Local Argentinian sailors Yago and Klaus Lang have the lead, just one point in front of the Kiwis, while Pavle Kostov and Petar Cupac (Croatia) are one point back in third.
The 49erFX pair of Alexandra Maloney and Molly Meech placed sixth in their race on day two of the world title deciding championship, to move from 20th to 15th overall.
"Tricky day two here at the Worlds in Buenos Aires," says Maloney.
"Lots of waiting on the water for the wind to settle. We managed to get in one stressful light wind race before being sent in. Bring on day three!"
Racing resumes today, and following this the fleets will be split into gold and silver for finals racing.
The medal races are scheduled for Sunday morning (NZT).