MIAMI —  A 35-year-old Orlando man can thank his 300-pound girth for helping save his life after he jumped off a cruise ship and drifted 20 miles for more than eight hours with a collapsed lung before rescuers found him in the Atlantic Ocean.

Michael Mankamyer's family thought he was dead. The Carnival Glory cruise ship continued on its scheduled route toward the Bahamas after the Coast Guard arrived. And Mankamyer was left bobbing in the Atlantic Ocean.

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"We were hysterical," Gina Mankamyer, who described her brother as an average swimmer, told the Orlando Sentinel. "We were already thinking about having to plan a funeral without a body."

Petty Officer Ryan Coon spotted Mankamyer about 75 yards from the Coast Guard cutter Chandeleur."I knew that was our guy," Coon recalled. "I hollered out, 'Man overboard, portside!' "

His 300-pound girth likely helped him float easier than someone leaner, said Richard Rotundo, a professor at the University of Miami's Miller School of Medicine specializing in cell biology and anatomy.

"Someone who is really overweight and has excess fat, their body density would be less than water," Rotundo said. Layers of fat also would insulate Mankamyer from the water, the professor said.

Sal Wega, 16, Mankamyer's godson and cruise-ship roommate, argued with him before jumping over the side. Wega wanted to hang out at a teen club but Mankamyer wanted to stay in the room.

Mankamyer called Sal and apologized for ruining the trip, the teen said."I'll always love him," Sal said. "He's my godfather."

Mankamyer was rescued a little before 9 a.m. EDT about 30 miles off the coast of Fort Lauderdale, Fla.

Mankamyer, an imaging technician at Florida Hospital, suffered mild hypothermia and a collapsed lung but was in good condition at Jackson Memorial Hospital in Miami. A witness told the Coast Guard that Mankamyer was drunk when he went overboard.