“It’s 6,400 feet of track,” Mr. Miller said. “We had so much track to work with, we said, ‘Let’s do some really cool stuff.’ ”

The Gravity Group works on wooden coasters, which have rails made from laminated pressure-treated pine, laid on wooden boards called ledgers, with only thin ribbons of steel where the car wheels make contact. There are purists who say the supporting structure must be of wood, too, but the Voyage is one of many wooden coasters — the Cyclone at Coney Island is another — with steel supports.

New wooden coasters are relatively rare these days, as park owners opt for steel-rail designs that are generally faster and higher (and less expensive to maintain) and have more queasiness-producing features like barrel rolls and corkscrew loops. But the Gravity Group is churning out designs. A small coaster opened last year, to positive reviews, at Quassy Amusement Park in Connecticut, and the group has undertaken several projects in China, where the growing middle class has fallen head over heels for amusement parks.

The Voyage, built in 2006 at a cost of $9.5 million, remains the company’s signature ride, consistently ranked among the top wooden coasters in the world by what are politely called coaster enthusiasts.

Mr. Miller, with his shaggy haircut and earrings, is something of a rock star among these fans, who think nothing of traveling thousands of miles to ride a particular coaster, over and over and over. About 450 of them showed up last month for a weekend event at Holiday World that included some after-hours riding in the dark. Mr. Miller showed up as well, bringing along a steel plate left over from a job in Sweden that he and his partners had autographed for a charity auction.

Enthusiasts say all three of the park’s coasters are excellent, but the Voyage gets the most accolades.