For the first time, the students saw how all the pieces of a sailboat fit together, including its crisp, white sail. While learning how to hoist the sail, they handled colored ropes of varying thicknesses — black, red, blue and black and orange, which attach the sail to the boat.

“We call them lines,” explained Mr. Wasylyk, the English teacher, who is a lifelong sailor with a captain’s license and the owner of a 38-foot sailboat he has skippered to Nova Scotia. “You call them string or ropes, but once you’re on a boat, you call it a line.”

Brooklyn Boatworks then transported Pizza Sail, as well as the finished Optis from the other schools, to a workshop in Gowanus. There, Boatworks staff members coated them with epoxy (a more toxic kind that the students were not allowed to use), varnish and fiberglass tape to make the boats watertight.

The new Optis will join a fleet of those built in previous years, which are made available to former student builders and groups like the Girl Scouts, during the summer. The boats are stored in multiple locations in Brooklyn, including the Pier 5 Brooklyn Bridge Park Boathouse. The very first student-made Optis are at Derecktor Shipyards in Mamaroneck.

For some Boatworks alumni, the program’s lessons resonate years later.

Jovon Ferguson, who graduated from Wheaton College in Massachusetts last year with a degree in political science, helped build an Opti when he was in seventh grade at the Brooklyn Collaborative School. He works with Brooklyn Boatworks once a week.

Now that he is leading students in the process, Mr. Ferguson says he appreciates the bond that boatbuilding as a team can produce. “Every day it’s there, that we’re doing that rare thing together,” he said.

“We collect students’ cellphones at the start of each class,” Mr. Ferguson said. “It really draws in a student who wants to do something different.”