NEWPORT, R.I., OCT. 1 -- The bedraggled U.S. effort to defend the America's Cup is due for a major boost this week when one of the nation's wealthiest men throws his yachting cap into the ring.

Industrialist Bill Koch, 50, founder and president of the billion-dollar Oxbow Corp. and owner-skipper of the hot new maxiboat Matador 2, was in California over the weekend hammering out details with Cup regatta organizers.

Assuming no last-minute glitches develop, he plans to announce in New York Wednesday a multimillion-dollar campaign to defend sailing's top prize when racing begins off San Diego in January 1992.

Koch's entry, with the weight of his personal fortune behind it, marks the first adequately funded U.S. Cup defense effort. Two other syndicates -- one headed by Cupholder Dennis Conner and the other backed by the Beach Boys singing group -- are scratching for corporate sponsors to finance their $20 million to $30 million operations, but both have a long way to go.

Meantime, a dozen challengers from nine nations are gearing up for the next assault on yachting's grand prize. Japan, France and Italy all have new, 75-foot America's Cup Class boats in the water, while no U.S.-made boat has yet come off the ways. Italian billionaire Raul Gardini has two Cup boats sailing in the Mediterranean, another under construction and an almost unlimited budget.

"He's impassioned with the challenge of winning the America's Cup," said Gardini's professional skipper, U.S. expatriate Paul Cayard. Now, it appears, so is an American of means, Koch, who enters the fray late but with resources comparable to Gardini's and those of the well-heeled Japanese Nippon Challenge.

Koch's decision wasn't easy. A tall, slender man who assiduously dodges public notice, he never intended to get mixed up in Cup intrigue. "There is a lot of nastiness, it's very cutthroat, highly commercial, very public," he said. "Good friends become lifetime enemies. I had other priorities."

But when Koch's snow-white, 85-foot sloop Matador 2 blew away the competition here last week in its maiden maxiboat regatta, winning five of seven races on Rhode Island Sound, it confirmed his suspicion of a technological breakthrough in design.

Koch, who holds a doctorate in engineering from MIT, thinks the secrets of Matador 2 can be transferred to a Cup Class 75-footer. "Every other U.S. syndicate has approached me for my money and my technology," he said. "That convinced me we had a window of opportunity."

Koch also was prodded along by his longtime tactician, Gary Jobson of Annapolis, who twice sailed for the Cup with Ted Turner and will play a key role in Koch's effort, relinquishing his job as ESPN's TV sailing commentator.

With financing already largely under control, Jobson and Koch envision an old-style, Corinthian campaign in sharp contrast to the highly commercial efforts planned by other Cup aspirants. Regatta organizers have approved advertising and corporate logos on boats, sails and crew uniforms for the 1992 races, but Koch said there will be none on his team.

"I like doing things contrarily," he said. "I thought, 'We can do a program without turning it into the Indianapolis 500.' "

As for corporate help, he said: "We'd want it, but not to run a spinnaker up with a logo on it. We're looking for technological and organizational help in a kind of national effort rather than, 'We'll sell you our spinnaker {as a billboard} for five million bucks.' "

If Koch is bucking a trend, he apparently can afford to. He sold his share of his father's Kansas energy company, Koch Industries, to his brothers for a reported $620 million in 1983, then founded Oxbow and turned it into a billion-dollar operation in oil, coal, plastics, computer technology, geothermal energy and publications.

He evidently liked a flattering 1988 cover profile of him in New England Business so much, he bought the magazine for a reported $2 million.

Koch got into yacht racing in 1984, buying an older maxiboat called Huaso, refurbishing it and renaming it Matador. While racing against Gardini and others of the Concorde set, he launched a yacht design competition at home to fashion a new, world-beating maxi.

Four years and many millions of dollars later, he unveiled Matador 2, several feet longer, 25 percent heavier and wildly different from her rivals beneath the waterline. Her keel -- reportedly a thin blade of stainless steel with a huge lead bulb at the bottom -- is kept shrouded from prying eyes like that of the winged wonder, Australia II, which turned the yachting world on its ear when it captured the Cup here in 1983.

Last week was the acid test for the unique design, and Matador 2 passed with flying colors. "The boat is superb," said Koch, beaming after winning the first three races. "There are a few little changes to make, but no major mistakes."

The question now is whether his success in the courtly maxiboat game can be transferred to the shark-infested waters of the America's Cup. "There are aspects {to a Cup quest} that can be a nightmare to someone who never did it before," said Adam Ostenfeld, crewman on Conner's 1987 Cup winner Stars & Stripes, who now works for Gardini.

How the softspoken, deferential Koch handles the sort of armor-piercing, public attacks on sportsmanship and fairness that have characterized the Cup in recent years will be interesting to see.

Meantime, he said he hopes to steer his own boat, something no amateur helmsman has succeeded at since Turner won in Courageous in 1977. The sport today is dominated by professionals like Conner, Cayard, Beach Boys skipper John Bertrand and the Nippon Challenge's hired gun, New Zealander Chris Dickson.

But Koch "wouldn't want to be involved unless he had an active role on the boat," said Chauncey Dewey, a fellow member of the New York Yacht Club.

"If I'm good enough, I'd like to do it {steer}," said Koch. "If not, we'll find someone who is."

In addition to Jobson, he has enlisted the help of Olympic gold medalist Buddy Melges and 1989 Yachtsman of the Year Larry Klein. Some veteran Cup observers say that sounds like a formula for disaster in itself, combining all those egos and all that talent in one boat.

"The point," said Koch, "is that it's not a one-man show. We have a saying on Matador that everyone is equally important; I just write the checks."

Which takes care of the first and biggest Cup hurdle, anyway.