Ionthe (Yonty) Rhodes, a 54-year-old grandmother from Virginia's rural, impoverished Eastern Shore, got up sometime before the sun and the sea gulls yesterday morning and boarded a small fishing boat with her family and a few friends. Without fanfare, she lowered herself into the four-foot swells at the mouth of the Chesapeake Bay and spent the next 11 hours swimming.

Stroking steadily in an eastward arc of about 18 miles, always within sight of two small boats bearing family and friends, Rhodes made the Virginia Beach shore at 6:10 p.m., apparently becoming the first person to swim solo through the swift-moving waters where the Chesapeake empties into the Atlantic.

Borne east into the ocean by the morning's ebb tide, and then slightly westward by the afternoon flood tide, Rhodes came ashore at the northern end of Virginia Beach's Atlantic shoreline, two miles south of her planned landing at Cape Henry. "I was never worried," she huffed as she clambered up the beach and rubbed her salt-encrusted eyes. "Well, I'm glad it's over," said her 8-year-old daughter, Adria.

Rhodes, who made the swim for a local charity, persevered despite jellyfish (she was twice stung), stingrays (twice sighted), the possibility of sharks (a 260-pounder caught in those waters just last week), winds, waves and boredom.

What did she think about with only channel buoys to break the horizon? "I thought about this," said Rhodes, digging her foot into the dry sand. "And I thought about nothing."

According to Eastern Shore old-timers, the only person known to have considered swimming the mouth of the bay was a fisherman named John Half. He accepted a dare in the '50s, but never actually started the swim.

That decision probably earned him more respect than disdain, judging by the respect bay fisherman continue to accord the swift-moving, dangerous waters around the 17.6-mile-long bridge-tunnel that connects the shore with Virginia Beach. "That's dirty, dangerous waters," said George Etz, who has been working the waters off Cape Charles for nearly two decades. "You got all those rivers -- the James, the York, the Elizabeth, the Susquehanna -- they're all pouring down through there. And you got sharks, too. I give her credit. You won't find me trying to swim across the bay, no."

Saturday's seas were so rough, according to the captain of the Virginia Beach lifeguard patrol, that danger signs were posted along the shore and swimmers were allowed to go only waist-deep into the water. "Yesterday the surf was rolling, there was a lot of chop," said Edward (Ned) Kuehn. Somebody in good shape can do sidestroke just about forever; it's much easier than overhand crawl. But she had the waves, and the salt water."

The currents were swiftest yesterday in the Thimble Shoal Channel, the usual passage for large ocean tankers headed for Hampton Roads. Rhodes was swept several miles off course there, as she swam without progress amidst the looming black hulls. "Where's this crazy lady swimming the channel?" asked one pilot over a marine radio circuit. "Keep her clear, now, I don't want to run into her."

It was late afternoon by then; the strong wind had delayed the flood tide slightly and though the water temperature had risen to 75, Rhodes was beginning to complain of cold. "That's exhaustion more than anything else," said Basil (Dusty) Rhodes, her husband and chairman of the Northampton Red Cross Chapter that was to benefit from pledges made during the swim.

Along with neighboring Accomack, Northampton County is one of the poorest counties in Virginia, with an average annual income of $6,000 and an unemployment rate at a steady 14 percent. Large farms, a few packing plants and the bridge-tunnel are the major employers. The Northampton Red Cross is virtually bankrupt. Rhodes and three of her children swam the same course last year in a relay and raised over $1,000.

The solo swim was supposed to make people dig deeper into their pockets. But as of today the effort had raised only $370. "If I had had any idea that this was all we would raise, I would never have done it," she said. "When you consider how much so many people put to help the swim , it just couldn't begin to compensate."

As she swam yesterday, her husband perched anxiously on the bow of a patrol boat and watched his wife 20 feet away. "I'm thinking about her safety," said Rhodes, who had vetoed his wife's plans to make the same swim last year.

The swim had attracted more attention this year, but it wasn't simply a worthy cause that heightened interest in the swim, he said. "No, it's like a bullfight. There's a chance she'll drown, and people know that."

In an era of sophisticated supersportsmanship, Rhodes' style was iconoclastic. There were no trainers, no special diet for the short, stocky Red Cross water instructor. Not even a bathing cap for her head. "I don't own one," she said. To get in shape she swam a mile or two each day in a 32-foot pool that she cleaned before her daily swimming classes.

Rhodes got only five hours' sleep the night before her swim. She made lunches for her family and had no time to eat breakfast before leaving the house. She ate only four candy bars and two lemonades during the swim.

On Friday night the weatherman had predicted northeast wind and sloppy water, and at impromptu press conference at Etz's ("Famous Crab Salad") Restaurant in Cape Charles, many county residents -- and not a few skeptics -- gathered to wish her well. "I think she's crazy," said waitress Margaret Ulrich. "But I hope she makes it."

"I don't think she'll make it, but she's determined " said one waterman. "She's stubborn," said her husband. "When she wants to do something, she does it."

"My only comment is you ought to put some liniment on," he said in the tone of voice used for giving advice to be ignored. "I've been in a swimming pool with chlorine all summer," replied Rhodes. "All I'm going to do is take off my watch, because it looks too much like a Hopkins lure, and tape on my rings."

Rhodes began her swim about a half-mile out from a mosquito-ridden sand flat off a Cape Charles inlet. Shortly before 7 a.m., within sight of the bridge-tunnel, she jumped in and began her swim with her 16-year-old daughter, Ilia. The water was a chilly 69 degrees, the wind from the northwest at about 15 knots.

By afternoon Rhodes was swimming alone, Ilia having been felled by leg cramps. Rhodes sidestroked implacably, the three-foot waves lifting her up and down, hiding her close-shorn head, then lifting her high. "That's exhaustion," said her husband.

"Watch out! There are lots of gulls here -- they are feeding on something," she called to her husband at about 5, as the condominiums on the Virginia Beach oceanfront poked through the haze. "They're feeding on something. And if they're feeding, something else is too!"

"That's porpoise," her husband said as a school raced beyond Rhodes in their powerful arabesques. "Oh, porpoise, that's all right."

"Why don't you hitch a ride?" her daughter called out. There was no reply.

By 5:30, the buildings on the shore were well defined. "Can you see people?" Rhodes asked, no longer smiling, her eyes slits. "Can you see people?" she called again. Yes, people were visible. "Oh, thank God," said Rhodes. "We're only a half-mile from shore."