Irish sailor Annalise Murphy has retained the lead in the Laser Radial class but her advantage at the top has been cut to two points.
The Dublin woman, who won the opening four races, finished eighth and 19th at Weymouth on Wednesday.
Matt McGovern and Ryan Seaton are ninth overall in the 49ers after 12th and 19th place finishes.
Bangor's James Espey came in 47th and 42nd in the Laser class and he lies 45th with four races remaining.
Murphy was 12 points clear of her nearest challenger after four races but Belgium's Evi Van Acker closed the gap to just two after Wednesday's two races.
Murphy can discard her worst result after the 10 races are completed.
McGovern, from Bangor, and Carrickfergus man Seaton started the day in sixth and have slipped back after a disappointing two races on Wednesday.
However, they are just 11 points out of the medal positions with another nine races to go.
Ireland's Peter O'Leary and David Burrows are ninth with four races remaining in the Star class.