The early november morning has turned from cold to downright bitter. The north wind whistles ominously, and boulders of gray clouds glower above us. But the hail pounding the deck of the Martha Lewis isn’t ice—it’s a torrent of native Chesapeake oysters, pouring from the jaws of a rusty dredge to the scuffed floorboards in front of us. My fellow sailors and I, new hands on an old skipjack, have a single task: to tear through the muddy load, locate the biggest shells, and earn some profit for our passage.

A half-century ago, this icy excursion would have been an average day on the Martha Lewis. Since her launch in 1955, the 82-foot-long skipjack has navigated the oyster beds of the Chesapeake, probing reefs increasingly ravaged by overfishing, parasites, and disease. Now one of Maryland’s few remaining working skipjacks, she survives as a living museum operated by the Chesapeake Heritage Conservancy, as a classroom for estuarine studies and environmental exploration.

Each autumn, the conservancy offers a rare window on the gritty reality of the waterman’s existence: half a dozen day trips for adventurers eager to experience a working skipjack. Unique among other Martha Lewis excursions, which also include educational tours for kids, Mother’s Day tea cruises, and “Margaritaville” sunset tours, the Discovery Dredge sails give participants a real-life lesson on how oysters are harvested from the Bay. The daunting list of passenger instructions—“Bring boots, brimmed and cold-weather hats, heavy-duty rain gear, gloves, and a change of clothes” —is our first hint that our day on the water might be more blue collar than bucolic.

We board the Martha lewis at Markel’s Boat Yard in South Baltimore (her permanent berth is in Havre de Grace) and find a knot of staffers prodding the motor that would pull the dredges from the water. With coaxing from Capt. Greg Shinn, volunteer crewman Gary High and executive director Cindi Beane, the engine eventually sputters and manages a phlegmy roar. Shinn slams the cover, bounds toward the ship’s wheel, and gives the order to cast off. Our destination is Seven Foot Knoll, a licensed oyster bed just a few miles east of Baltimore’s Inner Harbor.

Beane, now in her 10th year with the Chesapeake Heritage Conservancy, remarks that Martha Lewis passengers always praise the flavor of the fresh-from-the-Bay catch. “You can’t get a better tasting oyster,” she affirms, and announces to applause that there will be hot oyster stew for all hands at lunch—and two dozen oysters for each of us to take home at the end of the day.

When we reach the Patapsco River, the crew hoists Martha’s mighty 65-foot-tall sail. As regulations stipulate, we will be taking our oyster catch under wind power alone, without any on-board propulsion. The expanse of canvas looks several centuries out of place against the industrial bulk of Sparrows Point, which looms darkly on the horizon.

Shinn directs our group of six below deck, where bins overflow with waterproof overalls, rubberized work gloves, and kneepads. Kneepads? “You’ll want those when you’re kneeling,” he advises. “Those oyster shells are sharp.”

The Martha Lewis takes in nine or 10 bushels during an average Discovery Dredge trip. Some go to restaurants in Havre de Grace for $70 each, to support the work of the conservancy. But catches are puny compared to those of experienced watermen, says High. “We worked all day once next to another skipjack,” he relates. “The day after, the captain asked me, ‘How’d you do yesterday?’ ‘Not bad,’ I said. ‘Nine bushels.’ ‘Well, you tried,’ he replied. Turned out they’d gotten 150.”

In the cabin, I yank on well-worn rain pants and gloves and waddle back to the main deck, where Shinn is explaining the operation of the two large rakes, or dredges, that would soon be lowered to the Bay bottom.

The 5-foot-wide dredges, one on each side of the boat, drag the bottom as the skipjack moves across the reef, pushing the oysters into an attached rope basket. After a brief pass, the motorized winch raises the rake and basket, which opens, dumping the contents on the deck. That’s our cue. With our culling tools—rusty iron pokers with prongs at the 3-inch mark, the minimum size at which oysters can be harvested—we are to attack the heap, quickly sorting the largest oysters into bushel baskets and piling discards to be pushed back into the Bay.

“Remember—keep away from the ropes!” Shinn calls as the first haul emerges from the water. The jaws open, disgorging gallons of icy water and a load of blackened bivalves, which hit the deck like a fusillade.

The grimy pile is a far cry from restaurant oysters. These are rough hunks the size of bowling balls, studded with mussels, mud crabs, blennies, and other residents of the reef. We kneel down and dig in, hacking the clumps into single oysters. “Just scrape off the big stuff,” High urges. I quickly discover that most of the catch falls far short of the 3-inch minimum, and toss the rejects in the direction of Liz and Joelle, fellow watermen wannabes, who shovel them overboard. On the starboard side, another team is doing the same.

Within minutes, we’ve culled a dozen keepers from that first mountain of shell. They fill barely a quarter of a bushel basket. The rakes swing out and disappear into the waves for the next haul. Panting, we brush the muck from our gloves, wipe our dripping noses, and smile at each other with a shared realization: This is one tough way to make a living.

Writer Carol Denny will never swallow another oyster without an appreciation for the hard, cold effort it took to bring it to her plate.