LOOKING FOR A SHIP By John McPhee Farrar Straus Giroux. 242 pp. $18.95

AT THE beginning of John McPhee's Looking for a Ship, Andy Chase, a personable young second mate from the state of Maine, is anxiously doing exactly what the book's title proclaims. He has been doing it, moreover, for 10 1/2 months, looking and waiting for a shipboard position at union halls from Boston to Charleston, S.C. At the end of the book the S.S. Stella Lykes, the ship he eventually finds, is dead adrift in deep Pacific swells off the west coast of South America. Down in the engine room engineers frantically work over valves and pumps in 150-degree heat. Unknown to them the Stella Lykes, an American-flag freighter converted to container carrying, has a crack in her hull. Sea water is seeping into her diesel fuel.

With every page in between in this remarkably adroit and compelling book, a hard message is forming in the reader's mind. McPhee does not trumpet the message, nor explore it in any depth. Rather, it comes across in a masterful accumulation of everyday events aboard the Stella Lykes and in the thoughts and experiences of her crew. Andy Chase, for example, has looked and waited so long for the Stella because the Masters, Mates and Pilots Union, well aware of the scarcity of jobs it helped to create, has invented a diabolical system of forced time ashore and poker-game hiring to parcel out the few berths available on American bottoms. (Briefly, every member has a card bearing the exact day, hour and minute he signed off his last ship. To get another he must be present at a union office when a sailing is first posted and show a "killer card" certifying a longer time ashore than anyone else in the room. The competition, in fact, sometimes comes down to hours and minutes.) The Stella Lykes breaks down bound home from South America because she is an aging queen. Built in 1964, she has been through three owners and a stretching amidships of 115 feet to accommodate more container cargo. Her captain calls her a good ship, built of good American steel, but treats her very gently, literally coaxing her along with soliloquies from the bridge. "I talk things over with her and almost ask her, 'Hey, can we do this?' " he readily admits. Or sometimes: "Look, old girl, you're in trouble. Let's see if we can help each other."

The message, the reader will now understand, is that the American merchant marine has hit new lows. The Stella Lykes is one of only 10 Lykes Brothers container ships; the Lykes Brothers Steamship Company is one of the United States' last three major international merchant shipping companies flying the American flag. No new merchant ships are currently on the ways in American shipyards. Again, hear the captain: "Russia is going to have five thousand merchant ships in ten years. And we are going to have none -- enn,oh,enn,ee -- as in not any."

Looking for a Ship holds many surprises, even for those who know something of the maritime world. Piracy, for one. Old fashioned shipboard-attack piracy, that is, which has become endemic in certain parts of the Third World. Or the huge sealed cargo containers labeled "Said to Contain 16,636 pounds of shower curtains, telephones, and wall clocks," or "Said to Contain panties de senora, five and a half tons." Shipping companies accept them as such, even though the owners know they are liable for the drugs or stowaways they may also contain. On a more comforting note, old timers will be glad to learn that prudent skippers relegate all the new electronic devices -- SatNav, Automatic Radar Plotting, Autopilots -- to a secondary role whenever they find themselves in tight spots. Threading through a fishing fleet at night or approaching a difficult harbor, the Stella's Captain Paul McHenry Washburn will rely more on bow lookouts and have his best helmsman at the wheel. SatNavs go out, and as Washburn likes to relate, there was once a ship that left Philadelphia for South America with a malfunctioning gyrocompass. It hit the south shore of Long Island before anyone on the bridge thought to check the standard magnetic compass. SOME SUBTLE changes in McPhee's prose style may also come as a surprise to his many admirers. (This reviewer, for whom McPhee has been a role model, unabashedly counts himself one.) A chapter begins: "Four A.M., 32.25 degrees south, sky overcast, an almost total darkness on the bridge. To all horizons, no light." Similar dot-and-dash phrasings appear elsewhere in the book, like entries from a ship's log. And the Stella Lykes's journey is blurred by inverted chronologies and a sense of timelessness, like shipboard life itself. Happily, too, McPhee occasionally breaks loose with a kink of breezy insouciance that is a long way from the tight control and customary detachment of New Yorker nonfiction. Take this passage, about a pirate attack near Guayaquil:

"Pirates have boarded the ship, evidently up the anchor chain and through the hawsepipe to the fo'c'sle deck. How many of them? Where are they now? Who knows?

"Understand: this ship is about the length of the Port Authority Bus Terminal, Rockefeller Center, Pennsylvania Station, Union Square. To berth her you need almost three city blocks. With her piled-high containers divided by canyons under the jumbo boom, she is if nothing else, labyrinthine. She carries a crew of thirty-four. Thirty-four highly trained SWAT troops would have a hard time defending Rockefeller Center, so what can be expected of a militia of aging gourds?"

But the strength of Looking for a Ship, as in so many of McPhee's 20 previous books, rests in the author's quick hand in gaining the trust of his subjects and bringing them fully alive with a remarkable economy of dialogue and description. On the Stella Lykes his subjects -- better, his friends -- are an especially likable and interesting lot. They range from Captain Washburn, who is a constant source of wisdom and peppery wit, to master helmsman Vernon McLaughlin of the Cayman Islands, who at age 58 has the best distance vision on the ship. "When I go ashore, after this trip, I'll be fluttering like a fish out of water," he says of his profession. "I'll want to get back. It's an evil you want to come back to."

The evil, if it is one, is more accurately described as an addiction, shared by many who go to sea. Outwardly, it takes the form of complaining about the discomforts, dangers or irregular employment of seafaring; inwardly, of returning to it, of signing on again and again. But, as so often in this book, Captain Washburn has the last word on the subject. "A couple of guys are here only for the money," he will say. "But there are a lot of us here because this is where we fit in, and we don't fit in anywhere else."

He has it right, I think. The pay in the American merchant marine is by all standards very high. (Captains and chief mates can make from $75,000 to $100,000 or more in good years; second cooks or engine-room hands, $30,000 to $40,000.) But that is only part of it. In the later stages of the addiction the place "where we fit in" is more than a mass of steel and throbbing engines. It becomes a refuge. And, in time, a home.

So sailors go back to their home. So, too, in a sense does John McPhee, who shipped out in his younger years with the now defunct Grace Line. That fact, even if it were not mentioned in the text, is apparent throughout this small, splendid and highly informed book. More than the geology of Appalachia and our western states, the subject of three of McPhee's recent works, the sea seems to be his natural home. I hope he will return to it, signing on again and again. William W. Warner is the author of "Beautiful Swimmers: Watermen, Crabs, and the Chesapeake Bay," which won the Pulitzer Prize for general nonfiction.