Two winters ago, when the husband-and-wife duo of Alaina Moore and Patrick Riley began recording music under the name Tennis, they did so as a way to ease their sense of social alienation following a seven-month sailing trip along the Atlantic seaboard. At the time, the college sweethearts never suspected that their casual project would quickly become one of indiedom’s most buzzed-about new bands.

“We were having trouble readjusting to the fast, crazy pace of normal city life,” recalls Moore, speaking to the Straight on the line from her apartment in Denver, Colorado. “It was hard to explain that to our friends, and it made us feel kind of isolated. So we started to make music, because it seemed like a better way of describing something that’s ineffable and really personal.”

Unexpectedly, the band’s music found its way onto tastemaking web sites, and record labels soon came courting. “A few months later we were signed to Fat Possum,” remembers Moore, a trace of bewilderment in her voice. Tennis, by then performing as a trio with drummer James Barone, released its debut album, Cape Dory, in early 2011.

“We didn’t even think anyone would ever hear our songs,” admits Moore. “I also kept a sailing blog the whole time we were going, but basically no one read it. It was just for me and Patrick, and for our own memories. That was enough for us. We were really happy with that.”

It’s no wonder that the band’s music has earned far more attention than the singer-keyboardist’s blog ever did, as Cape Dory is packed with blissfully soaring melodies and Riley’s ’50s-tinged guitar riffs. The sock-hopping tunes act as a sunny accompaniment to lyrics that read like a travelogue of the couple’s time spent at sea; the organ-drenched fan favourite “Marathon” describes the perils of changing tides and weather forecasts, while the breezy opener “Take Me Somewhere” conjures up images of “crystalline water” and “manta ray shine”.

As a result of their nautical adventures, Moore and Riley’s romantic relationship became stronger than ever, and this comes across in Cape Dory’s heartfelt love songs. On the slow-burning standout “Pigeon”, Riley lays down sweetly chiming guitar licks while his wife vows, “I will be there, I promise to take care of you.”

Such sentiments make the album a beautifully evocative document of a once-in-a-lifetime trip. For the band’s next release, expect Tennis to turn its attention away from retro-pop-infused tales of love on the high seas. Entitled Young and Old, the forthcoming LP was recorded in Nashville, Tennessee.

“I listened to a lot of Todd Rundgren,” says Moore of her recent influences. Chuckling, she continues, “I don’t know how apparent that will be when you hear this record, but that was something that I was really looking to for inspiration.”

Audiences can get a taste of the band’s new sound in the form of the recently unveiled single “Origins”. With its tinkling piano chords, buzzing synth lines, and sun-flooded chorus, it boasts a far bolder and more diverse sound than the outfit’s past work. Moore explains that part of the credit for this lush new style belongs to producer Patrick Carney, who is best known to music fans as the drummer for the Black Keys.

“We wanted someone to challenge us to not settle into our comfort zones, which we had done on the first record,” she says of the decision to work with the esteemed alt-blues rocker. “No more surf beat. It was really fun to let ourselves go in that sense, because we like a whole wide range of music, not just ’50s girl groups or the Beach Boys.”

Given the romantic back story of Tennis’s founders, it’s only fitting that Young and Old will be released on Valentine’s Day. “We are either doomed or destined to be known as this very couple-y band,” the singer observes. “We didn’t even mean for it [the marriage] to be a big deal or a well-known fact when we first started to do interviews. We didn’t really even understand how press worked at the time, and that ended up being the fact that people were most interested in.”

The hint of frustration in the frontwoman’s voice indicates that she’s growing tired of her band’s origins overshadowing its music. “We had actually been talking about trying to distance ourselves from the married-couple aspect and be thought of more as a three-piece,” she reveals. “And then suddenly our album’s being released on Valentine’s Day and completely affirming the entire thing.”

Laughing off her annoyance, she finishes: “I’m okay with it. I’m just going to accept it.”

Before the album arrives, Tennis will be wrapping up its successful 2011 campaign with one final North American tour. The band’s busy live schedule poses a challenge for Moore, who admits that she has “stage fright beyond words”.

Luckily, her jitters have improved in recent months, partly thanks to lessons learned during those now-mythic months on the ocean.

“I feel like sailing prepared me a lot for that moment where you just say yes to the risk and commit to the decision,” she reflects. “When we decide to go to sea, we don’t know what the conditions will be like until we’re really there, and once you’re there it’s often impossible to turn back. You’re set adrift, you need to finish. It’s like that to really pursue music and perform.”

Tennis plays the Biltmore Cabaret on Tuesday (December 13).