Great Britain's sailors remained on course to fulfil their target of four medals at the Olympic regatta in the expected fickle conditions on Qingdao's Fushan Bay. After four races over the first two days of competition, Sarah Ayton, Sarah Webb, the defending champions, and Pippa Wilson, the bow-person making her debut at these Games, lead the Yngling class and Stevie Morrison and Ben Rhodes, world champions last year, are on top of their 49er Skiff class after three races yesterday.

Ben Ainslie, the two-times Olympic gold medal-winner and outstanding favourite in the Finn class, described yesterday as a “unique challenge” to his Olympic experience. He has found the strong tidal currents and the light, unsettled breezes just as tough to decipher as any of the 25 competitors he is up against in the fleet and lies second, five points behind Zach Railey, the light-wind specialist from the United States. A tenth and a first place from Saturday's first two races represent Ainslie's best start to his four Olympic regattas.

In sunshine more reminiscent of the Mediterranean than this corner of China's Yellow Sea, the light and changing winds make the tidal currents the biggest factor in any decision-making, but the Finn racing in particular has often been incredibly close.

Were they not a possible threat to his medal prospects, Ainslie, who won both pre-Olympic test regattas here in 2006 and 2007, might take it as a compliment that his rivals are resorting to forcing a rules infringement on him this early in the regatta. After a marginal incident at the second windward turn of the first race yesterday, he fought shy of taking on Railey in front of a jury, choosing to make a pre-emptive penalty turn rather than risk the kind of unexpected disqualification on the first day of the opening race in 2004 that made winning his Athens gold medal such an epic uphill battle.

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Belt-and-braces conservatism prevailed again in the subsequent contest, in which he decided to sail extra distance and lose places while manoeuvring round a mêlée of boats rather than attract the chance of disqualification. Showing his exceptional downwind speed in a rapidly fading breeze, he still made up seven places on the final run to secure his second victory.

“I am probably going a little bit cautious rather than risk getting into any trouble.” Ainslie said. “It is difficult because in my position, I just want to stay out of trouble and it almost forces you to be too cautious. But that is the nature of this, as I have learnt in the past, that you just have to keep your nose clean.

“In the heat it is hard. It is boiling hot and with the fleet all coming back together, like they did in the last race, just trying to make the right decisions is pretty difficult. It is a unique challenge that we have been facing up to here for the last couple of years. You just look at the mark roundings and someone can be first at one mark and almost last at the next one. You don't see that very often in racing, but that is the game here.”

The return of small clumps of weed, which were such a huge problem during the training period, are also starting to be a concern. Patience has been the key to success so far for the Britain trio in the Yngling keelboat. They lead by five points after four races and Britain's 49er pair of Morrison and Rhodes lead by one point after three races.