SOUTH PORTLAND — Tanner Nussinow wasn’t overly optimistic about his chances of paddling his cardboard pirate ship to victory, but that did little to dampen his spirits.

The Casco Bay High School junior, decked out in a sailor hat and pirate eyepatch, stood on Willard Beach just after noon Friday as crowds of spectators gathered along the water’s edge. Next to him was the pirate ship he and classmates from the Portland high school had crafted using cardboard, tape and paint. A mermaid graced the bow, her tail wrapped artfully around the side of the little brown ship.

“It’s not going to float, absolutely not,” Nussinow said as his crewmates waved cardboard swords, hoisted a treasure chest in the air and got themselves hyped up for the race.

Friday marked the 11th year that Casco Bay High School students trekked across the bridge to South Portland to race cardboard boats at Willard Beach. The grand prize is bragging rights.

As the school year draws to a close, each crew – or advisory team – at the expeditionary learning school designs and builds a boat. Each boat carries two paddlers who try to navigate about 50 yards into the water, around a teacher in a kayak and back to shore.

This year, 21 cardboard boats built by students – plus one designed and raced by teachers – were carried onto the beach as parents, alumni and beachgoers cheered.

Everyone was ready to race.

Brooke Teller, a chemistry teacher, said the races showcase not just boat-building skills, but the creativity, teamwork and camaraderie the school fosters. It’s also a chance for students to show off their competitive side at a school that doesn’t have sports teams, she said.

“It’s really a big community event,” Teller said. “It shows the joy of our school.”

Anna Hall, a 17-year-old junior, helped her crew craft the Titanic, a wide boat designed to allow a rower’s legs to dangle in the water.

“By the time you get to junior year, you build the boat the way you feel,” she said of the Titanic, whose ultimate fate was similar to its namesake.

“We wanted to go for silly,” chimed in her crewmate, Devon Case. “We’re going for giggles.”

After students lined up the boats in the sand, paddlers were outfitted with life jackets. The first three races were for individual grade levels, with the winner of each heat moving on to the final championship race.

During the freshman heat, several boats broke into pieces the second they hit the water. The Leque Crew boat cut quickly through the water and made it back to shore first, though it was sitting noticeably lower in the water by the time two paddlers scrambled back to the sand.

“It was cold, but it was a lot of fun,” paddler Anna Power of the Leque Crew said as she dragged the boat up to dry land. “We didn’t think it would make it, but it was exciting.”

By the time the junior heat began, Jasper Sommer, a crewmate of Nussinow and the second paddler in the pirate ship, was ready to race.

“I’m going to get pretty wet,” he said. “Hopefully I make it back to shore.”

Sommer did make it back to shore, but not before the pirate ship sank. Nussinow and Sommer waved their cardboard swords in the air victoriously as pieces of cardboard floated around them and their classmates raced ahead of them in the water.

In the championship heat, the canoe-shaped boat built by teachers finished ahead of the students, but it was the Bernstein Crew of sophomores who were declared the winners. Students cheered and hugged, then picked up the soggy remnants of their ship and headed to the buses for the short ride back to school.

“It’s a last day of school all the kids want to be at,” said Teller, the chemistry teacher. “It’s a great way to send the kids off into summer.”