It is doubtful whether there actually was a woman on board Christopher Columbus's fabled fleet, but Mrs. Christopher Columbus, poetic wife of the Italian navigator, here gets to go along for the ride. The grandiloquent Dona Felipa Moniz de Perestrello seems much too refined a character to brave the briny deep with a boatload of testosterone-driven sailors. Yet this is the premise of DiPerna's first novel as narrator Felipa takes the reader on a genteel tour of 15th-century Portugal, an exotic Canary Island called Gomera (where she is greeted by a woman governor who is actually Christopher's secret paramour), and, much later, a weed-strewn expanse of ocean before the discovery of San Salvador in 1492 and an island full of naked and allegedly happy Indians. Along the way, we learn that Felipa was something of a closet feminist in the hillside convent above her native Lisbon where she was raised, learning how to read and write without much help from the nuns before ``The Admiral'' notices her during one of his visits to attend mass. The high-profile couple first sets up housekeeping on the little Portuguese island of Porto Santo, which Felipa's late father had discovered in 1418. We also learn that the Great Man- -whom Felipa calls ``my husband'' with annoying frequency--is an inadequate lover, not exactly a shocker. In addition to the stilted dialogue, there is some astonishingly insensitive ethnic language here related to the slave trade--and the writing's not good enough, the story not deep enough, to chalk this up to historical context. The actual sailing adventures gather steam late in the game when Felipa has a passionate affair with the captain of the Pinta, and even he sounds like a talking head. It's a good idea--the discovery of the New World seen from the point of view of a woman in the premodern 15th century--that deserves more sensitive exploration.