It is a flotilla that would have done Dunkirk proud. Hundreds of little ships will be strung out in a floating cordon tomorrow to protect the harbour at Qingdao, the venue for the Olympic sailing events, from an evil invader.

The Chinese authorities were horrified when the showpiece harbour, one of their most expensive Olympic investments, was suddenly filled with algae, turning the blue waters into an unpleasant lime green glue. It took 10,000 workers more than two weeks to clear 100,000 tonnes of slime to get Qingdao ready for the start of the sailing competition tomorrow.

But the Chinese authorities are maintaining their vigilance to ensure that there is no repeat. A two-feet deep net has been strung across the sailing venue and beyond that are hundreds of small fishing boats ready to pounce on any piece of green goo that floats past. Above the cordon of boats, a fleet of helicopters are keeping a constant vigil, watching for any sign of another outbreak of the algae that could disrupt the competition.

“There [are] miles of floating barrier and hundreds of fishing boats out there looking for the first sign of an outbreak,” Morgan Reeser, the coach for the 470 class crew of Saskia Clark and Christina Bassadone, said. “There are helicopters everywhere spotting algae. I counted 217 fishing boats on my own just watching. It is quite an amazing effort to make sure everything is fine for the event.” Algae has become a menace on China’s East Coast in recent years, blooming as a result of climate change, coupled with pollution from industry and farm chemicals. So far, though, it is under control, which is more than the weather is."

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The 18 British sailors in Qingdao are bracing themselves for some of the most difficult conditions in recent Olympic history - not because there could be gales but because the winds might not be strong enough. The typhoons that battered Team GB’s training camp in Macau earlier this week had largely blown out by the time they reached Qingdao, two hours south of Beijing by air.

Cancellations and postponements because the region is becalmed are a possibility, but the team is prepared and ready to spring into action, as Yngling crew showed on Thursday when practice sessions were stopped. Sarah Ayton and Sarah Webb - gunning for their second consecutive Olympic gold medal - plus Pippa Wilson, their new crewmate, beat their 14 rivals into the water as soon as the flags went up for a resumption.

Clark and Bassadone are just as keen and prepared for what lies ahead, whether the wind blows heavens hard or simply sighs. “If you want to moan about the conditions,” Clark said, “don’t be a sailor. We have spent a lot of time getting to learn the conditions and what we face and we have no problems with that.” Bassadone added: “It is just the nature of the sport and we have to be prepared for anything that is thrown at us. We have been in Qingdao a lot and we are getting used to the conditions. It shouldn’t be a problem.”

If any team can overcome the tricky Qingdao combination of big waves and light winds, it is Team GB’s crews. Sailing has been one of Britain’s most successful sports, yielding five medals at each of the past two Olympic Games. Ben Ainslie will be going for his third gold medal in a row in the Finn class to lead a team assault that could yield as many as six medals here in China.

The threat of unusually quiet seas off Qingdao has forced a radical reassessment of technology and tactics, though, as teams search for ways to save weight to make their boats as light as possible to make the best use the wind available. The Clark-Bassadone double-handed dinghy - called a 470 because it is 470 centimetres, or 15ft 5ins, long - has been radically rebuilt to bring its weight down, while North Sails, a British company based in Gosport, has designed specially lightweight and efficient sails for their boat.

Clark and Bassadone hope that will boost their chances of adding to Britain’s already impressive tally of sailing medals written into Olympic history.