Brutal conditions with waves like "liquid mountain ranges " in the South China Sea have forced Volvo Ocean Race organisers to consider postponing Sunday's launch of Leg 4 at the cost of at least $500,000.
The six-strong fleet is due to set sail from Sanya, the main city of the southern Chinese province of Hainan, for the 5,220-nautical mile trip to Auckland.
However, a boat-breaking weather front heading over the Philippines with forecasts of Cyclone-strength winds churning up waves of over 10 metres looks likely to delay the start until Wednesday.
"This is the toughest, fastest, around-the-world professional race in the world and our sailors are used to taking on treacherous conditions in all weathers," Race CEO Knut Frostad told Reuters.
"But this goes far beyond that. These size waves, they're like liquid mountain ranges, can split a boat in two in a heartbeat."
Organisers would spend the next 48 hours studying weather charts and leave the decision until the last possible moment before the scheduled start at 1400 local time (0600 GMT) on Sunday, he added.
"We're not in the business of cosseting these guys. If it's possible for them to sail, they'll go. But if all shipping heads for cover in the region because of the weather then we'll have to follow suit."
He declined to speculate on how much a delay would cost the race including the teams but insiders said the figure would be at least $500,000 for the organisers and teams.
His stance has split opinion within the fleet and been criticised by Camper/Team New Zealand boss Grant Dalton, who is a former winner of the Race and one of offshore sailing's leading figures.
He wrote to organisers saying: "we should have the guts to get out there".
His skipper Chris Nicholson, whose boat currently lies second in the overall standings, added that the crews should be left to make up their own minds whether to risk the storm.
In the 2008/09 Race, similar conditions forced all but one of the teams to seek refuge sailing out of Qingdao while three boats ended up being smashed.
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