A stiff breeze rips across the Potomac River, leaving a trail of whitecaps in its wake. As the small, flat-bottom boat rolls into a seesawing dip off the south shore of Cobb Island, crabber Joanne Chapman jostles for balance and grips a hooked stick, ready to snag the crab pot lines.

The bobbing plastic markers identifying Chapman's pots are strung out in a crooked line several hundred yards off the island. She and her son Chappy, 12, haven't fished their 15 pots for several days because of stormy weather and high seas. Chapman hopes to find them scrambling with Chesapeake blue claw crabs when they are hauled to the surface.

The first wire mesh pot pulled overboard has trapped seven good-sized jimmie (mature male) crabs. Their elegant, sapphire-blue claws snap at one another as they toss and turn on their way into the culling box. The square pot is baited with fresh fish and heaved back into the river.

"Pesty and fighting crabs are the best," Chapman says, as she leans over the boat and feeds out the muddy line hand-over-hand. "The feistier they are, the better eating they'll be."

Chapman is an expert on what makes a good crab. She's been eating, and catching, them for years.

"I love crabs so much I had to find a way to supply my own demand," she jokes from the front of the rocking boat. "I knew I couldn't break my habit of eating crabs, so I started going after them myself."

The river is swollen and quiet after three days of rain. A bleak gray sky threatens more rain, and except for one or two lonely gulls, the river off the south shore belongs to Chapman and Chappy.

"Sometimes when I don't see anyone out here except for ourselves, and the sky's overcast and the wind is kicking up," she says, half seriously, "I wonder if we're not half crazy doing what we do. But something inside me makes me keep coming out for more."

She fell in love with crabs, she explains, when she and her husband Charles (Chappy) Sr. first vacationed on Cobb Island 15 years ago. They began making the 90-minute drive from their Arlington home on most weekends to feast on steamed crabs, crabcake sandwiches and fried soft-shell crab.

When they decided 11 years ago to make the small southern Maryland island their permanent home, and Chapman suddenly had "all the crabs I ever wanted at my own back door," she switched to serious crabbing. She is one of the few women in Maryland licensed in her own name to crab, and she sells most of her catch to friends and neighbors.

"I started hauling lines and doing the pots when my husband or his uncle was sick or had to miss a day's run," she explains as she shakes loose a stubborn crab. "Before I knew it I was the one who couldn't wait to get out there each morning and check the pots."

Eventually, her husband's bad back prevented him from hauling pots or bending over the culling box, so Chapman opted to continue running the pots alone.

At first the old-time watermen who considered the bay and rivers a man's world "weren't exactly sure what a woman was doing out here crabbing by herself," she said. "I had to make sure they knew I wasn't going after their business. My few pots are nothing compared to the hundreds the seasoned crabbers fish. The old-timers never made it difficult for me, but it did take a while to win their confidence."

Chapman's been a familiar sight on Neale Sound and Potomac waters for the past 10 years. Chappy Jr. started captaining the boat four years ago when he was 8 and his mother decided she needed "company and muscle." The mother-son team spends about an hour a day fishing.

There is a sober side to the affable crabber, who waves from her boat to neighbors along the shore. Her father drowned in the Potomac River when she was 9, and ever since she has harbored a fear of the water, she says. She forced herself to take swimming lessons, but has never forgiven the river for what it stole from her.

"I often wonder what my father would think of his daughter the crabber, out on the river he drowned in, enjoying herself," she says. "It's ironic, isn't it? This river gives me so much after it took so much away."

The watermen, who have learned to read the river and understand its eccentric behavior, have shared a few tricks of their trade with Chapman. Cobb Island resident Dick Culver, who crabs more than 200 pots in the summer and switches to oystering in the winter, once showed Chapman how to read a crab's back skimmer to determine if it's a peeler crab, one that is about to shed its shell and become a mature soft-shell crab.

"Joanne's all right with me," Culver said one morning while fishing his row of pots. "She knows what she's doing and has fit in on the water."

As the last pot is emptied into the culling box, Chappy circles the boat about and points it toward home. The yellow-and-blue markers fade away in the mist, while below the muddy brown waters, freshly baited pots lure another catch.

Before Chapman docks her crabs, she culls them to check whether they adhere to the state's minimum size requirements. Any crab measuring under five inches tip-to-tip is thrown back "to do some growing up," Chapman says.

What appeared to be a decent morning's catch before the culling dwindles to a quarter bushel by the time the boat slows to the harbor's eight knots speed limit. The pile of jimmie and sookie (mature female) crabs are kept captive in a floating trap off the Chapmans' dock until the afternoon customers arrive.

"It could have been a better day, but crabbing's something you can't always count on," Chapman says as she moors the boat. "When the day's catch is gone there'll be a few left over for dinner; and when we eat these fellas tonight, it all comes back why crabbing is such great fun."