The American frontier continues to be a well from which writers draw wonderful tales, tall and otherwise. Undeterred by Frederick Jackson Turner's thesis that the frontier closed when the West was settled, journalists have found half a dozen new frontiers in recent years--outer space, inner space, poverty, the "energy frontier." No matter how ugly or even boring the frontier of their choice may be on the surface, it is never less than new, never less than challenging. The best frontier explorers, from Mark Twain in "Roughing It" to John McPhee in "Coming Into the Country," generally begin their journeys with romantic adventure in their hearts, yet return with notebooks full of disillusioning reality.

So it is with these two books. Each has as its setting the energy frontier. Each is about "oil field trash," colorful heirs to the legacy of cowboys and mountain men. The resemblance between "Going Overboard" and "Roughnecking It," however, ends there.

Chilton Williamson, in time-honored tradition, spent a year in the West's latest boom town region, the Overthrust Belt of Wyoming. He parked his pickup alongside those of roustabouts, drillers and their families in a beery, soon-to-be-seedy dump called the Ritz Apartments, in Kemmerer, a town that could easily have existed in the Gold Rush days a century earlier.

Keeping his profile low and his gun loaded, Williamson describes the daily grind behind the energy frontier myth. His best friend, Sam Slade, is a derrick hand who has uprooted his wife and three children from upstate New York temporarily to seek his fortune, or at least $40,000 per year. Williamson makes few judgments about behavior on this bleak prairie. Rather he describes, with a novelist's flair for detail and dialogue, how Slade and crew risk their necks on their rig digging for black gold, then how they fill their time off with purposeless, joyless fightin' and drinkin' and shootin' and pukin'.

Inside the derrick at Banfield 20, for example, 95 feet above the drilling floor, Sam one night performs a terrifying high-wire act without a safety belt in order to latch some balky pipe fittings. Williamson is properly impressed. Then when deer season arrives, the Slade bunch tears into the mountains in four-wheelers (modern cowboys' equivalent of horses), oversupplied with liquor and marijuana; their manly pursuit of game turns into something like a "Saturday Night Live" parody of hunting. Later, Sam is so frenzied on an elk hunt ("I ain't leavin Wyomin without gettin me an elk") that he nearly destroys a borrowed truck and finally kills a poor doe instead.

In the end, it is clear that the author sees Sam and company as gritty, likable slaves of the American Dream, just as their frontier forebears were. By the time Williamson rides away from the sunset to home back East, Sam has gotten his dream's worth--a promotion to driller and a double-wide trailer, which, in Kemmerer, passes for a luxurious home. A melancholy existence, perhaps, but ultra-American. Give Williamson credit for painting the grim oil boom town in harsh strokes, while still making us care about the funny, violent men and women who populate it.

Lucy Gwin also spent a year in and around an oil boom town, Morgan City, La. But whereas Williamson, almost immediately, by virtue of gender alone, became one of the boys, Gwin was never anything but an outsider, and a mighty threatening one, among the male "rigrats" and supply boat crews. "Going Overboard" begins as a vivid account of a gal on the offshore oil frontier, then grows into a truly riveting suspense tale when the author realizes she is confronting a far more difficult barrier--the frontier of sex roles.

Gwin skillfully weaves patches of her past as an advertising executive, restaurateur, Zen student and divorced mother of two into her main narrative. She is 35 years old at the outset of her adventure, running away from that past and from a male companion. She lands her first job as cook on a boat that carries supplies to offshore rigs. Cook is the lone job "allowed" women. Trouble is, Lucy falls in love--with the sea and seagoing. The job she covets is quintessentially masculine, that of deckhand. She is lucky enough to start off with an apparently benevolent Cajun captain who teaches her how to handle everything from wheelhouse to engine.

Her ambition sounds reasonable. "It didn't seem fair," she explains, "that when boys grow up they need never give up their toys. They could go on playing with bigger and better ones: workboats, cranes, forklifts, helicopters, while the girls stayed home, getting serious. What the men kept calling the Man's World, as if were some new variety of theme park, was just that: an amusement center for the terminally boyish and, in my case, the terminally tomboyish."

Unfortunately, every trait that endears Lucy to herself and to us--her passion, spunk, good humor, toughness--helps make her the biggest freak of all in this Man's World of crazed redneck slobs. She insists on proving, over and over, that she can handle any exhausting chore, from lassoeing high pilings with huge ropes to scrubbing an entire deck. In her own eyes, she is Wonder Woman: To her coworkers, who begin to turn against her, she is a "Morphadite" who doesn't realize a woman's place is literally barefoot and pregnant (as are the women attached to her boat mates).

The more adept she becomes, the angrier the entire coastal brotherhood gets, even though she succeeds in convincing us that she genuinely likes many of these grisly merchant marines. Before a year is up, she has been rejected by 12 captains, yet her personnel records, she learns later, show they have rated her a first-class sailor. Her report from the murky waters of what she labels Testosterone Culture includes one mate who climaxes a night of gross story-swapping by biting into a live black beetle, a captain who nearly capsizes his boat rather than turn back from a storm, and another captain who reads pornography aloud.

Without giving away the ending of "Going Overboard," I must note that Gwin comes close to losing her life after she despairingly files charges of sexual harassment against her tormentors. There is not a single hero in the book . . . but there certainly is a heroine. Lucy Gwin, as sassy and sure-handed at the typewriter as she is on deck, offers us a self-portrait of one helluva gutsy pioneer woman on the dangerous sexual frontier. "Going Overboard," in less capable hands, could have been a feminist tract. Instead, it is an unforgettable Southern horror story that calls to mind James Dickey's "Deliverance," and it's just as scary