MIAMI — Cayamo concerts are different in several ways. They start on time. They last only an hour. And the speakers hanging from the ceiling tend to sway.
Sometimes the musicians do, too.
"Usually I go where I want on stage," John Prine said. "But here I go where the ship takes me."
Cayamo is an annual music festival at sea featuring performers of Mr. Prine's ilk - singer-songwriters with acoustic guitars and devoted fans. There are bands, too, and amplifiers, and all of the attractions that go with any other Caribbean trip. That means sunshine, shore excursions, a laid-back vibe and too much food.
Mostly the 2,000 passengers come for music. That was the case when my wife and I took our first cruise in February to enjoy Cayamo aboard the Norwegian Pearl.
It was a seven-day excursion - six days of concerts and one day listening to musicians tune. Or so it seemed.
Not to quibble: The music was great. Main attractions included Mr. Prine, Brandi Carlile, the Indigo Girls, Steve Earle, Patty Griffin, Richard Thompson, Loudon Wainwright III and Buddy Miller. But one of the delights was discovering lesser-known acts such as Scott Miller, Chuck Cannon, and Roddie Romero and the Hub City All-Stars.
A partial lineup for February 2012 includes Mr. Prine, Mr. Thompson, Mr. Wainwright, Lyle Lovett, John Hiatt and Keb' Mo'. For now, all cabins for the trip are booked, but Cayamo anticipates some cancellations and will keep a waiting list.
Acts perform in half a dozen cozy venues, the largest seating about 800 people. On our trip, shows began in the afternoon, and music continued into the wee hours each night. One jam session in the atrium lasted until 2 a.m. and involved more than a dozen musicians from five bands.
For the many music geeks on board, it was like being a spectator at a golf or tennis tournament. You'd study the schedule at the beginning of the day and plan where you wanted to be when, who you were willing to miss and who you absolutely had to see.
Shows went off like clockwork. The first full day at sea, options included Mr. Wainwright at 4 p.m., Mr. Earle at 6 and Mr. Prine at 8 - a singer-songwriter power trio.
There was music everywhere, even in the chapel, where equipment being stored included drumsticks on the altar. Lots of passengers brought along a guitar or fiddle for amateur jam sessions.
This was the fourth year for Cayamo, and about 175 passengers had made every trip.
"How's the recession going for you?" Mr. Wainwright asked his audience. "I'd say you're doing pretty well, because I know this cruise costs a load of money."
Prices for the February cruise start at $1,235 per person for double occupancy interior cabins, so Jazz Fest or Bonnaroo would indeed be cheaper. But Cayamo has comfy chairs and no Port-O-Lets, and you're always within walking distance of the swimming pool, a dining room and your bed.
"It's an experience that can't be replicated on land," said Carolyn Spencer Brown, editor of CruiseCritic.com.
Theme cruises are common - they're available for fans of history, dancing, wine, nature or knitting, Ms. Spencer Brown said. But she ranked music No. 1 in variety and popularity, with the cruise industry using it to attract first-time customers.
"Anything that encourages people who haven't cruised before to get on a ship is a good thing," Ms. Spencer Brown said.
Music on cruises is nothing new; the Titanic had it. There was a time when the main attraction might be Wayne Newton's cousin or the former drummer for Three Dog Night, but options are hipper now.
Genre cruises showcase jam bands, goth, R&B, country, gospel and jazz. Sixthman, the Atlanta-based company behind Cayamo, also offers cruises for fans of alternative rock, Southern rock and even Kid Rock.
With record sales in decline, performing at sea becomes an even more appealing option for musicians, Sixthman founder and CEO Andy Levine said.
"Artists are seeing their chance to be superstars diminish, so they're trying to build a healthy fan base and take care of them," Mr. Levine said. "The thing we hear the most from artists is that they feel a huge lift from the cruise because they get exposed to potential new fans."
Mr. Levine became intrigued by the concept of music at sea a decade ago, when he managed the band Sister Hazel and scheduled it for a four-day cruise.
"We had a great four days," he said. "We were able to share space without it being awkward for the band or the fans. I've always liked that it's just us, and everyone is there for the same reason. There's a certain power in that."
On my Cayamo trip, the performers seemed to have as much fun as their audience, even if the occasionally bumpy ride made standing at the microphone a challenge.
"If I had told my teachers about this, they would have thrown me out of school: 'I want to sail around the Caribbean singing my songs,' " Mr. Prine said with a chuckle. "Not a bad gig."
Many of the musicians were Cayamo repeaters, among them Mr. Earle, accompanied by his wife, singer Allison Moorer, and their young son.
"Welcome to my vacation," Mr. Earle said after performing his first song.
The division between artist and audience tended to dissolve, because many musicians hung out in the same bars, shops and dining rooms as the other passengers. We sat next to Mr. Earle at a safety briefing, crossed paths with him at lunch and saw him on the jogging track, although he wasn't jogging.
Performers sat in on each others' sets. There were only a few nautical tunes, and thankfully no "My Heart Will Go On" or "The Morning After." Mr. Wainwright did joke he had seen Ernest Borgnine and Shelley Winters on board.
The setting made for unique moments. The Canadian band Enter The Haggis performed one afternoon outdoors. Midway through a song, their lead guitarist set down his instrument and took a running leap into the swimming pool. He then climbed back onto the stage and resumed playing as another band member toweled him off.
During an inspired bluegrass rendition of "Orange Blossom Special," Steep Canyon Rangers fiddler Nicky Sanders added bits of "Norwegian Wood," "Sabre Dance" and the Simpsons' theme.
"I love playing train songs on a boat," he said.
There were three shore stops, but my wife and I never left the ship. Instead we rested up for the next show.
One evening, as the Pearl pulled back out to sea, there was a big clank just before Mr. Prine's concert began.
"That," he said, "is the first time we ever had an anchor open for us."
CAYAMO CRUISE: http://www.cayamo.com/. Seven-day cruise from Miami on the Norwegian Pearl to the Caribbean, Feb. 5-12. All cabins have been booked, but a waiting list is available for rooms that open up due to cancellations. Other niche and genre music cruises listed under "Events" at http://www.sixthman.net/.