THE FIRST TIME I chartered a sailboat on the Chesapeake, years ago, the boat owner warned me about the Bay's legendary summer squalls. The only knockdown he'd experienced in 20 years of worldwide sailing, he said, had occurred on the Bay.

His 40-foot ketch had been slapped flat on the water by a 50-knot thunderstorm that was on him before he knew it. The mainsail wasn't even up at the time.

Then another friend told me of a Bay squall that caught his Bristol 32 with sails down but the jib loosely furled on the foredeck. The first gust, perhaps 60 knots, ripped loose the jib, ran it up the forestay and shredded it, all in about 15 seconds.

So one June Sunday when the heat began to build and the sky turned coppery, I prided myself on a seasoned Bay-sailor's prudence. I kept an eye on the clouds, monitored the VHF weather forecasts and warned the crew to be prepared to drop sails in a hurry.

But the weekend, a sendoff for my younger daughter after her college graduation, had been idyllic. We had ghosted our chartered Sabre 30 away from anchor in a leafy creek off the Wye River on Maryland's Eastern Shore that morning with scarcely a whisper, and we had a dilettante's fancy to pass the whole day without the sound of the engine.

So as we rounded Bloody Point light and started across the Bay we stayed with the wind, one eye on the sky and another on boats heading, as we were, for the entrance to the West River. When their sails dropped, so would ours.

The weatherman had forecast scattered thundershowers, and about 3:30 p.m. he issued a special alert for a fast-moving storm cell west of us on the Potomac above Colonial Beach. The small but violent low-pressure area, packing 50-knot winds and torrential rains, was moving north at about 45 knots.

If it changed direction and made for us, I felt certain, it would have to sweep in from the west. We were sailing with a southerly wind. The clouds were moving north; I told the crew to tell me if they changed course.

Aboard with my daughter Weeks and me that weekend were her future husband, Tetsu Kimura, 25, a wiry former All-America college soccer player from Japan, and Hillary Towsey, 30, a slender, globe-trotting family friend originally from Zimbabwe. Weeks and Tetsu had sailed little, Hillary a fair amount. I'd crewed offshore through gales off Cuba and Cape Fear, but none of us knew Chesapeake storms by anything but reputation.

Running northward in hazy sunshine with a weakening breeze, we watched the dark clouds to the west paralleling our course, preceded to the northeast by a white band of rain gradually blotting the Bay bridge from view. We debated dropping sails and starting the engine but decided against it. The weather didn't appear to be getting any closer.

Then, as we passed the shoals off Curtis Point and turned homeward into the West River for Galesville, I noticed a blue 28-foot sloop just north of us dropping its mainsail. It appeared to be a routine measure, leisurely performed. But then I saw the band of rain to the northeast. At least a mile inland moments before, it was now 300 yards away at the shoreline, speeding silently down on us even as the windvane atop the mast oscillated idly, uncertain of the breeze.

I thrust the wheel at Hillary and raced to the foredeck to drop the big genoa, shouting at her to start the engine and head into the storm. I got the sail down before the first gust slammed into us, whipping the bow around, and heeling the boat sharply to port.

My hollered instructions were lost in the wind and we continued lurching out of control, broadside to the squall and its rapidly mounting seas. Hillary hadn't the strength to handle the wheel, I realized, and Tetsu and Weeks hadn't the knowledge.

Clambering back over the pitching deck as Hillary got the engine started, I sent Tetsu and Weeks forward to unhank the jib and stuff it down the hatch. Hillary leaped to the cabin top and somehow dropped the mainsail, bracing herself against the boom and resourcefully lashing down the flogging Dacron with the first line that came to hand: the tail of the main halyard.

Tetsu and Weeks had the jib off and down the hatch in moments. Everyone was back in the cockpit before the heart of the squall screamed into us.

The rain roared down like hailstones as I fought with the wheel, wondering how fast I could motor safely into the steepening seas. Visibility was now a matter of yards. I was vaguely conscious of two other boats pitching and rolling within our sharply restricted field of vision. Hillary started asking about life jackets.

I told her they were under the port-quarter berth but not to worry. We were in the river and I knew the worst that could happen to us was to be blown onto a muddy shoal. But I was no longer positive where those shoals were. Or what would happen when we struck.

Then a gust I know was at least 50 knots (it blew the tops off seas now up to three feet) whipped us once again broadside to the storm. The boat heeled to port, its bare mast almost parallel to the water.

"Uh, Ken . . . " shouted Hillary, frantically tying on a life jacket.

Weeks and Tetsu peered down from the companionway, gone bugeyed at the waves suddenly snatching at the port lifelines, inches away.

"Dad?" yelled Weeks.

"Don't worry!" I shouted, trying to sound cheerful. "Once the bow's in the wind she'll be fine."

I gunned the engine with the wheel hard to starboard, and gradually she came around and righted on her keel, her bow smashing into the seas. I drove for the windward shore, with no certainty how far away it now was.

Spray washed over us again and again as we pounded into the squall, our way lit by lightning reflected off the white-capped waves. Gale-blown raindrops, flying almost horizontally, hammered at us like buckshot. A thunderclap exploded close astern, almost sending Hillary up the mast. It gradually grumbled away to the east. I was dimly aware that the rain was easing.

Then, through gray tendrils of cloud ahead, I saw the sky brightening.

And suddenly we were out of it, pitching through a wind-whipped mist and subsiding seas. Ahead of us the red channel marker miraculously appeared. We were right where we should have been, God only knows how. We'd come most of the distance sideways.

Behind us, a line of battered masts rolled drunkenly in the haze, hastily furled sails bunched below them like wet laundry. Everyone was still right side up. But the crews appeared shaky and pale.

"Bloody hell!" whooped Hillary. "We made it!" But from the radio below we heard distress calls.

The squall couldn't have lasted more than 20 minutes.

Later, reflective amid rum swizzles at dockside, we agreed as sailors have through the ages, that the preferred time to take in sail is before the storm. We had toyed with danger on a whim: because we didn't want the sound of the engine. I'll never do that again. As it turned out, the sound of that engine starting was the happiest we heard all weekend.

But the truth is we were probably as well prepared as most boats around us, if not better, and appeared to drop sail quicker. The suddenness of the wind shift and the speed and force of the storm were simply greater than any of us could have believed, regardless of warnings.

And we had the protection of a windward shore nearby. What if we'd been hit in mid-Bay?

"The usual procedure," a wry Chesapeake veteran told me later, "is to lose a jib sheet overboard and have it wrap around the prop, stalling the engine. Then you're really busy. It's the only proper way to ride out a squall on the Bay."