SAN FRANCISCO -- This weekend, thousands will gather here on the waterfront. They will gaze at the bay. But they may be confused. They may be outright baffled.

"We do not understand," the thousands will say. "Are those actual boats out there, actually racing each other in the actual America's Cup? We thought there was only arguing. And cheating. And broken boats. And finger pointing. And uncompetitive competition. What is this 'sailing classic' of which people speak? Will we truly be seeing such a thing?"

Yes. They truly will. But you can't blame folks for their puzzlement. The last two months have pretty much been a salty procession of ascot-wearing whiners and an overhyped "Summer of Racing" that mostly went pffffffffffft. There was also human tragedy, when a Swedish boat's crew member perished in an accident.

At long last, however, the America's Cup has the chance to redeem itself and show us why we should pay attention. Saturday afternoon, the two most expensive multi-hulled racing watercraft ever constructed will begin a best-of-17 series of races by skimming at almost 50 miles per hour across the waves between the Golden Gate Bridge and Alcatraz Island in pursuit of sailing's oldest trophy.

"If that's not cool, I don't know what is," New Zealand sail trimmer Glen Ashby said the other day.

Aye. It should be a corker, as we swabbies like to say. The main event is here:

In this corner, ladies and gentlemen, we introduce the challenger: Emirates Team New Zealand, out to win a prize coveted so greatly by its homeland the federal government has contributed $36 million to the $100 million-plus effort.

And in the other corner, we introduce the defender: Oracle Team USA, financed privately by bearded Silicon Valley eminence Larry Ellison -- and under pressure to overcome a severe penalty assessed by the international jury for illegally tampering with its smaller boats in last year's preliminary races.

The situation led Oracle skipper Jimmy Spithill to declare his team a decided underdog earlier this week.

Oracle Team USA practices with their AC72’s in San Francisco Bay before the start of the semifinals of the Luis Vuitton Cup between Sweden and Italy
Oracle Team USA practices with their AC72's in San Francisco Bay before the start of the semifinals of the Luis Vuitton Cup between Sweden and Italy in San Francisco, Calif., on Tuesday, August 6, 2013. (Karl Mondon/Bay Area News Group)

"If there's ever a time that we need the people of San Francisco and the people of the USA, it's now," Spithill said at a media session. "It'll be critical. We want to keep the cup here. They don't. That's what is important to get into people's heads."

Well, you can decide for yourself if you want to care. There is a case to be made that it's pretty silly to feel any emotion for an event in which gazillionaires vie to become the toast of their yachting crowd by hiring mercenary sailors from all over the world -- there are only two Americans on the USA boat and Spithill is Australian -- to operate preposterously expensive high-tech craft that bear no relation to your dinghy boats. But the spectacle should be stunning to watch.

"If you're not fast enough, you're not fast enough," said Dean Barker, the Emirates Team New Zealand skipper. "And it's no more complicated than that."

But who's the real favorite to win? It still has to be the Oracle boat, despite Spithill's spin and the jury's severe spanking. Oracle Team USA will start the series down two races, meaning it must win 11 rather than nine to claim the trophy. Oracle is also without two important crew members, suspended by the international jury. So what? Ellison has such deep pockets, he was able to sign up a two-deep crew of the world's top-tier sailors -- sort of like an NFL team without a salary cap spending a bundle on not just the best players at their positions, but the second- and third-best.

Also, never forget this: Under America's Cup regulations, the defender is permitted to set the conditions of the competition. Ellison chose to race this series in ludicrously awesome 72-foot catamarans with 131-foot-tall "wing sails." If his team was unable to master the architecture that Ellison himself created -- and if the slimy cheating scandal derails them -- then shame on him and shame on them.

Usually, the America's Cup is no neck-and-neck competition. One boat tends to be superior out of the gate and then runs away with the trophy. So if Oracle Team USA can win nine races, it can win 11 races. But if New Zealand jumps out ahead Saturday and demonstrates it has superior equipment, the series could be over by next weekend. From this point, finally, it's up to the sailors and the sails.

"At the end of the day," Spithill said, "no matter what happens on the shore and with all the games that got played, to take that trophy, you've got to win on the water."

Ellison's obsessive mission -- to stage a spirited and entertaining America's Cup finals in which he triumphs on the bay that he loves -- can still be realized. But he's got just two more weeks to pull it off. A loss would be one of his greatest embarrassments. Curious eyes on the waterfront await.

Contact Mark Purdy at mpurdy@mercurynews.com. Follow him at Twitter.com/MercPurdy.