In just over a week, the Brown University senior will batten down the hatch and take the submersible on its first major voyage: dropping into the murky depths of Massachusetts' Long Pond.
Weighing just under two tons, the steel machine is a product of Bagge's pluck, mathematical prowess, and charred skin — a byproduct of 15 straight hours of welding, he said.
Brown's labs have supplied him with air tanks, the university's race car team gave him rights to use metal working equipment, and one professor paid for part of the submarine's yellow paint job on the condition that he would get to choose the color.
"He said I like the Beatles, I want a yellow submarine," said Bagge.
The project, launched in an engineering class that pushes students to build something of their own, is the talk of the department.
Bagge completed the blueprint using design program SolidWorks, careful to map out crush points — spots that could be susceptible to pressure — for varying sub shapes at different depths.
Then he decided to build it himself using steel, imported parts, and intricate electronics to gauge pressure and direction.
"They thought I'd give up on it," said Bagge.
It's been a challenge. Bagge has burned through triple the amount of welding materials the Brown race car team uses in a year. He has lost more than a few shirts to battery explosions and welding mishaps. And a tool known as a grinder, designed to strip rust, left a hefty scar.
"I've come home upset," he said, of his battle scars. "That sub has my blood, sweat, and tears."
But Bagge got some help along the way. There was psubs.org, a Web site for personal submarine designers (who knew?). And advice from Kip Bradford, an engineering instructor who worked with him to iron out "design challenges."
At the moment, Bagge is storing the submarine at boyfriend Asher Dunn's workspace at Keeseh Studio in Pawtucket's Hope Artiste Village. And steeling himself for what he insists will be a safe plunge to the sub's maximum depth of 30 feet.
He has installed a weight-drop system that meant to shoot the sub up to the surface in a bind. And the scuba diver keeps an air tank with him in case the hull becomes flooded.
But Bagge's favorite precaution is a clear dome, on the top of the sub, that houses his head. It's an inch thick, allows him to see from all angles, and will not fracture if hit by a speeding watercraft or placed under extreme pressure.
Or so he says.
"I do not want a propeller blade coming at my head," said Bagge.
To be doubly sure, Bagge has been testing the submarine at smaller depths to work out the kinks. But for the big dive, he plans to stay submerged for about an hour and watch the algae-filled world go by.
"I've been ready to go down for months."