If Dennis Conner left little to chance in 1980 when he won 45 of 51 yacht races to capture sailing's top prize, the America's Cup, you ought to see him now.

In sleek blue Freedom, Conner had the fastest 12-meter yacht in the world by a nautical mile. He still has her, refurbished and race ready, but now he's built a fleet around her.

Conner over the past two years commissioned two of the top yacht designers in the world -- Johan Valentijn and the Sparkman & Stephens firm -- to draw plans for boats that might beat Freedom.

Then he had both built, giving him three boats to pick from when he defends his crown in 1983. By this month, the discouraging consensus was that neither was faster than his old boat.

What to do? First, revisions are under way to upgrade the new boats, "Magic" and "Spirit of America."

If that fails, "The rumor is he's going to build another boat," said Gary Jobson, member of the only American camp to challenge Conner.

Nor would Conner, who won the nickname, "The Machine," for his flawless 1980 performance, rule out the possibility of a fourth boat for his camp.

His cover-all-angles approach does not sit well with his opponents. Tom Blackaller is helmsman of the rival new American 12-meter, "Defender," in which he and Jobson will try next summer to unseat Conner for the right to defend the cup. Says Blackaller, "Dennis is trying to squeeze everybody else out of the competition."

In blunt language, Blackaller contends that Conner's aim is to make the cup competition "so expensive and drudgerous that no one else will try. Dennis wants to corner all the money, all the boats, all the crew, all the gear. He wants to buy it all and sail away on his own."

The assessment amuses Conner, who says his aim in commissioning the two new boats was to make sure that if a radical new design were to sweep the cup competition next year, it would be an American design and not one from the six foreign contenders seeking the crown.

As for Blackaller's argument that Conner would rather have no U.S. competition, he said, "Tommy's missing the boat on that. Our best defense is in having a strong U.S. entry, and you have to have competition for that."

By Jobson's calculation, it's still 12 months and some days until the first America's Cup race next year, but already eight yachts are sailing daily on Rhode Island Sound, including the French and British entries. Both American camps are watching the days tick away and feeling the pressure build. "We're in a race against time," said Jobson.

Along with the eight 12-meters here, others are built or abuilding in Canada, Italy and Australia. Six new 12s have been completed for the 1983 races and four more are possible.

In the face of this unprecedented international attack, Conner's Freedom Syndicate and the Blackaller/Jobson/Dave Vietor group are working to see that the record of U.S. domination (24 successful defenses since the cup was first captured in 1851) remains intact.

The American contenders lie within 50 yards of each other here, Conner's boats at the Williams & Manchester boatyard; Defender and her stalking horse, the venerable 1977 champion Courageous, next door at Newport Offshore. Both sail the same waters every day, but they rarely cross tacks and few words and no information pass between the camps.

The skippers are as different as their programs--Blackaller a boisterous, broad-chested ex-linebacker; Conner a paunchy but iron-willed curtain manufacturer with a penchant for organizational perfection.

And while Conner clearly is the favorite to win the trials next summer with one of his multitude of vessels, he said he considers the Blackaller/Jobson/Vietor combination a more formidable challenge than the two he faced in 1980 from a preoccupied Ted Turner and neophyte Russell Long.

Both camps will race and test sails in Newport through September, then move to separate venues on the West Coast to practice through the winter. Conner already has 400 hours of practice time on the water since his boats were launched in early May. The Blackaller crowd is way behind, with about 150 hours since the late-June launching of the Dave Pedrick-designed Defender, which so far has shown speed only about equal to that of 10-year-old Courageous.

Jobson, a veteran of the 1977 and 1980 Courageous campaigns, says time on the water isn't everything. "Quality of practice is more important," he said. But it was clear from one session last week, when an itinerant newspaperman was pressed into service to fill out the crew on Defender, that organizational wrinkles haven't all been ironed out. In Conner's camp, things are moving smoother.

By next spring, when the two camps return to Newport, more will be known. Conner will know the strengths and weaknesses of Magic, Spirit and whatever other boat he might build against the known capabilities of Freedom. Defender's capacities against Courageous will be known.

But until the two camps meet in their selected vessels for the June trials, no one will know what they can do against each other. That there are no constants other than head-to-head competition is the abiding allure of 12-meter match racing. "You can't tell anything from a stopwatch," said Blackaller.

Even less will be known about the speed of the new British yacht, "Victory," or Australia's "Australia II," Italy's "Azzura," the redesigned "France II," the refurbished Swedish "Sverige" or the Canadian 12 that isn't even finished, and may not be if funds are not forthcoming.

Save those answers for September 1983, when the greatest international yachting event of all is held for the 25th time.