Bubbles From the Barthtub : THE LAST VOYAGE OF SOMEBODY THE SAILOR, <i> By John Barth (Little, Brown: $22.95; 573 pp.)</i>

John Barth’s been a while recovering from “Letters” (1979), and so have I. “Letters” was an endless epistolary novel in which characters from previous Barth fictions complained--in letters to their dead fathers, their unborn children, one another and themselves--about a lack of pattern in their imagined lives.

As if for some fresh air, Barth then left this library of self-reference, in a boat, to worry the tricky currents of “Sabbatical” and “Tidewater Tales.” He is back with a huge appetite. “The Last Voyage of Somebody the Sailor” is many boats and several libraries, not quite so long as “Letters,” and a lot more cheerful, but likewise an elephantiasis of narrative parts.

On the one narrative hand, “Somebody” is the 20th-Century American story of Simon William Behler, growing up during World War II on the eastern shore of Maryland, wanting to be a famous explorer, flying in a plane and, with poor doomed Daisy, discovering sex. For professional reasons in the 1960s, Simon Behler will change his name to Bill Baylor when he becomes a writer of science fiction and a New Journalist--”a merchandisable blend of candor and reticence, by a graphical fact and an imaginative projection.” He will marry Jane, and divorce her after she tries to drown him in the Virgin Islands. He will find Julia, a world-famous photographer and Daisy’s green-eyed younger sister, on his second trip to Moorish Spain. Off the coast of Sri Lanka, trying to reverse the last voyage of Sindbad the Sailor, they will drown.

Then again, maybe not.

On the other narrative hand, “Somebody” is the medieval Arabian story of Sindbad himself, tired and cranky after six voyages, telling the same old stories of floating islands and monstrous fish, serpents and diamonds, cannibals and apes. Sindbad tells these stories, in a weeklong series of suppers at his Baghdad digs, to the usual greedy merchants, sultry slave girls, imperial spies and a camel.

Also at the table, matching Sindbad story for story, is Bill Baylor, now called Bey al-Loor, who was picked up by one of Sindbad’s trawlers in the Persian Gulf, 1,500 miles from Sri Lanka and 1,000 years early for the New Journalism: “I was (and am),” he says, “not in charted space but in recorded time.”

He’s in neither, really. He’s in literature, in Sir Richard Burton’s translation of the “Arabian Nights.” We’re invited to think of Scheherazade as the first New Journalist.

In Baghdad, City of Peace, they don’t like Baylor’s stories as much as they like Sindbad’s. Says one merchant, who is also trying to cut a deal for Sindbad’s daughter Yasmin, who may or may not have been damaged by pirates, “Give me familiar, substantial stuff: rocs and rhinoceri, ifrits and flying carpets--Inshallah!--till our final swallow. Let no outlander imagine that such crazed fabrications as machines that mark the hour or roll themselves down the road will ever take the place of our homely Islamic realism, the very capital of narrative.” Besides: “A story without a moral is a meal without mint tea.”

Throughout “Somebody,” these two narratives shake hands, or are pumped on like a slide rule to play their logarithmic scales. The voyages of Sindbad and Baylor correspond, of course, in clever ways, with the same shipwrecks, the same subtext of incest and the same secret language of popped vowels and chewed consonants. But Sindbad is weary of all water. Rather than undertake a seventh trip, especially to Serendib, which you can’t get to anyway except by accident, he’d prefer to stay put in Baghdad, where he’s “drained his ponds and fountains, sanded his gardens, throttled his peafowl, cactused and cameled his courtyard.” Whereas Bill Baylor, like Bill Bailey, wants to come home. In return for a promise to write up his stories, Baylor talks Sindbad into sending him, with green-eyed Yasmin, to Serendib in the Sailor’s stead.

This much is clear: Baylor is drowning in stories; he needs to recover his own life. But what is life, as they must have said in old Baghdad, but a voyage unto death, which we put off by telling stories? We are all born in water, the first passage, and, after the usual strandings and bereavements, our memories go down the drain. There’s even a hint, in Barth’s account of Baylor’s affair with Julie Moore (“Jew-Moor”), of deadly cancer, genuine loss, real pain, obscured by literary flourish. Another sort of novel might be submerged in these waters. A third, too, is implicit in the chapters devoted to Simon Behler’s Tidewater boyhood.

But Barth disdains homely realism, Islamic or otherwise. He is fussy and knowing. His 20th Century is full of wicked winks at Portnoy, on masturbation; at “Tender Is the Night,” in case we missed the incest reference; at Vonnegut, Plimpton and Hunter S. Thompson, for sci-fi and the New Journalism; at John Updike, for a marriage on the rocks; at Paul Bowles for a one-night stand in Tangier; at Jorge Luis Borges, for the name of a sailing ship. So elaborate is one joke about cleansers like Bon Ami and Bab-O that I started thinking of Bill Baylor as the Flying Dutchman. To prepare us for the long Arabian nights, everybody on Maryland’s eastern shore smokes Camels, and even the condom Daisy supplies to Simon is a Sheik instead of a Trojan.

I haven’t even mentioned the wristwatch with, of course, Arabic numerals. Nor the identification bracelet without, of course, a name engraved. And why, oh why, must Daisy, for her generosity, be punished with madness?

As for his bygone Orient, it’s exactly the kind of wet dream that drives Edward Said crazy, a cartoon of muezzins (saying “Wombat! Wombat!”) and minarets (handy phallic symbols); of turbans and djellabas, carpets and belly dancers, hookahs and hammocks, scimitars and souks, hashish and goat-bleat, mindless greed and kinky sex. Part of this doubtless Richard Burton’s fault, and part of it Rudolph Valentino’s, and part of it Barth’s, who goes in for a bouncy sort of pidgin-Arabic that makes the teeth grind even as we’re grinning at these jokes. But the result, in spite of some wonderful scenes, is an odd amalgam of paperback bodice-ripper and Gilbert & Sullivan’s “Mikado.” Poor little Buttercup. Or Daisy. Or Yasmin.

I know I’m not having as much fun as John Barth did. But Scheherazade and the “Arabian Nights” have been borrowed recently for more substantial and horrific fiction, by David Grossman in “Sea: Under Love” and by Salman Rushdie in “The Satanic Verses” and “Haroun and the Sea of Stories.” And Gunter Grass has taken on Grimm fairy tales, for a savage moral purpose, in “The Flounder” and “The Rat.”

Just why is it that when our home-grown postmodernists go in for a revisionist rewriting of the earliest narratives--like Barth with Sindbad, like Barthelme with Snow White, like Coover with Pinocchio--they are comedians, thumbing their noses and slapping their sticks?