Keeping the Cup will be no waltz for Aussies

After using the right stuff in the right puffs to win the America's Cup, Australia's intrepid sailors will soon feel a tidal wave coming over their stern.

All manner of expense, burdens, and stiff challenges will come thundering down upon the Aussies now that the silver vinegar urn, long bolted on an oak-table perch at the New York Yacht Club, has landed ''down under.''

Hosting the contest is no waltzing Matilda and, like the Japanese attack on Pearl Harbor, the Aussies have awakened a sleeping giant in the United States.

Even before Alan Bond's Australia II won the fourth of seven races Monday by a slim 41 seconds, American sailors from San Diego to Marblehead, Mass., were devising fresh campaigns for a Cup challenge, expecting it to be held in the Indian Ocean off Perth, in Western Australia.

In a congratulatory note, President Reagan said he was delighted Australia would be the Cup's new home - ''at least until the next race.''

For the United States, the loss was sic transit gloria. Like Captain Ahab hunting the white whale, the cry will now go out: Up anchor, crack it on, away to Perth, and blow those Aussies down! For there was no joy in Newport as mighty Dennis Conner struck out at the helm. The Liberty skipper, who wrote a book entitled ''No Excuse to Lose,'' said afterward, ''We have no excuses. They had the better boat.''

But among New York Yacht Club members, there were a few silent sighs of relief. After sponsoring the Cup races in 25 challenges over 132 years, the club no longer has to pay the several hundred thousand dollars it costs to run the event. Nor will it miss the spotlight of public criticism for appearing not to go overboard in playing fair with Cup rules.

Such troubles will follow the Australians in the wake of their victory. After all, they were masters in harassing the New York club. Now, the hunter is hunted.

Then, too, the Australians will have to abide by the ''deed of gift of the America's Cup,'' the document set down in 1887 for governing the contest. It rests in the New York Supreme Court. Not only does the deed dictate the name of the event (named after the yacht America, which won the British ''100 Guineas Cup'' in 1851), but any major changes to the rules will require the Royal Perth Yacht Club to go before an American judge.

The deed, established to promote ''friendly competition between foreign countries'' forever, stipulates that any yacht club, ''having for its annual regatta an ocean water course on the sea, or on an arm of the sea, or one which combines both,'' is entitled to challenge for the Cup.

This means any legitimate yacht club in the world can launch a campaign against Australia. This year, the New York club had seven challengers. The next contest - most likely to be held in 1986 or 1987 - could have even more contenders.

Australia has shattered the myth of American supremacy in yacht racing (just as the United States did against Britain) and evaporated the mystique surrounding sports' longest winning streak. Sports is just the latest area in which Australia has had its presence felt in the West. There are, of course, the waves of Australian films, books (''The Thorn Birds''), and music. (The song ''Can You Hear the Thunder?'' by the popular Australian band ''Men at Work'' was used as Australia II's theme in Newport.)

Still, the victory cannot be truly given to Australia as a country. The race no longer clearly tests nation against nation, but sailors against sailors. Unlike previous Cup races, this one allowed challengers to use superior American sails - a great equalizer in racing. Australia II skipper John Bertrand not only heads up the Australian loft of the top American sailmaker, North Sails, but received an ocean engineering degree from the Massachusetts Institute of Technology and once crewed for Liberty skipper Conner. Also, the Aussies relied on a US computer and used Dutch expertise when tank-testing their wondrous winged keel in the Netherlands, where the keel is patented.

Ironically, it was the revolutionary hull shape of the yacht America that won the ''100 Guineas Cup'' from Britain in 1851. But Lexcen's Lightning, as the unusual keel is called, can take only partial credit for Australia II's win. ''There's no one thing that accounts for victory,'' said yacht designer Ben Lexcen. ''The keel won't win a race if the crew and boat are bad.''

American sailors admit they just never thought up this mix of tricks in a keel. It was real innovation, giving the boat better speed and better ability to point into the wind. The bottom edge sticks out like a farmer's plow, pushing water eddies up against the hull, where they do less damage to speed.

The fins, like airplane wings, slightly lift the boat and move the tiny eddies away from the keel. They help keep the boat from bouncing like a hobbyhorse and from being pushed sideways when the craft is heeled over. Filled with lead, they put the boat's ballast very low, allowing the hull to be narrower than usual. This allows the boat to turn faster in the Cup's unique tacking duels.

Liberty had its own trick: It had been designed to remove weight from the keel if needed. It was needed, and some 900 pounds of lead were removed for the final race to compete in lighter airs.

In the end, however, Bertrand outsailed Conner at critical points. Conner, after one loss, admitted that anyone who saw the windshifts coming must have had ''X-ray eyes.''

Afraid of Australia's keel, the Americans generally tried to sail for fresh wind on the course, relying on local knowledge of the waters, rather than try to beat their opponent boat for boat in tacking duels. This tactic failed, as was clear on the next-to-the-last leg in the last race: Liberty blew its lead by failing to ''cover'' Australia while looking for the best breeze. Equipment failures plagued both boats, accounting for wins or losses in three races. Both boats had rigorous racing all summer.

Still hanging over the Australian win, however, was whether the winged keel was legal. Many American sailors contend it gives extra draft to the boat. But the New York Yacht Club gave up protesting the keel after being embarrassed at even trying to win by the rules and not on the waves.

That kind of treatment the club can now give to the Royal Perth Yacht Club.