases the port wing sheet and we see the wing gybe. It's not clear why the wing gybes since there is no tension on the starboard wing sheet. Did Oracle have hydraulics to tack and gybe the wing?
• Spithill crosses to the starboard hull.
• Slingsby crosses back to the port hull, apparently to grind at pedestal 1.
• Fowler is grinding on pedestal 2 in the port hull.
• Number 3 Cooper Dressler is not grinding; he seems to be sitting at the wing trimmer's position, looking up at the wing.
• In the starboard hull we see Spence, Langford and Spithill. Spence turns the handles a few times, stops and seems to be waiting for something. The onboard mics pick up someone (Slingsby?) saying, "Pressure's coming back." Spence says something including the words "oil build."

What was going on? Did they lose hydraulic pressure during the gybe? Their accumulators should have been fully charged - they had made their last tack, to starboard some time earlier, well before rounding the mark and bearing away. Had they bled off all their pressure with the board rake controls when they tried to engage New Zealand after the Kiwis tacked? It's a bit mysterious! It was certainly disastrous - the Kiwis won the race easily and put their first point on the scoreboard.