We are all captive to the romance of seafaring tales, the burble of a bow wave rolling off on itself, the symmetry of sails set like vertical wings against an azure sky. But life aboard a small boat at sea is often otherwise.

Far offshore waves can seem to be higher than mountains, and the plunge into a trough between them is like an out-of-control ride down a snowy slope in a house on skis. Nevertheless, sailors bear the romance of their obsession proudly and tend to keep secret how much of serious sailing is punishing and miserable. Not Kathryn Lasky Knight, who has sailed enough miles to preach the truth with certainty. Her journal entry on July 8, 1974, when she was halfway across the Atlantic in a 30-foot sailboat: "This trip is just as awful as I ever imagined."

I know what she meant. And so do other sailors, though they rarely speak of it. Even Knight admits to tempting daydreams of gourmet meals perking away atop a gimbaled stove as a setting sun fires a sky orange. But then her alarms go off. She and her husband -- having crossed the Atlantic twice and sailed in and around most of Western Europe, the Caribbean and the East Coast of America -- know better. She remembers quickly the realities, and tells her tales.

There is, for example, the tale of what she calls La Cote Bilge. The long-distance sailor's larder is a messy wet storage area beneath the cabin floorboards, from which the cook at sea extracts rusted, oily, dented cans that once had labels. Checking carefully for "bulges, punctures or seam separations," the hungry mate hopes for something as tempting as old canned ham and cloudy canned corn. A guest aboard the Knights' 30-foot ketch Leucothea, then off the coast of Norway, contemplated exactly that "dinner" once and remarked, "I never thought I'd get trichinosis and botulism in the same meal."

There are tales of other people met at sea, petty tyrants who like being captains, drunken and threatening French soldiers who appear on deck in the middle of the night, drifters whose inability to get along on shore with normal people leads them to the isolation of oceans, where they float from port to port, having little to offer except carping about high food prices.

There are tales, too, about weather, and not just the stormy stuff. After sailing through four straight days of smothering cold fog off the coast of Maine, Knight writes: "I experienced a kind of sensory deprivation that I had never known. I had never in my life felt so totally cut off. Trying to imagine there was a world beyond that contained within the thirty-foot dimensions of our ketch required an extraordinary effort of the will and imagination." Finally reaching safe harbor, she resolved never to sail again, a promise to herself penetrated by a night's sleep and sailor's forgetfulness.

No one, of course, held a gun to Knight's head and said, "Sail, or else." And it is partly the sensations and memories of the grand moments that keep her not too far from a teak deck: leisurely motoring across Europe from Holland to the Mediterranean via canals with the ever-present odor of real French bread permeating the cabin, or exploring delicate beaches on tiny coastal Maine islands.

Nevertheless, there were extenuating circumstances that got Knight into all this. First, her parents, ironically, gave the couple the sailboat as a wedding gift. Then there was a deal: while sitting in the copilot seat of a small Piper Cherokee airplane and staring at the gas gauge, Mrs. Knight agreed to cross the Atlantic in the wedding present if Mr. Knight would abandon flying. Such are the negotiations of terror, trading momentary high fear for the low continuous roll of anxiety.

One can blunder almost anywhere into this journal of adventures and meet with the author's striking sensations: from a wave that knocks her splat into the cabin floor, a "mammoth black shape as tall as the mizzenmast racing toward us" that "drops its black jaws into a death grin of white spikes," to an idyllic morning on the tiny Danish island of Anholt, "a watercolor world of pale green dune grass, a milky sea, and fragile blue sky. Figures bronze-and-biscuit color walked down a wide beach fringed with sand dunes on an upper ridge."

Nevertheless, the charm, grace and character of Knight's lyrical travelogue and stunning statement of adventure would not be enough for those who do not know a tiller from a tack, so there must be more. One senses the former Kathryn Lasky would not stoop to simple boat-book writing, no matter how elegant. She reaches beyond, to vulnerable autobiography and biography that chart the odyssey of a mixed marriage: a woman of Russian-Jewish heritage and a man who could trace ancestors to the Mayflower, she a nest-builder and he an adventurer, her writing and his filmmaking, a woman of style and a man of nature. There is nothing at all simple about either of them, especially her love-hate relationship with the sea and small boats.