Illness as the Open Sea : SAILING<i> by Susan Kenney (Viking: $18.95; 318 pp.)</i>

Subjects find their writers. Given the chance to choose, who would pick the devastating illness of a husband or wife as a theme, then write about it as if the creative process could somehow halt the destructive one? As if a life could depend upon turning anguish and suffering into art? Kenney, whose earlier book, “In Another Country,” confronted the emotional turmoil of a woman facing the possibility that her husband may die of a potentially fatal kidney disorder, has not been released by that relentless topic.

At the beginning of “Sailing,” Phil Boyd has recovered from the surgery that almost killed him, but his symptoms have recurred with a vengeance, forcing a sequel. “Sailing” is about survival; the title functioning on multiple levels.

A sailor in the most literal sense, Phil Boyd spends virtually all of his time on the sloop that his wife buys in the autumn after his disease has reappeared. The sea is his ally and his adversary, offering the possibility of life and the ever present reminder of death in a metaphor as fundamental as language itself. The entire book rests upon this analogy; extended to the utmost by a writer whose knowledge of both sailing and the disease in question has become encyclopedic.

The vocabulary of seamanship lends itself easily and naturally to her purpose; reefs, shoals, depths, shallows, tides and the vagaries of weather standing in for the fluctuations of illness; the lines, tiller, rudder and sails themselves signifying connection to the haven of normalcy.

There are adolescent children in the book, a dog; Phil’s university professorship, Sara’s sculpture; friends and family, even flashbacks to other happier days, but somehow these external realities all seem incidental; overwhelmed by the central image. Adept as she is at creating domestic scenes, Kenney has little time to spare for them here. The secondary characters can pull us back to the everyday world for a page or two, but that’s not the world in which Sara and Phil now live. Theirs is a surreal hell of scans and tests, of experimental treatments, of X-rays that show him his body as if it already lay beneath the sea. As the doctor points out trouble spots, Phil sees “knobs of coral, through the ribs of sunken ships, into the sea of darkness, where the shadows lie.”

The Boyds fly from their house in Maine to a hospital in Michigan; commute by car to another in Boston. Deliberately repetitious, the various hospital stays are interspersed among the sailing adventures; both the sea and technology holding out the promise of life even as they threaten death. Phil wonders if it would be better “to sail closer to the wind to gain distance at the expense of speed, or lay off to gain the fastest point of sail.” Shall he strive for the extension of life or the quality of life? These aren’t easy questions, and “Sailing” isn’t a diversion for the squeamish.

It is, however, a tour de force by an extravagantly gifted writer who simply does not have the luxury of plucking an appealing plot off the shelf. Those who have read Kenney’s two urbane mystery novels know that she can be versatile and inventive when given the chance. Even here, as she re-creates Phil’s post-surgery hallucinations of watching his entire life as if it were a home movie, the ingenuity shines through the tired convention. Stretched to the breaking point, the sailing metaphor also functions to underline the increasing distance opening between Sara and Phil, separating health from illness as the shore is separated from the sea.

Though Sara herself was once a competitive sailor who raced on the New England lakes and introduced Phil to the sport, by the time this book begins, she can hardly bear to step aboard the boat. Sailing has become Phil’s exclusive province, as impossible to share as his physical pain or his mental state.

When at last he tells Sara he plans to sail alone across the Atlantic in the 26-foot sloop, she is prepared for the announcement. The entire book has been building inexorably to that moment; to packing, provisioning, checking equipment and supplies, to the tacit agreement that this “lone and dangerous voyage” is the best possible solution. “Bad luck, he’d told her, to watch a boat out of sight.” His family files obediently up the gangway, his daughter risking one last wave of the hand; Sara and his son keeping their eyes straight ahead, and this time, bad luck behaves in accord with the venerable lore of the sea.