Middle Harbour Yacht Club commodore Martin Hill said he spoke to a crew member who told him Shockwave V overshot the island, which acts as a turnaround marker for the yachts to head
back to Sydney
The yacht, entered in the night race under the name of PriceWaterhouseCoopers, was rounding the islet when it experienced a "Chinese gybe", Mr Hill said.
A Chinese gybe, also known as a death roll, happens when a yacht is sailing dead downwind in windy conditions, and suddenly starts to roll back and forth with increasing amplitude.
It reaches a point where the boat actually broaches to windward and is also turning sharply to leeward causing it to gybe uncontrolled, or crash gybe.
"You go around that rock yourself and you know it well and you just know that there must have been a terrible set of circumstances that created this tragedy," Mr Hill told AAP.
"The original report says the keel
fell off but my understanding is that the boat did this Chinese gybe."
timesonline.co.uk and au.news.yahoo.com.