The overcast sky and cold winds stirring up waves on Lake Riley didn’t deter the sailors. One boat slid smoothly along a designated path on the Eden Prairie lake. Another hit a yellow buoy along the route. The next zoomed past.

They all gathered, despite the dreary weather on a recent Saturday, to compete in the Solar Boat Regatta, an annual race organized by the Minnesota Renewable Energy Society (MRES) to raise awareness about alternative energy and highlight careers in engineering for middle and high school students. The challenge is to build or adapt a boat to run on solar power, and the reward is that most Minnesotan of summer pastimes — getting out on the lake.

“By racing the solar-powered boats that they built, students experience the thrill of competition and the pride of accomplishment that comes with creating something useful and fun,” said Doug Shoemaker, an MRES board member who retired from Xcel Energy.

The MRES has run the regatta for 26 years, with competition for student teams and adult teams from across the state. Before they launched on race day, they had to learn about solar electricity, wiring, motors, fluid dynamics, boat design, construction and team work.

Over time, the MRES has made a point of reaching out to more diverse contestants and girls, who are underrepresented in science, technology, engineering and math careers. This year’s event included a Sudanese-American crew from a St. Paul church and an 18-member team of Somali students — 11 girls and seven boys — who drove two hours from Rochester STEM Academy.

“We wanted to include diverse teams as we were having almost similar people every year,” said Mark Weber, MRES chairman.

Sagal Yusuf, a junior at Rochester STEM Academy, said solar power was “tricky” in the beginning. She didn’t know much about boating or solar power, but her instructor Bryan Rossi encouraged the students.

“Thanks to Google and Mr. Bryan Rossi, we started enjoying it,” Yusuf said.

Months of preparation

By midmorning on race day, with hundreds of spectators gathered on shore, the announcer sounded the beginning of the first contest — the speed race.

Each boat took its turn navigating from the starting buoy on the right toward the finish on the left. Tanner Novack, a 10th-grader at Glencoe Silver Lake High School drove “The Unsinkable II” to the finish line. “Sea Dragon” from Avalon Charter School in St. Paul followed. Then came Orono Middle School’s “Pink Panther.”

“I was anxious to start the race,” said Novack, wrapped in a towel to ward off the cold, as his teammates welcomed him back to shore.

Not everyone was as lucky. The “Interceptor” boat from Orono High School capsized moments after taking off, prompting a rescue from a lifeguard. (Everyone was OK.)

“We had high hopes on this boat,” said Weber of MRES.

Preparations for the regatta started months ago, with most of the students putting in hours of work after school. Some built a boat from scratch while others modified an existing boat to produce one powered by solar energy.

It costs about $500 for the teams to build a new boat. The cost goes down the next year, however, as teams only have to modify the existing watercraft. Sponsors and regatta organizers help cover the expenses.

The two teams from Orono Middle School started working toward the race in February by building boats with insulation and foam board before connecting them to a battery powered by a solar panel. Technology and engineering teacher Brad Jans coached the two teams as they built the boats and finally tested them once the ice cleared off Long Lake near their school.

“There was camaraderie, disagreements and compromise among the students,” said Jans during a practice session mid-May.

Eighth-grader Isabel Holz­schuh and her seventh-grade teammate Sam Jackson said the after-school exercise was an extension of what Jans taught them in the classes.

“More than the fun of building the boats, we learned how solar power gets converted into electrical energy,” said Jackson, who wants to be a mechanical or chemical engineer — a career choice she settled on after participating in the Solar Boat Regatta for two years.

Racing for the environment

As the regatta continued on Riley Lake, there were slalom races with teams navigating figure eights among the buoys, and finally, the endurance race. Teachers, parents, visitors and the event organizers cheered on shore while the teams took to the water to see how many laps they could make in one hour, switching the boat’s captain every 15 minutes.

There were plenty of antics. Steve Moe, an instructor at Friends School of Minnesota in St. Paul, lifted 7th-grader Cecelia Bauer on his shoulders and waded in the water so that she didn’t waste time getting to the boat when it was her turn as captain. Ahmed Ibrahim from Rochester STEM Academy lost a hat into the lake, thanks to a gust of wind.

“I had borrowed it from my classmate Hashim so I couldn’t afford losing it,” he said.

The teams made 11-24 laps in the designated time. In the end, there was a tie: the Sudanese-American team’s boat “Kandake” and the “Lil Johnny” from Wrenshall High School in northern Minnesota bested all the rest.

But for the participants and the organizers, the occasion is as much about the environment as it is about the competition and engineering exercises.

“It’s cool to learn about how little changes, like using the energy of sun, can affect the environment,” said TJ Demuse, a team member from Academy of Holy Angels in Richfield.

Shoemaker, of the Minnesota Renewable Energy Society, said that message is what matters. The all-volunteer nonprofit, which also does a sustainable home tour each year and runs the Eco Experience at the State Fair, among other things, is celebrating its 40th anniversary this year.

“The larger aim is to make alternative sources mainstream,” Shoemaker said.