European champions Chris Draper and Simon Hiscocks are in fourth place overall after Friday's three races in the 49er class.
Although the pair won the day's opening race to move up to third overall, they slipped out of the medals after 13th and 11th places in the other races.
They have a rest day on Saturday before three more races on Sunday.
Meanwhile, Paul Goodison is in fourth in the Laser category after finishing eighth and ninth in the day's races.
Goodison had occupied third place after the first race but was overtaken by Slovenia's Vasilij Zbogar, who finished four places ahead of the Briton in the second race and lies just one point ahead of him.
Goodison's hopes now rest on a good performance in the category's final race on Sunday.
Brazilian Robert Scheidt, the man pipped by Ben Ainslie in Sydney, continues to set the pace in the event on 48 points.
In the windsurfing, Nick Dempsey finished second and ninth in the day's two races in the mistral category and lies in sixth place overall.