DAMES AT SEA IS A PASTICHE of all the 1930s musicals you've never seen but know all about anyway, the sort of show in which the heroine introduces herself as Ruby, "just a simple girl from Centerville, U.S.A." who's come East with "nothing but a pair of tapshoss and a prayer in my heart."

"Mr. Henneney is right," she announces halfway through the first act. "Broadway is a jungle. I'm going back to Centerville where people are nice." Surprisingly enough, she never does, though, and at the end of her first performance -- on board ship, since the WPA is bulldozing her theater to turn it into a roller risk--her boyfriend Dick assures her that "All Broadway is at your feet" where, as Groucho Marz once remarked, there's always plenty of room. There has to be, because the whole cast spends most of its time tapdancing over the whole goddamned stage, as Holden Caulfield or somebody eloquently put it.

It's the sort of show, in fact, that sets out to be native so determinedly and so good-humoredly that almost everyone likes it. If it weren't so confident that determined naivete and good humored stupidity are the height of sophistication and intelligence, this show would be a classic.

THE CURRENT PRODUCTION is pretty close to perfect. Rita Hargrave successfully accomplishes the remarkable feat of directing and choreographing a show about a chorus girl without a chorus. One particularly effective moment occurs about halfway through Ruby's third or fourth misunderstanding with Dick. In this case she has caught him kissing Ellen Martin, the established star--the one who gets sick later so Ruby can take her place--who's been ravenously pursuing him. When Ruby breaks into a mournful little number called "Raining in My Heart," the rest of the cast comes out to dance around her in plastic raincoats and transparent umbrellas. The music, ably conducted by Paul Schommer from the piano, has quite enough life to get through the show, though probably not enough to survive it.

All the actors are funny, although Martin, Greenberg, Paul Jackel as Dick and William Nabel as Captain Courageous are the best. They all play with the right amount of archness, overacting just enough to remind us that we are, after all, superior to this sort of thing nowadays. It's a little bit like taking candy from a baby, but it makes for a pleasant enough evening at the theater.