Up-to-the-minute weather data could give Emirates Team New Zealand an upper hand in the America's Cup

Peter Burling's crew is tied one-all with Italian challenger Luna Ross after the first day of racing.

NIWA marine physics scientist Mike Williams says the local team receives information on the direction and speed of the currents and wind, every 20 seconds.

He says they're not breaking the rules as all the information is pre-loaded.

Williams says weather forecasts are just part of the puzzle, as the crew also need to understand what to do with the information.