No one can teach you how to swim with watermelons, it's something you have to learn for yourself. These words are oddly prophetic when it comes to Swimming With Watermelons, the new show at the Vineyard Theatre. Similarly, can one be taught how to write an effective musical? Perhaps, but Diane Paulus and Randy Weiner are still learning.

The two conceived and directed this show, based upon the real experiences of Paulus's mother. A Japanese woman who fell in love with an American serviceman during the occupation of Japan following World War II, she moved to the United States and didn't see her family, which refused to accept the marriage, for decades.

The relationship of George (Rachel Benbow Murdy) and Tomoko (Emily Hellstrom) is not an easy one: The two spend most of the play working at breaking down external and internal barriers that keep them from getting together. There are two other major romantic subplots, but they're played mostly for comedy, with traditional ideas, traditional problems, and traditional resolutions.

Far greater creativity comes from the production. The cast's four women (also including Anna Wilson and Jordin Ruderman) play all seven major roles in the show, crossing gender and ethnicity lines with wanton, reckless abandon, all mostly convincingly. That the actresses frequently dip into caricature or overly-broad portrayals is perhaps to be expected, since Swimming With Watermelons was conceived as a show being put on by its characters. Yes, there are two characters named George and Ira, but there are far more clever elements. Myung Hee Cho's sets and Ilona Somogyi's costumes add plenty of flavor, and the staging uses costumes, sets, and props in many inventive ways, such as flashlights and wiper blades simulating an army jeep, or a Japanese lantern on a pole creating the perfect atmosphere outside.

The musical elements of the show are unfortunately less effective. Swimming With Watermelons is, for want of a better term, a karaoke musical. Whenever the characters' emotions burst into song, they are sung above recordings of famous songs from the period. "Night and Day," "Temptation," "Stormy Weather," and so on.

This device is novel at first, but grows wearying quickly. Too often, the songs feel shoehorned into the plot - the play itself, without the songs, is entertaining enough, but the dramatic machinations worked here are frequently unfortunate. Was Yvonne, the woman of German descent with whom the Jewish Ira falls in love, really made a librarian for any reason other than to find a reason to use "I Could Write a Book" in this show?

It's hard to tell. Swimming With Watermelons has such a tenuous grasp on reality as it is, that adding musical moments that don't really musicalize the characters (extraordinarily difficult, since the songs weren't written for the characters) severs the already fragile threads keeping the show afloat. The show doesn't really need the songs, and none of its best moments utilize them at all. This isn't a show where you dread the songs, but you certainly don't look forward to them.

Swimming With Watermelons, then, may be a bad musical, but it's far from a bad show. It's nice to see a show brimming with energy, creativity, and heart, elements that can all too easily be lacking. Sadly, they aren't enough. Swimming With Watermelons is a good play with good songs, but even some of the greatest pop tunes America knew in the 20th century don't necessarily work in a musical.

Swimming With Watermelons
Vineyard Theatre, 108 East 15th Street
Schedule and Tickets: (212) 353-0303
Running Time: Approximately 90 minutes with no intermission