Canyon High School, of Anaheim, looks to defend its title this weekend at the ninth annual Metropolitan Water District Solar Cup boat competition.
The event on Lake Skinner involves 40 Southern California high schools.
The boats are powered by nothing but solar power and the students' ingenuity.
Since November, students have been designing, building and testing their entries.The process started with a boat building workshop.
Contestants' entries were inspected Friday for maneuverability and safety during practice runs.
The competition also involves a technical report and water-conservation presentation that must be presented to judges. It all counts toward a team's final score.
"What also is inspiring is the camaraderie," said Solar Cup coordinator Julie Miller. "Even though high school teams are competing against one another, they will also pitch in to help each other."
The boats are skippered by one team member. Solar-collection panels are deployed as they navigate a one-mile course.
On Sunday, the teams will compete in 200-meter sprint races.
Saturday's competition began at about 8 a.m. The events continues through Sunday.
Since 2002, 7,500 students have taken part in the solar boat races, according to the water agency.