(Reuters) - SoftBank Team Japan earned a surprise bonus on Saturday when the 'Windy City' did not live up to its famed moniker on the opening day of the Chicago stop for the America's Cup World Series (ACWS).

With winds too light and unstable for racing to start on time on the fresh water of Lake Michigan in the six-team event spread over two days, officials decided to take the substitute race from Friday to count on the leaderboard.

That race was won by SoftBank Team Japan, and gave the team a measure of justice as they had also won the substitute race at the previous stop in New York, although that result did not score officially.

"It's a shame we couldn't get racing started on time today, but it's nice to turn the good work from Friday into a win on the scoreboard today," SoftBank Team Japan skipper Dean Barker said after he and his crew earned their first ACWS victory.

"We've been working hard to improve our performance ... Friday was a good day and we take a lot of confidence from that."

Sweden's entry Artemis Racing finished second, Groupama Team France placed third and Emirates Team New Zealand fourth in Friday's substitute race while Oracle Team USA came in last after their sailboat capsized.

The 45-foot twin-hulled sailboats, known as AC45Fs, rise up on retractable hydrofoil keels and rudders and create the appearance of flying over the surface of the water.

Weather conditions eventually improved on a steamy afternoon in Chicago on Saturday and a substitute race for Sunday was held off the eastern tip of the city's iconic Navy Pier.

Emirates Team New Zealand, the series leaders, finished ahead of Oracle Team USA and Artemis Racing in that substitute race, which will score as official should the wind again not be suitable for racing on Sunday.

However, "excellent" conditions have been forecast for the final day of the Chicago stop in the qualifying series for the 2017 America's Cup in Bermuda.

Races in the ACWS have already been held in Portsmouth, England, Gothenburg, Sweden, Bermuda, Oman and New York, and will move to Toulon, France and Fukuoka, Japan.

The boat designs will be scaled up to 50 feet for the America's Cup in Bermuda, which is set to begin in May 2017 and climax with the final two teams vying for the oldest trophy in sport, known as the "Auld Mug."

The America's Cup race has been held every few years since 1851, except for pauses during the world wars.

(Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Andrew Both)