Justin Beckerman, 18, built his own one-man submarine 7 Gallery: Justin Beckerman, 18, built his own one-man submarine

At age 12, he built the "Cleaning Car," a remote-control vehicle that could mop and vacuum the floor.

When his sixth-grade science teacher mused about how nice it would be to have a device that got people to hush or clap on cue, he arrived at school the next day with a homemade quiet/applause sign with lights.

Two years later, he created "Head Entertainment," a helmet gizmo that allowed users to watch close-up videos without ever having to crane their necks.

Over the years, Justin Beckerman, now a junior at West Morris Mendham High School, has designed a miniature boat with lights, a remote-control car with airsoft gun and an "Amusement Ride," a beach chair dangling from wires.

This time, the teenage Thomas Edison has outdone himself, building a one-man submarine he floats under Lake Hopatcong.

Co-existing with Jet Skis and fishing boats in the picturesque West Jersey lake is Justin’s latest invention — complete with lights, paddles, ballasts, air compressors, 2,000 feet of wire and a Plexiglas dome top that looks like the head of Star Wars robot R2-D2.

Justin, who turned 18 last weekend, spent a month designing and five months building his 9-foot-long submarine, into which he can fit.

"By far, the longest project I’ve ever worked on," he said. "The previous one to that was about three weeks, when I built a tree fort."

Why a submarine?

Because it allows him to combine his two loves: Water and making things.

Building a submarine allowed him to integrate all the systems and knowledge he has amassed.

Previously, Justin built a remote-control submarine that was able to dive 30 feet in Lake Hopatcong.

"I saw tons of fish. I even picked up a crowbar and an old light fixture," said Justin, who plans to study engineering in college. "Just learning from experiences like that, I was able to eventually come to this."

White ballast tanks fill with air and water, controlling the height in the water. The submarine, air and pressure-tested, is designed to go 30 feet deep.

It has a motor on back, regulators and valves from an old soda machine, three battery systems, float sensors that can tell when tanks are full or empty, a horn, a CB radio to communicate with people on the surface, and 1,400 watts of lights plus a strobe light.

"When you go down a few feet, it starts to go darker and darker, and when you get to about 10 feet, it can be virtually no light," Justin said.

The submarine has a PA system with speakers and a camera to broadcast a signal from the buoy to a TV screen, allowing people to watch on the surface. Sandbags are used to distribute weight.

The body of the submarine is a drain pipe, capped at the ends. He used a reciprocating saw to line up the corrugated materials, then sealed the plastic with marine-grade epoxy glue.

The invention has set him back about $950, including parts that were used for previous inventions, then disassembled.

It wasn’t his first attempt to build a submarine.

"When I was little, I tried to build something, just for fun," he said. "I took some corrugated plastic and some tape and built a box with little windows and was hoping maybe that would sink. It acted more like a boat."

Neighbors and relatives have learned that "can’t" is not in Justin’s vocabulary.

Instead of making a regular paper airplane, he wants his to resemble a real plane.

He has worked on his submarine with a single-mindedness in the waking hours after crew team practice and homework.

"He doesn’t give up," said Jean Scrocco, a next-door neighbor at the Beckerman family’s summer home in Hopatcong. "He gets an idea in his head and he keeps going until he gets it to work."

Scrocco once was working in her upstairs office when she heard what sounded like an explosion.

She rushed out to the top deck, expecting to see a neighbor’s house blown up. Instead, she found only Justin experimenting with a model boat, having put two D model rocket engines on it to see how fast he could make it go.

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"Call us next time," the bemused neighbor said.

The polite Justin is hardly a Dennis the Menace to his neighbors. He is a teenage handyman who can fix TVs and Jet Skis.

"There’s a whole new thing that occurs in your life when the Beckermans move in next door," Scrocco said. "We never throw out anything electric ever again before you ask Justin first: ‘Are there any parts you need?’ "

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