Groton - Really, the only common denominator was the song itself with its distinctive red, white and blue melody.

Thirteen varied and independent vocalists gathered Friday night in the Dealey Center at the Naval Submarine Base. Some were actual submariners; most were civilians. Some arrived in evening gowns or Sinatran finery. Others showed up in entertainer-casual as defined, perhaps, by "American Idol" chic - and a few even appeared to have bounded off the weekend couch, tournament brackets in hand, to race over for just this specific competition.

Indeed, this was the base's Second Annual Birthday Ball Sing-Off, and all these folks were there for one reason. The winner gets to sing "The Star-Spangled Banner" at the 113th Submarine Ball, taking place April 13 at Foxwoods Resort Casino.

In the end, a four-man panel of judges selected 18-year-old Laura McKee of New Fairfield as the winner, beating two other finalists, Stephanie Allyson Barry and Brittney Longyear.

Judges were Capt. Dave Roberts, commanding officer of the Naval Submarine School; master chief musician Gregory W. Dudzienski, assistant director of the Navy Band Northeast; Tom Russell, retired submarine veteran and chaplain of the SUBVETS Groton base; and Nashville-based country singer Sean Patrick McGraw, who has toured with Toby Keith and Trace Adkins and whose songs have been covered by such acts as Montgomery Gentry.

The format for the evening was that the 13 participants, selected from well over 100 applicants, would sing a song of their choice. The three finalists then returned separately to the stage to offer an a cappella rendition of "The Star Spangled Banner."

"To sing it at this birthday? Oh my gosh," said McKee, who heard about the contest from her longtime voice teacher. "All of these men and women are so passionate about what they do. It's an honor."

McKee's first song of the night, "Jimmy," the Act One closer from "Thoroughly Modern Millie," reflected her passion for Broadway and classical music. As the final singer in the opening round, her choice also represented yet another stylistic offering in an evening where competitors pinballed from archival gospel, Nashville country, modern R&B, American standards, and contemporary pop.

It was a diverse prelim, but the song on everyone's mind was, of course, the national anthem.

One of the elements in play, of course, was that, in terms of structure, it's not an easy song to sing. It requires power and dynamics and range - and the melody roller-coasters between peaks and valleys and back.

"It's very hard to sing," McKee said. "You've got to have a lot of control over your voice." Although she'd sung the anthem before a basketball game once, McKee said Friday was the first time she'd done it in a competition.

"It's completely different when you're not being judged," she said. "You're not so focused on being perfect. Tonight, though, I just let it go and it turned out for the best."

"Oh yeah, it's a real hard song to sing," said competitor Noelle Pollack, "and people mess it up all the time."

"You can either sing it or you can't. There's no getting around it," laughed competitor Rudy Taylor, a machinist's mate fireman assigned to the USS Toledo. "(It requires) a lot of range and a lot of passion and you have to put a lot of thought into singing it."

Regardless of whether the competitors ultimately made the final three, there seemed to be a pre-show attitude that supported a traditional approach to the song's interpretation. This bucked a trend, in recent years, where many entertainers use the "Banner" as a melodic trampoline from which to leap into self-aggrandizing vocal heroics.

McKee, as per her winning rendition, was resolved. "I believe you're supposed to sing it how it was written."

One of the competitors, Jackie Guerrera, said that just the act of rehearsing the song the week before made a big impression on how she wanted to come across.

She said, "You don't want to stray too much from the original melody of the song. It's not meant to show off your voice, it's meant to give the message of the song. ... You can add a few little vocal tricks - nothing Whitney Houston crazy - just enough to make sure people remember you."

One of the evening's judges, McGraw, has sung the anthem at numerous events, including before a Chicago White Sox game.

"I think most people oversing it," he said. "Personally, I try to sing it with some reverence or tradition. It's not about you, it's about the message and being an American."

"You want to do so well. You don't want to sound like every other person, so you try to personalize it," Taylor said. "But you have to be careful. It's the national anthem, it's not your own personal song. It can't be about you, it's about America."

Along with Taylor, other active duty submariners in the Sing-Off were Machinist's Mate Third Class Wesley Norton, assigned to the USS San Juan; Yeoman Second Class Alex Keun of the USS Virginia; and Lt. Commander Jeremiah Minner, an executive officer of the North Dakota (SS 784).

The other singers competing were Yvette Mitchell, Shauna-Beth Paradiso, Jamie Salvatore, Noelle Pollack, and Bonnie Suroweic.

r.koster@theday.com