Vadim "Jimmy" Grinzaid has gone mad. He admits as much. Look how the man signs his e-mails: Mad Mad Jimmy.

Some acquaintances, his father even, have worried about Jimmy. Why would a career engineer, well paid and with a wife and two kids, chuck it all for ... Whirlyball? Launch a fun center hitched to a wacky pursuit with the growth rate of a bank CD? Stretch workdays to 16 hours, spilling over to weekends?

Andy Sharp/Staff (ENLARGE)

David Blakely (left) and fellow Weather Channel employee Chris Hill play Whirlyball at Mad Mad Whirled in Marietta. Hill, a supervisor of software developers, shrugged off the afternoon's diversion, saying, 'After this, I'll get more out of them tomorrow.'

A child trapped in an adult's body, Jimmy, 43, has succumbed to the siren song of entrepreneurship. He craved his own business — one that must entertain himself and others, generate revenue, be offbeat.

Above the human and mechanical racket at his Mad Mad Whirled, which opened last month in Marietta, Jimmy says, "I always wanted something nobody else had."

Close enough. Though his hangout offers Laser Tag and inflatable slides, they're all sideshows to his obscure centerpiece — a frenzied team game involving electronically powered bumper cars, a Wiffle ball and basketball-type backboards minus the rims.

Only 35 other such attractions are sprinkled about North America, including Whirlyball Atlanta in Roswell, Jimmy's lone rival in the Southeast.

Jimmy's inner entrepreneurial being was stirred one night four years ago when his boys'-night-out bunch skipped the usual Braves or bowling for something different. No girly stuff, their wives insisted, so they tried Whirly. Next time out on the town, they tried it again.

"When I saw my friends walking off the court for the second time, I saw excitement in their eyes," he says. "Sparks were flying."

Jimmy, who earned an MBA from Georgia State in 1995, sensed he had found his business niche.

Entrepreneurs, by nature, are risk-takers. But, from engineer to Whirlyballer? From the serenity of graphic calculators and drafting tables to the craziness of flashing lights and screaming kids of all ages?

"Seems impossible," Jimmy acknowledges before making the case that problem-solving skills developed in his past life have carried over.

Long-term success is not impossible, only improbable. Of every 10 business start-ups, eight fail within five years — one or two inside a year.

A quarter-century ago, Jimmy could not say or spell entrepreneur, much less define it. He and his family fled the former Soviet Union during a period of persecution against Jews. "We had to leave," he says.

Rejecting the usual metro areas favored then by immigrants, the Grinzaids chose Atlanta, knowing little more than its state produced the incumbent president, Jimmy Carter.

His father, an engineer, had preferred New Zealand. His mother, eager to experience American shopping centers, won out.

Once they moved, there was no shopping other than for necessities. The Grinzaids survived on food stamps in a run-down apartment for six months until Mom secured a minimum-wage job. Dad landed work later, as did Jimmy, then 17, as a youth counselor. It doubled as a cram course in English; kids were willing to repeat words and phrases so Jimmy could learn them.

Georgia Tech degree

He absorbed enough to complete high school and enroll at Georgia Tech, financed by loans, grants, a scholarship and paychecks from a 30-hour-a-week grocery cashier's gig until he graduated in 1986.

A decent job designing wastewater treatment plants awaited Jimmy, the first of three held in two decades of engineering.

"My heart was never really in it," he says. "The seeds of doubt started growing."

They had become a full-blown forest when Jimmy stumbled upon Whirlyball. Late nights at home, he would research the game. A business plan evolved, one that initially lacked some key numbers — financial projections.

Venture capitalists did not break down his door. Not only was Jimmy fishing for funds to bankroll an esoteric endeavor, he was unwilling to put up his own stakes — not even his Dunwoody home as collateral.

Wagering one's house is a time-tested signal to lenders of a deep commitment to an undertaking. As a prerequisite, "it's less true today than it might have been 15 to 20 years ago, but it is still true," says Charles Hofer, regents professor of entrepreneurship at the University of Georgia's Terry College of Business. The pledge, Hofer adds, answers the lender's concern: "Are you willing to go the extra mile?"

$700,000 raised

Jimmy shook down enough relatives, friends and professional investors, two dozen in all, to dig up $700,000 for equipment. Unusually enticing terms got them on board. Jimmy has vowed to take no profits, only salary, until their antes are returned, after which he will keep just 30 percent of the gravy.

One contributing party was the supplier himself, Kim Mangum, president of the equipment company and the de facto Whirlyball commissioner. In the 1960s, Mangum's father designed the vehicles, juiced by low-voltage electrical flow along the floor.

From experience, Mangum says, "The banks notoriously will not lend for Whirlyball. There is no resale establishment for the equipment."

Yet raising capital for fledgling businesses "is slightly easier now," suggests UGA's Hofer, noting that lenders' scars have healed from the dot-com bust.

Jimmy sweet-talked Omni National Bank into a $350,000 SBA loan, even after refusing to toss in his house as collateral.

"My hat is off to him," says Mangum, who visited Atlanta to train his protégé. "Jimmy is a real go-getter. He won't take no for an answer."

Jimmy, with one foot in his two cultures, easily switches from American metaphors to Russian proverbs, a favorite being the cat who finds a ball of yarn and picks at it until the room is filled. "A little thread," Jimmy says, "can turn into a lot."

Picking away at his yarn, Jimmy scouted out three sites for a setting until he drove by an abandoned 10-screen movie complex on Delk Road. Though the owner of the faded pink structure had no clue about Jimmy's project — "What is this Whirlyball?" — he agreed to a 10-year lease.

Jimmy went to his boss at the engineering firm and confirmed an earlier heads-up that he was resigning "to become an entrepreneur." The guy looked at Jimmy and said, "I thought you were kidding."

So did his father. Or so he hoped, having told Jimmy, "This is not for you."

Mad Mad Whirled — the paint barely dry, some attractions not yet operating — plugged in on May 1. "I was so afraid nobody would walk in the first six months," Jimmy recalls.

Despite scant advertising, the calendar began filling with corporate outings, end-of-school parties, bar mitzvahs and quinceaneras. "An avalanche," he says. With additional traffic off the street, he had to put a few job applicants to work within a half-hour.

With any fresh venture, there are missteps. Jimmy was proud of his detailed price list, columnized and cross-referenced, that would have passed muster in his engineering world, but was otherwise confusing enough to require a makeover.

"One spoon of roof tar," he says, excavating another proverb from the homeland, "can ruin a whole barrel of honey."

Dad drops by

Jimmy has won over a key skeptic — his father, who drops by with a toolbox and an eagerness to fix anything in need of repair.

As much as the businessman in Jimmy relishes fully booked courts, the playful Jimmy welcomes a chance, as he seized recently, to jump into a car, stomp on the accelerator, high-five teammates and tap out a "let's-go" rhythm on the car.

And though he fights back a fear common to almost every entrepreneur — "I can't guarantee this will succeed; I can only hope" — this picture tells the story of why Mad Mad Jimmy made a radical career switch:

He is howling like a kid. Or, like a grown-up who has been born anew.