Dave March takes a sip of his coffee and looks through the windshield of his car, which is idling in the water in Newport Harbor, Calif., next to his yacht.

“This has been a dream for 10, 15 years,” he says, his gaze fixed toward Catalina Island. “Every time I see that island, I think, ‘Oh, it’s not that far.’ ”

March, 58, has spent more than a decade developing the high-speed amphibious car he is about to take to market for $135,000 apiece. He has taken deposits from the Prince of Dubai, tycoons in Silicon Valley and millionaires from around the world.

On this day, he hopes to prove the car’s mettle by driving it from his WaterCar headquarters in Fountain Valley, Calif., to Catalina Island.

The only problem is he has never tested the car on open water, and 30 miles is a long way to swim.

March has been building and testing amphibious cars, or amphibians, for years. He filed patents for his first amphibian in 2003. Six years later, he set the Guinness World Record for fastest amphibious car with the Python, which has a 450-horsepower Corvette engine and can hit 60 mph on the water.

The car that March is test-driving to Catalina is the Panther, a smaller, off-road amphibian that is the entrepreneurial fruit of 12 years of trial and error and hundreds of thousands of dollars in research and development.

Ever since he posted a video online of the Panther driving on the freeway, scaling sand dunes and impressing scantily clad ladies at a lake, March’s phone hasn’t stopped ringing. The car already has been filmed in three reality shows, including an episode of the current season of “The Bachelor.”

“I’ve got guys that are throwing money at me,” March said. “It’s a fun position to be in.”

Back in Newport Harbor, March points his Panther toward the horizon. He’s surrounded by three powerboats, which are carrying friends, family and a case of champagne, which March’s wife hesitates to put on ice, for fear she might jinx the crossing.

He steps on the gas, and the Panther slowly rises up out of the water. As he passes the other boats, he waves to his family, fingers crossed.

As March moves into deeper water, dolphins leap up around him. The shore disappears from view, and a whale comes up for air.

“It’s running nice,” March’s voice comes in over the radio. “If it weren’t for the swells, I’d kick it up a notch.”

“We’re at 13.5 miles,” March’s partner, Fred Selby, radios from his boat before the halfway mark. “This is the point of no return.”

March is particularly well-positioned to build a successful amphibian. He owns Fountain Valley Bodyworks, an auto repair shop that fixes 500 to 600 cars a month. He also is an avid boater.

March’s goal was simple: Build a car that could drive on the freeway but also keep up with a boat on the water.

“We want to be the Henry Ford of amphibious cars,” March said.

WaterCar has gotten around manufacturing regulations because the company sells the car as a kit. Buyers purchase the body but must pay a third party to install the engine, which, on paper, means the buyer built the vehicle. The owner then must register it as a boat and as a car.

Catalina Island was a foggy blur when March idled into the harbor.

An hour and 10 minutes after leaving Newport Harbor, March stood at the back of his yacht in Avalon Bay and popped a champagne cork into the water.

“I never thought we’d make it the first time out,” March said as his friends and family raised their glasses.