HERNANDO BEACH — The one-person, single-propeller submarine is called Sublime. The two-person one is named Subzero. Both were built by Hernando County students, who recently raced them — with great success — in the biennial International Human-Powered Submarine Races.The competition took place at the Naval Surface Warfare Center's Carderock Division in Bethesda, Md., about 15 miles north of Washington, D.C. It was sponsored by the Navy and General Dynamics Electric Boat Division and organized by the Foundation for Underwater Research and Education.The event is open to anyone, but most of the participants are university and high school students, explained Steve Barton, 68, who, with his wife, Pat Barton, 68, advises the Hernando County team and has been doing so for many years.The subs competed in 2013 and came away with first place awards for speed. This year, Sublime's final run was recorded at 6.44 knots, which beat the students' goal of breaking 6 knots. That put the one-man sub in second place overall and first place in the high school division. The winning sub, from the Netherlands, clocked in at 7.42 knots.Subzero, the two-man sub, posted a final speed of 3.97 knots, putting it in second place overall and first place in the high school division. A sub from Canada took first place.Sixteen sophomores, juniors, seniors and recent graduates from Springstead and Central high schools, along with one University of Florida student, were on the Hernando team. Under the Bartons' guidance, the students built their submarines from scratch."It's basically like a bicycle," said Kylie Van Meter, 19, the university student majoring in aerospace and mechanical engineering, describing the submarines' power source. In Sublime, the one-person, four-blade propeller sub, she explained, the pilot lies facedown inside, feet locked with brackets to the bicycle pedals installed near the back of the submersible. To steer, she said, "We have a joystick in the front which works up and down and left and right."These are "wet" submarines, meaning the students breathe using scuba gear, and all participants must be scuba certified.Subzero, the two-person, six-blade propeller sub, is made with the pedals in the middle of the machine. The pilot is facedown in the front and works one pedal and the joystick. The rear person is faceup and works the other pedal. Speed, Kylie said, depends on the strength of the pedal pumping and steering ability.The David Taylor Model Basin at the naval facility is the site of the races. It is a series of basins the Navy uses to test seafaring vehicles and prototypes.The students' submarines were launched by their four-member support team. Two students supported the sub; a third was positioned a short distance from the sub to visually advise the supporting students how to level it; and the fourth surfaced to signal the sub's readiness to launch. The support team pushed it off, and the pilot took over.The competition also included a presentation component. The team produced a PowerPoint presentation and a written report that included information on safety, how the machines were built and what the students learned.The Hernando students have been working on the submarines for two years, including testing in the Gulf of Mexico. "We build, rebuild, build and rebuild," Steve Barton said."I've actually been working on this team since ninth grade," said junior Raleigh Forbell, 16. "I plan to major in engineering. My brother was part of this club, and I looked forward to it."Raleigh is one of the pilots and also a support diver.Junior Wyatt Van Meter, 16, followed sister Kylie onto the team. "She started doing it, and I got to go to one of the practices and see what they were doing, and I got interested," he said.This year's competitors from Springstead High were graduate Josh Carr, sophomore Emily Carr, sophomore William Osborn, senior Eric Gibson, sophomore Isaac Gonzalez, junior Raleigh Forbell, graduate Logan White, junior Dawson Rufa, graduate Ankit Kumar and junior Wyatt Van Meter. Central High participants included seniors and triplets Erin, Ben and James Tracy; graduate Dennis Webb, and senior William Levandowski. Kylie Van Meter is a University of Florida student.