On a Jet Ski, Falling Means That You Must Be Having Fun : The outing teaches that speed, although initially feared, actually keeps you up and going. Standing, though, is another matter.

Blind prejudice is a sad thing. Educated prejudice, on the other hand, is a handy survival skill--allowing you to avoid such unpleasantries as chain letters, insurance salespeople and fruitcake. To grasp the obvious is to avoid the painful.

You have observed a few facts about Jet Skis, namely that they make a lot of noise and blow a lot of smoke. They also go fast. Your average recreational model can hit speeds of 40 m.p.h.; soupier versions can send your cheeks scurrying behind your neck. Such speeds are fine when enjoyed from the comfort of a pressurized cabin with a bag of peanuts at hand, but not so good when the only thing that separates you from impact is your reflexes and the skin on your back.

This may explain why it’s hard to rent Jet Skis. Impossible, actually. You call the only Jet Ski rental place in town. The owner, named Howdy, tells you a few things, most notably that he no longer rents the things.

“Too much liability involved,” says Howdy, who will soon take his moniker and a like greeting to another, less regulated state. “I’m closing down and getting out of here.”

Your neighbor Scott is less concerned with potential litigation. An affable fellow and avid Jet Skier, Scott has offered to take you any time, an offer you’ve always declined, wise cowardice reinforced each time Scott slaps you on the back and says things like, “Once you feel the power, you’ll want to go as fast as you can.” You don’t believe in rushing into things. Jet Skis are barely 20 years old--Kawasaki sold its first model in 1974. This is not nearly enough time, you think, to iron out potential kinks or to clear things with Ralph Nader.

Eventually, curiosity and shame get the best of you. Scott is enthusiastic; perhaps in his eagerness, he has overlooked the potential headaches of supporting a second family.

“Awesome,” he says, clapping you on the back. “You’ll love it.”

And so the next day you find yourself standing in waist-deep water while Scott goes over the basics.

“Start button, stop button,” says Scott, pointing to the appropriate green and red buttons. “The throttle’s right here, just below the handlebar. It’s just like a motorcycle.”

Let him think what he wants, but if motorcycles were meant to be ridden on water, Sean Connery wouldn’t have had stuntmen.

You have one primary concern. Where’s the brake?

There isn’t one. There are three sure-fire ways to stop a Jet Ski: fall, press the stop button or intersect any unyielding object. Given the dynamics of forward momentum, pressing the stop button at 30 m.p.h. isn’t much different from hitting an immovable object--only the object you’ll be impaled upon will be the handlebars.

That leaves falling, which Scott assures you is tremendous fun. You will be buoyed by a wet suit and life vest and, if you’re going fast enough, says Scott, you’ll skim across the surface like a flat stone.

“You’ll just plane on the water. It’s great. If you’re not falling, you’re not having fun.”

Already you know this will be a guaranteed good time.

“What about the propeller?” you ask, knowing that falling means clambering back on board over the rear end.

Actually, a Jet Ski’s propeller is set well back underneath the machine. Churning furiously, the prop drives water down a narrow cylinder where it emerges in a powerful burst. This propels the Jet Ski. It can also give the poorly positioned rider a lively jolt.

Scott offers a last word of encouragement before you push off. “It’s like most other things,” he says. “Once you do it a time or two, it’s easy. Of course, it would be a lot easier in a river without waves and chop. Plus, typically, you don’t have big fishing boats coming in and out.”

Scott has chosen to take you to Ventura Harbor. It’s a weekend morning, and things are hopping.

Scott’s Jet Ski is a smaller version of the deluxe models you see in magazine ads, ads that show neatly coiffed families whooping it up while comfortably ensconced on seats that could accommodate Roseanne Arnold. The rear portion of Scott’s Jet Ski allows just enough room to stand or kneel. Kneeling seems an appropriate position given your vague sense of terror.

Just before you juice the throttle, Scott, perhaps sensing your anxiety, informs you that his Jet Ski has one other essential feature.

“It’s insured,” he says.

Getting to where you’re going--an expanse of sheltered water nestled behind a protective breakwater--means cutting directly across the harbor mouth and rush-hour boat traffic. Fine, if you could juice the throttle and roar across in a blink. Unfortunately, you have to obey the speed limit.

For the uninitiated, driving a Jet Ski at 5 m.p.h. is a bit like walking a high wire using a sack of bricks for balance. The Jet Ski lists wildly from side to side, not helped in its forward progress by your mad jerks on the handlebars. You make it across, but not before quickening the pulse rate of at least one charter boat captain.

Jet skiing is actually easier with speed, something Scott had harped on incessantly.

“When you feel like you’re going to fall, give it more gas,” he says, advice that at the time had seemed like encouraging a potential suicide to climb a bridge and balance on one foot. “Speed will keep you up and going.”

This proves true. Juicing the throttle smoothes out the wobbles. Plus the speed is, well, fun. The wind tears at your face. The water shoots beneath you like freshly Zambonied ice, blurring past in a gray rush. The sensation is mildly hypnotic, until you bury the nose of the Jet Ski and go arcing over the handlebars. But getting back in is easy, too--realizing that very few people can swim 30 m.p.h., Jet Ski manufacturers have designed the machines to slow instantly then circle back to you like a chastened mechanical dog.

After a time, other Jet Skiers show up. They carve graceful, sliding arcs at full throttle, leap each others’ wakes and generally whip their machines about with the casual elan of shoppers negotiating a supermarket aisle. Emboldened by these displays, you begin to dabble in your own feats of derring-do. Getting off your knees, for example.

That’s when you discover that standing on a Jet Ski is a lot more difficult than kneeling on one. Standing raises your center of gravity, making you more vulnerable to every bump and buck.

Speed, too, becomes doubly important; without lots of it, you simply totter over sideways like a drunk leaning for a wall that isn’t there. With lots of throttle you fall, too, the added speed lending more zest to your impact. Each time you hit the water, you drive enough saltwater up your nose to start your own desalination plant.

You fall hard and often, a display of self-flagellation that isn’t missed by Scott and his family, who are watching from the beach. Still, when you pull back to the beach, Scott thumps you on the back and congratulates you on your performance, a shameless display of lying that you attribute to good manners and profound relief.

Scott’s son Zack is more honest. Like most 5-year-olds, Zack is unschooled in the adult art of noise and smoke.

“You were riding the Jet Ski,” says Zack.

“Just like your dad.”

“Yeah, but you were falling.”

Child-abuse laws being what they are, you decide to let this pass.

Like most little ones, Zack is also keenly observant. He looks up at you and smiles.

“Still, you had fun, huh?”