The second America's Cup race of 1980 fell apart in a dying breeze today, but not before a bold maneuver by the troubled challenger, Australia, produced a startling turnabout on Rhode Island Sound.

Australia, which has shown herself to be slower on all points of sail than the U.S. defender, Freedom, trailed the blue American boat around four legs of the six-legged Cup course.

Then, on the fifth leg, with the breeze disappearing, she took a gamble, heading far off course in search of a wind shift.

Eventually the wind did shift. When she and Freedom crossed paths again the Australians had wiped out a 1-minute 42-second Freedom lead.

It was an amazing feat but a Phyrrhic victory. The race never ended because both boats exceeded the maximum time alloted for racing -- 5 1/4 hours. bThe contest was abandoned shortly after Australia rounded the fifth mark.

Although it goes in no record book, Australia had put together a stunning lead before the race committee canceled the contest.

She was ahead by close to half a mile at one point and, after the race, Australia syndicate manager Alan Bond said, "Quite frankly, we felt we were very unlucky not to have won the race. If the wind had filled earlier, we'd have finished and it would be on the board as a victory for us."

A win for Australia would have tied the best-of-seven series at 1-1.

"We're disappointed in that," said the jocular Bond, "but I do think our performance was better today."

Before the light-air turnaround, there had been little for Australia to cheer about.

She had trailed all day, providing only one brief earlier moment of excitement for her followers.

Australia skipper Jim Hardy lost the start in moderate breezes to Freedom's Dennis Conner. But, after crossing the line a boat length behind, Hardy somehow powered his sloop past the blue boat and briefly took a lead.

Conner came back in a series of tacks, however, regaining the lead and building it to 42 seconds by the time they reached the first buoy.

Conner then extended his advantage through the next three legs of the race until he was ahead by 15 boat lengths or more when the two yachts turned for the next to last leg and the wind began abating.

Hardy headed far to the left side of the course and Conner briefly bore off to stay with him. But the Australians and their lighter boat seemed to move better in the next-to-nothing breeze. Eventually, Connors split off and headed away, seeking his own breeze.

Both boats drifted more and more listlessly, staying far apart for half an hour before Australia finally turned back toward the next buoy. She gained in a freshet or two, while Freedom seemed to drift backward with the tide and when the two crossed Australia was in the lead.

Slowly the breeze began to fill and Australia picked up more and more of an edge. As the yachts approached the mark she was up by nearly half a mile, though it was by then impossible for the race to be completed.

Both skippers knew by then the race would go down as an incomplete. Connor said his navigator, Halsey Herreshoff, becan computing the necessary speed Freedom would have to make to beat the abandonment gun while they were slatting around in the empty breeze.

"The first time we figured it out, we had to make somethng like 5.2 knots over the bottom. Every few minutes, Halsey would refigure it. I think the last time he did it came out something like 220 knots."

Australia rounded the final mark to the bleat of horns from her tender, Fire Three. Freedom was far away on the horizon under the blue of clearing skies.

Three minutes later time ran out and the committee ended the competition.

It was, according to one Cup historian, the greatest lead for a challenger in a Cup race since Endeavour led Rainbow by 6 minutes 39 seconds in 1934.

It also marked the first time that a challenger had rounded a mark ahead of defender in any Cup race since Gretel II defeated Intrepid in one race in 1970.

While Connor was clearly not happy with the developements, he said the Australians' decision to go on their search for wind as involving "a certain element of chance. If the wind had been filled from our side it would have been us ahead," he said.

And Connor added, "We did sail very well all day in fairly light winds. We opened up our lead in every leg when there was sailing wind."