John Barth's ''Sabbatical'' is several novels disguised as one. It's a novel about sailing up the Chesapeake Bay. Charts, navigation. Tillers and mainsails. Mysterious islands. A sea monster. It's a novel about the CIA. Double agents, or moles. Missing persons. Foreign governments. Code names.
It's a novel about two people in love, he for the second time, she for the first. Fenwick, age 50 and Susan, age 35, together on their sailboat, the Pokey, named after Edgar Allen Poe and Francis Scott Key, famous alleged ancestors of Susan and Fenn.
It's a novel about an American family, one of those wacky, zestful mixed-up American families that appear in films. An earth-mother, Susan's mother, who runs a seafood restaurant and takes lovers. Susan's twin sister, Mim, who is raising two illegitimate children, the latest by her common-law husband Eastwood Ho, a Vietnamese oral poet. Two impossible children, one of whom bears the name Messiah, and the other of whom is christened Edgar Allen Ho.
It's a novel filled with literary antecedents: Homer, Conrad, Poe, Nabokov, Borges, Barth himself. ''Sabbatical'' is a novel about an odyssey, a night-sea journey involving a ''world-scarred rough and ready pragmatic hero'' - that's Fenwick - and his ''innocent academic sidekick'' - that's Susan.
There are storms at sea, a la Joseph Conrad, and perhaps a heart of darkness - that's the CIA. There's a mysterious disappearance and return, a kind of recirculation of the sea, out of Poe's ''Narrative of Arthur Gordon Pym.'' There are Nabokovian doubles, twins galore, double agents, doppelgangers, double dreams, mirror images, word-play like Poe-Key, Pokey, ''kepones,'' i.e., chemicals in the Chesapeake, polluting it, flash forward, ''fleshbecks,'' enough literary games to satisfy the most avid of crossword puzzle fans or detectives of the symbol-hunt. Gardens of forking paths (reminiscent of Jorge Luis Borges) where the letter Y symbolizes a fork in the road or the river, a place where three roads meet. There's a Wye Island, a Key Island, a Poe Cove.
And that's where the novel ends. Just about where it began. Like Joyce's ''Finnegan's Wake,'' only shorter. Mercifully.
Barth's own ''Floating Opera'' and ''Chimera'' also come to mind. This is Barth's claim to ownership of Chesapeake Bay, James Michener take notice. This is floating opera cum shipboard romance, or, Barth's words, ''paperback Gothic with a Hollywood tie-in.'' This is an amphibious novel of land and sea, a monster of sorts, a chimera, a plotless wonder, something like the ''legendary sea-monster that swims through our story,'' something with a ''thick neck tapering forward to a whiskerless head . . . no bill, beak, or snout, that we can see.'' And it's gone aground in Chesapeake Bay. Alas.