The test event mimics the format for next year's Olympic regatta.
Tomorrow defending Olympic champions Jo Aleh and Polly Powrie enter the women's 470 medal race lying third.
New Zealand's Games prospects continue to burgeon with the 49erFX crew of Alexandra Maloney and Molly Meech coming fourth.
They haven't finished outside the top 10 at major international regattas this year and contest their world championships off the coast of Buenos Aires in November.
Elsewhere, Gemma Jones and Jason Saunders contest their Nacra 17 medal race tomorrow. They are sixth overall, five points off a top five finish.
Finn sailor Josh Junior will contest the double-points medal race in fifth overall.
Andy Maloney finished 11th in the Laser while Paul Snow-Hansen and Daniel Willcox were 20th in the men's 470; both crews missed their respective top 10 medal races.