Students testing underwater robots at the Aptos High School pool Friday afternoon tossed around terms like "positive buoyancy" and "amperage" as casually as if they were talking about a recent baseball game or plans for the summer.

"It has to be positively or neutrally buoyant," said freshman Connor Munger, pointing to the air-filled bottles on his team's remotely operated vehicle named the "Black Pearl."

"Otherwise, it won't float to the surface if the motors break," said Isaac Cassar, Connor's teammate. With a few minor adjustments, Isaac placed the robot back in the pool, and Connor used a set of wired controls to guide it down for more practice picking up "crabs" and "ocean bottom seismometers" from the pool floor.

Since fall, six teams from Aptos Junior High School and Aptos High School have met sometimes twice a week to construct underwater vehicles, complete with motors, propellers and a tether linking the contraptions to the surface. Like the remotely operated vehicles that scientists use to ply the ocean's depths, the students designed these submersible robots to simulate expedition tasks.

The six teams will test the mettle of their machines against those of some 45 other squads from the San Francisco Bay Area and the Central Valley on May 10 at Monterey Peninsula College.

To learn the basics of building a machine that holds up in water and performs critical tasks, engineers and technicians from the Marine Advanced Technology Education Center at Monterey Peninsula College held workshops. There, they provided the teams with pieces of pre-cut PVC pipe and assembled motors and helped them build an underwater robot. By the end of the clinic, the teams had put together a working submersible and had a good idea of how to tackle a project of their own.

"It was like sitting down with Tinker Toys," said Bruce Willy, a volunteer whose son Nathaniel, an eighth-grader, is participating.

Three junior high teams have entries and members of the high school's Robotics Club will field two teams. This advanced level requires students to pick up targets using only a camera mounted on the robot and attached to a monitor on the pool deck, not by looking over the side of the pool.

While most teams were busy tweaking their designs Friday, the Ranger entry was absent from the pool, still grounded for last-minute modifications.

Winners at the May 10 competition advance to a contest at the Scripps Institute of Oceanography in San Diego to compete against squads from around the world.

"They really take ownership of the whole project," said Joe Manildi, a physics teacher and adviser for the Robotics Club at Aptos High School. "What's amazing to see is how much they come up with on their own."