Boat for sale. '74 Sparkman & Stephens aluminum sloop, 65 feet, for seven years the fastest of its type in the world. Cheap. Call R. E. Turner III, Atlanta.

There is no better bargain than a 12-meter whose time has come and gone. Monday morning Courageous was competing for sailing's most coveted prize; Monday night she was on the auction block.

"We've already had one offer," said Marty O'Meara, the Courageous project manager. "Some guy with a sailing school. He wants to use it there; then, you know, for the 1983 campaign, I guess. Or so he says."

Around the bend from Courageous' slip, Pelle Peterson's 12-meter Sverige is for sale, too. The ad for her will have to be more carefully worded, to conceal the bitter fact of her failure in the 1980 America's Cup. Of seven competitors, she was far and away the slowest.

For the last four months Courageous and Sverige have been the objects of impossibly loving attention. Each day when they returned from racing or sail testing they were hoisted, like dinghies, on chains out of the water.

The crew gathered around and scrubbed the boat's bottom with determination, detergent and rubbing compound, to remove any vestiges of oil or tiny blemishes in the paint. Imperfection in the hull were faired out with patching compound for a sleek and perfect underwater profile.

Today, Courageous bobbed in the dirty water at her dock, the object only of passing glances. She is done now.

Like a champion in any sport, this two-time winner of the Cup suffered the ravages of time and ultimately lost her legs. Someone came along faster and newer.

"But these boats have a life of their own," a veteran Cup observer said.

That view was echoed by the Australians in this year's campaign when they were on the edge of defeat at the hands of the Swedes. Gear breakdowns had cost them two straight races; another loss would have put them out of the competition.

"We've let the boat down," said Warren Jones, the Australian syndicate manager.

Courageous' gift to the legacy of 12 meters was her capacity to charge through a head sea. She was among the first aluminium 12-meters, and advances in her design did away with the traditional problem the twelves had of hobbyhorsing to windward in big seas.

Her bow and stern ends were lighter and she seemed to bound like a greyhound from wave crest to wave crest.

Now all the boats can do that, some better than Courageous.

"They had seven years to study her lines and make something faster," O'Meara said Monday, the day Courageous was finally ousted.

It was inevitable that someone someday would.

The development of yachts to race in America's Cup is pure science.

In arguments over the merits of the Cup the parallel most often cited is the Apollo programming when the U.S. decided to go to the moon. It's not a ridiculous parallel.

Twelve meters must be built to specific rules regarding waterline length, breadth, sail area and other critical factors.

The design requirements have been outdated by innovation in yacht construction. But they are constants, impossible constants, and when a designer sits down to draw a 12-meter he faces his hardest test: to advance somehow something dozens of the best designers in the world already put their finest hours into.

The seven 12-meters that came to Newport probably represent an expenditure of $10 million to $15 million just as a broad guess. That includes the cost of campaigning them.

Maybe the Cup is a game for the very rich, but it's one that any romantic can share in, just by watching the big yachts sail into harbor. The effects of advances in 12-meter hull and sail designs and construction find their way down to the smallest dinghy, even to workboats.

The switch to aluminum seven years ago, for example, gave a terrific boost to the use of this excellent metal in boats. Today aluminum work boats and commercial fishing boats are gaining in the marketplace. What could make more sense, with petrochemicals and wood growing harder to find and more and more expensive?