There were seven swimmers at Bushwick’s initial scrimmage. Twelve by the time of the meet. Ms. Taylor managed to get two dozen swimmers who were mostly competitive, despite the loss of her season.

“We’re fast learners around here,” Kyara Rosello (17), was a junior and a top performer in 100-yard freestyle. Jeniffer Montechana, 16, a recently arrived from Ecuador, pulled her over while she was standing on the pooldeck. Jennifer has yet to learn English, but she had picked up enough swimming technique within weeks to become one of the team’s starting backstrokers. Her team consisted of six girls who could not speak English. She used the help of other students to learn Spanish.

Ms. Taylor informed the girls about a swim team in their area, whose fees start at $1,000. But none of the girls were able afford them.

The new swimming team was difficult to convince students.

“Some of our own students didn’t even know we had pool here,” Jorge Sandoval was the chief of the Academy of Urban Planning and Engineering, one of Bushwick campus schools.

Carbajal offered a financial incentive. He guaranteed nonswimmers that he could have them swimming well enough to pass the city’s preliminary lifeguard test, offered every winter. That could mean spending summers in the sun making at least $16 an hour, he said, and also helping with the city’s notorious lifeguard shortage.

He persuaded more than a dozen boys to join — 80 percent of them nonswimmers, he said. He had to pay for some bathing suits himself.

The team has so far won 4 meets, and lost 2 more. The team has a somewhat ragtag feel, but is quickly improving. Although it is the least competitive currently, Brooklyn’s Three boys divisions. Mr. Carbajal promised that the Tigers would be first in each of these categories and then get to compete with perennial swimming champions at top public high schools such as Brooklyn Tech.