Almost everything about the International Watercross Association (IWA) seems counterintuitive, starting with its basic mission.

That would be racing snowmobiles across open water.

"We get a lot of 'How is that possible?' looks and questions," said IWA president Derek McPheeters, 30, of Isanti, Minn. "It kind of goes against logic, a snowmobile on the water."

Ya think?

And how exactly does it work? "To be honest, I don't really know the physics of it," McPheeters said with a hearty laugh. "I just know it works. I should have paid more attention in science class."

McPheeters and 50-plus mates, who hold a five-race circuit across Minnesota and Wisconsin every summer, actually have a pretty good idea of what they're doing. They have rigged their wintry machines not only for open-water racing but also for dealing with the inevitable downward plunges.

"You stay up as long as you have gas," said Chad Maki, 21, of Inver Grove Heights. When the sleds sink, pontoon boats winch them back up with cables that attach around the chassis.

Even that can turn into competition. The most recent IWA event in Grantsburg, Wis., included a "Pit Crew Challenge" in which racers and their pit crews intentionally sank their snowmobiles, then raced to see who could get their sleds running and complete a lap on the water. Jason McPheeters and his pit crew of Justin Gully and Wade Lund won with a time of 1 minute, 37 seconds.

In the overall competition, defending champ Maki is vying with Dale Lindbeck for first place in both the open and stock classes, with races remaining in Ely (Aug. 11-12) and Brainerd (Sept. 15-16; for info, go to iwausa.org).

The sport actually dates to the 1970s, when snowmobilers started tweaking their machines to ride year-round. Maki's father, Mark, won the first World Watercross Championship in 1977 on a straight-line course of just over a quarter-mile.

Soon the riders wanted to go farther and created oval courses. But working the curves turned out to be counterintuitive.

"We actually have to turn our handlebars the wrong way," McPheeters said, "because the back of the ski goes down and acts like a rudder, It's the back of the ski that turns it, not the front. ... It takes only once to figure that out [laughs]. There's also a lot more body English that's required."

Along with riding techniques, the machines themselves get a few adjustments in the modified division. "We adjust the clutching so it will pull on water," Maki said, "and tweak the suspension so it will bank the way you need it to."

He added that the modified snowmobiles generate up to 200 horsepower and reach 80 miles per hour, about 10 mph faster than the top speed of personal watercraft but way short of the 140-mph speeds the same snowmobile riders can attain on ice.

And, of course, some competitors find a way to get a little bit more out of their sleds than others. "The machines are so close in technology and speed," McPheeters said, "that I would say 85 percent [of the difference between winning and losing] is the driver."

Like their NASCAR counterparts, the IWA drivers dress in colorful racing garb (sans most of the brand logos) and compete on a circuit that awards season titles based on overall points. The same goes for other circuits in Europe (the sport is -- surprise -- quite popular in Scandinavia), Canada and New England.

The more modest stakes and the general fellowship that comes with watercross have created a camaraderie among the drivers.

"This is not a huge sport," Maki said, "and we're not trying to get rich. We're pals. If someone is having trouble, it's not unusual to see someone loan them parts. In Grantsburg last year, a guy blew out a gasket and we gave him a gasket. And then the next morning I had to race against him, and he beat me."

Bill Ward • 612-673-7643