At 11:30 a.m. Sunday morning, with New York City under a heat advisory, a gaggle of sailing enthusiasts, dressed in polo shirts and summer dresses, boarded a ferry for Governors Island to watch towering F50 catamarans race along the skyline of Lower Manhattan and in front of the Statue of Liberty.

It was the second day and the finals of the New York Sail Grand Prix, part of SailGP, the growing international sailing competition in which teams, grouped by country, compete in $5 million boats that race up to 60 miles per hour.

The competition was founded in 2018 by Larry Ellison, the tech billionaire, and Russell Coutts, a five-time America’s Cup winner, to build a mainstream sailing league. Unlike America’s Cup, which occurs roughly every four years, SailGP has events around the globe throughout the year, allowing audiences to follow along.

“It’s this high-adrenaline, high-speed sort of racing product right in front of you,” Mr. Coutts said.

Organizers and fans are comparing the competition to Formula 1 racing on the water, which also has billionaire and celebrity backers and flashy backdrops including St. Tropez and Dubai. Now in its fourth season, the number of SailGP teams and events has doubled. The races, filled with Olympic sailors and state-of-the-art catamarans, are broadcast throughout the world and attract millions of viewers, according to organizers.

The sold-out race was held at the tip of Manhattan. Thousands of spectators gathered to watch the race by boat or from Governors Island, a 172-acre island in New York Harbor. (Tickets started at $85 for the grandstand.)

A private tent on a paved area by the water was reserved for team owners and invited ticket holders. There was sushi and dumplings and tea service catered by the Plaza.

The teams were spread around the lounge, marked by flags. Lindsey Vonn, the Olympic ski racer, is on the board of directors for the team from the United States.

“I love speed and adrenaline, so when the opportunity presented itself it was a no-brainer,” Ms. Vonn said in a text message. She attended the race live on Saturday.

On Sunday, the races started around 1 p.m., prompting many guests to put down their champagne and Aperol spritzes and approach the edge of the water to take in the sailing.

Unlike in Formula 1, where a spectator can see only a short stretch of the track at a time, all of SailGP’s racing happens in a tight area in full view of the crowd.

The event is a series of three short races (each one lasts about 15 minutes) in which the boats circle the course multiple times, depending on the wind conditions.

For the boat to turn, 32 functions have to be performed by the team in unison. The catamarans are close enough to shore to see the sailors — there are usually six on each boat — in action.

Jennifer Falvey, 63, a real estate agent, had traveled from Woodstock, Vt., for the event after hearing it about it from a friend. “The boats are just so sexy,” she said.

Daniela Forte, who came with her husband from Westport, Conn., was struck by the speed.

“I don’t have a sailing background, and I had never heard of SailGP before this event, but it’s kind of an amazing idea,” she said. “Sailing has always felt like something you had to do, not just something you can watch, but this is amazing.”

An hour and a half after the first race started, the team from New Zealand was declared the winner (a television broadcaster announced: “The Kiwis have conquered Manhattan.”) The top three contenders are now New Zealand, Australia and Spain — ahead of the season finals in San Francisco in the middle of July.

Then sailors, still wet from the water, filled the lounge for “Apres Sail.” Hundreds of people remained in the private lounge for hours, snacking on fresh plates of pasta and freshly shucked oysters.

Despite the stifling, 90-degree temperatures the party continued until late afternoon. Dance music blared over the loudspeakers, fans mingled with the sailors, and at least one bar ran out of champagne.