Imagine an upper class English girl kidnapped by pirates when she was eleven, and eventually returned to her family. If this sounds familiar, you've probably either read the classic book A High Wind in Jamaica by Richard Hughes, or seen the movie. Whatever you may imagine,Jean Roberta has taken the grown-up Emily far beyond your--or the younger Emily's--wildest speculations. This is, indeed, a ''Bawdy Novella,'' but there is more to it than that. Emily is a smart, spirited heroine, adventurous enough to see the bright side of the unspoken (and unfounded) assumption that she must be ''damaged goods.'' When her romantic affair at a girls' school is abruptly ended because of her lover's cowardice, Emily tosses off the constraints of 19th century English society and returns to the sea on a more-or-less pirate ship, the Black Swan, manned by gay fugitives from the British Navy.