Jon Lugbill is to whitewater paddling as America's Cup champion Dennis Conner is to sailboat racing -- a man who leaves nothing to chance.

"Jon probably knows more about canoeing than anyone in the world," his coach, Bill Endicott, says of the defending world solo whitewater canoeing champion.

After the U.S. team won overall honors at the biennial world competition in 1979, Endicott put together a book describing how Lugbill and other Americans got so good at a sport that traditionally had been the province of Europeans. What it showed about Lugbill was an astounding capacity to work. "It was simple," said Endicott. "Jon had more practice runs than anybody else."

Now everyone knows that and that all the pretenders to Lugbill's throne are redoubling their practice schedules. Which just means Lugbill works that much harder.

Last week, before heading off for the 1981 worlds which will begin this week in Bala, Wales, Jon and older brother Ron, also on the U.S. team, sat around a well-worn family dinner table in Fairfax and talked about the strange twists and turns that have taken them to the peak of a sport that remains a mystery to most Americans.

They are not products of a high-pressure sports family. They got mixed up in whitewater racing almost by accident 10 years ago when Jon, Ron and brother Kent put together a wacky entry in an April Fools raft race at Petersburg, W.Va.

They found out when they got there that Jon and Ron were too young to race anyway, so papa Ralph and Kent raced while the younger boys watched from shore. They saw rafts go by, but they also saw kayaks and canoes battling the rapids and that whetted their interest.

That fall the Lugbills bought a kayak. A year after that they picked up their first two-man decked canoe and Ron and Jon began racing in it. By the fall of 1974 the two youngsters had a top-quality used two-man racing canoe and were winning enough local races that they started thinking about big-time competition.

Word was getting around about the brothers, then aged 13 and 15. "Everyone told us we had had a chance to make the U.S. team," Ron said.

Washington enjoyed a warm winter that year and the two young Lugbills spent their afternoons and weekends paddling in the Potomac below Old Anglers Inn, cadging rides to the river from their folks. They sent away for a training manual and didn't find out until they started racing the following spring that they'd taught themselves to paddle out of sync with each other. It mattered not. They went fast.

"Everybody said, 'Wow, those guys are onto something new,'" said Jon, with a laugh. "We just didn't know what we were doing."

The Lugbills qualified for the U.S. team that spring and finished 22nd out of 26 boats in the C2 class at the world championships in Skopje, Yugoslavia, Jon being the youngest U.S. paddler ever to compete.

"They came back from those races really upset," their father said. "They wanted to be competitive at the world level, not just make the team. And after that they really started to train."

The first thing the Lugbills did was get rid of the two-man canoe and buy two solo boats. "We paddled every day in 1976 and again in 1977," said Ron. "We were doing more than anyone had ever done before in the United States."

It still wasn't enough. Ron made the U.S. team in C1 for the '77 worlds and finished sixth.Jon wasn't among the four C1 paddlers selected. Both competed in C2, Jon with neighbor Bob Robison and Ron with David Hearn. The U.S. C2 wildwater team won the overall bronze medal.

Success? "We didn't think so," said Jon. "We expected to win."

When they went back to Oakton High School that fall the Lugbills discovered that the cross-country team was working out both mornings and evenings. "Here was a high school team training harder than us," said Jon, "and we were supposed to be world-class athletes. We figured we'd better start working."

About that time Endicott began overseeing the training of the growing cadre of world-class paddlers in the Washington area, and two-a-day workouts and year-round training became standard procedure. The playoff came in 1979 at Jonquierre, Quebec, when Jon Lugbill and woman's kayak gold medalist Cathy Hearn led the U.S. team to overall victory.

Now the pressure is on to repeat.

"The old theory used to be, you paddle six months a year and then do something else to complement it the other six months," said Ralph Lugbill. "These guys (Ron and Jon) decided they had to do something to catch up with the rest of the world, so they went at it all year. Then they realized it was the best way, anyway."

Only trouble is, now the rest of the world has realized it, too.