Rumor hops about the docks here like a one-eyed pirate with his peg leg on fire.

From afar, the America's Cup races are seascapes in pastels. We see white sails filled as a seamless boat of elegant curve leans into seaspray coming off the ocean blue. Be still my heart against the mad desire to leave behind the mortgage and go down to the sea in ships.

From afar, we see rich folks throwing millions into the brine without even the chance at turning a profit. The America's Cup, we are told, is for sailors who not only are amateurs of pocketbook but also amateurs of heart. If God (they ask) didn't mean for man to race yachts, why did He make all that water?

Your yachting correspondent is happy to report that beneath this America's Cup elegance and purity there resides the thumping heart of sport at its best.

Which is to say, these are gritty, grimy, grim athletes flying by the seat of their pants (and their computers' pants) as they make a thousand battlefield decisions in 3 1/2 hours of combat.

Also, in the fashion of true sport from Little League to the corporate boardroom, every sailor goes to bed certain that someone on the other side is awake and drilling holes in his boat.

Come Saturday, we Americans risk a winning streak that began when Abe Lincoln was a horseback lawyer. Liberty goes against Australia II in the deciding race of the America's Cup we first won in 1851. Once behind, 3-1, the Aussies have won the last two races easily.

The latest dockside rumor is that the Aussies won the fifth race by sabotage. While America slept, gossip goes, a commando (probably in a kangaroo disguise) slipped onto Liberty. Because a jiggered pressure gauge later gave our boys faulty information, they broke the mast, costing us the race.

No one from Liberty gives credence to the gossip. Nor do they listen to Australian suggestions that Liberty has illegal compartments holding water. The weight of such water would help the boat sail faster.

"Total bull," said John Marshall, a Liberty sailor.

Marshall contends that yachties would walk the bottom of the Atlantic before cheating to win. This is a good thing to believe. Maybe three people believe it.

Everyone else believes everyone else is up to no good. This is human nature as shaped by competition and demonstrated by Richard Nixon's enemies list. The gentleman figured everyone was out to get him because he damn well knew he was out to get them.

The British (imaginative rumors here) aimed a listening device at the Liberty dock. An American chase boat flying four antennae jammed Australia II's radio. Liberty can pull plugs in its compartmentalized innards to let trapped water slosh from side to side as needed.

Beyond suspicion and protestation, America's Cup races are contests fascinating on levels from physical to cerebral.

"We are professionals," said Marshall, who isn't paid to sail but is a sail manufacturer famous for America's Cup sailing, "and we are as good at our sport as Jimmy Connors is at his."

Liberty, like all 12-meter yachts, carries a crew of 11: the helmsman, navigator, tactician, mainsail trimmer, two grinders, two pitmen, two tailers and a bow man.

To work well, the crew acts precisely. Sails come down and go up quickly. When the boat turns, a sail boom swings across the deck, threatening anyone slow to duck. As the boat leans, crewmen must dash to the high edge and cling there as ballast, half out of the boat.

The bow man, "a gymnast" (to quote Marshall), must be able to climb the 90-foot mast to make repairs. The grinders are 220-pound strongmen cranking handles that turn cables tightening sails.

The helmsman, steering, is the boss making decisions in consultation with his tactician, navigator and mainsail trimmer, all working off knowledge gained by seat-of-the-pants experience and abetted with data gained from computers reporting boat and wind speed and direction.

"Your first decision, in what really is a chess game on the sea, is which side of the course to take," Marshall said.

The search is for the best wind, which leads to the second level of decisions as to how to best anticipate, or at least discover quickly, the shifts of wind that can decide a race winner in a minute's time.

This is done by sight (seeing wind upcourse as it changes the texture of the water); by sound (at its best, a sailboat literally hums), and by feel (the helmsman's hand on the wheel, the trimmer's hand on a sail, everyone's feet on a dying deck).

It is hard enough to find the best wind and stay in it. Conner lost the sixth race when, thinking he had the wind, he actually forced Australia II to take a course that proved to be a wind tunnel.

With the wind as an ally, the third level of decisions then involves controlling your opponent's boat. You stay between that boat and the eye of the wind. You make no turn unless he does and you make every turn he does. That way you're in the same wind always, and unless the other boat is much superior it can not pass you.

"But if he's one knot faster and running better into the wind," said Marshall, "there's not much you can do."

Marshall said this with an anxious smile, for those words, he knew, fairly described Australia II's work in this America's Cup. That work, unfortunately for Liberty, is not dockside rumor.