Stephen R. Barton was looking forward to spending the summer at his family's vacation home in the Bahamas before returning to Florida Atlantic University for his senior year.
He left his 25-foot sailboat in a friend's care and put on hold his plans for a human-powered submarine that he hoped would break the world speed record for vehicles of that type.
He never got to the Bahamas. And the submarine he designed may never be built.
Barton, 20, of Hernando Beach, was declared brain dead Tuesday morning, the day after his family's plane crashed, Pasco County Sheriff's Office spokesman Jon Powers said. A spokesman at St. Joseph's Hospital in Tampa said Barton remained on life support Tuesday evening.
Barton was the most seriously injured when the plane carrying him, his parents, his sister and her boyfriend, all of Hernando County, crashed Monday morning shortly after taking off from a private airstrip in central Pasco.
Three others remained hospitalized Tuesday, family friend Jody Sizemore said. Barton's mother, Patricia, 48, was in critical but stable condition at Bayfront Medical Center in St. Petersburg after surgery to repair internal injuries. His sister, Nicole, 17, was at St. Joseph's and was doing well. Her boyfriend, Daryl Naughton, 19, of Weeki Wachee, was in stable condition at Bayfront.
Barton's father, Stephen J. Barton, 48, suffered a fractured wrist. He was flying the single-engine Piper Cherokee 6.
The National Transportation Safety Board is investigating the crash, said Mary Ann Cassano, a spokeswoman for the Federal Aviation Administration.
The younger Barton, like his father, held a private pilot's license but was better known for building submarines.
A submarine the younger Barton designed while a student at Central High School made him the first Hernando County student to win the International Science Fair. His design skills led Florida Atlantic University to recruit him to study ocean engineering after his graduation from Central in 1993.
At the time of the crash, Barton was designing a submarine he hoped would break the world speed record for human-powered submarines and was about to start building it.
"The whole field of ocean engineering has lost a remarkable young man," said Raymond McAllister, the professor who recruited Barton for Florida Atlantic.
_ Staff writers T. Christian Miller, Teresa D. Brown and Kelly Ryan contributed to this report.