Harbor cruise mixes a crazy cocktail

For the 300 or so revelers aboard the 95-foot Rock On! concert cruise ship, civilization (and, thus, responsibility and real life) is fast receding in a boisterously happy haze of music, cocktails, and camaraderie (either friendship-fueled, alcohol-enabled, or both). For roughly three hours - between departing Rowes Wharf at 8 p.m., looping around the mouth of the harbor, and docking back into reality at 11 - all is right with the world, or at least our little water-buoyed corner of it.

“People go a level of crazy on a boat that you don’t see in other places,’’ Dan Millen, president of Rock On!, jovially informs me beforehand. His company hosts about 25 concert cruises a year, and he rarely misses a chance to get out on the sea himself. Besides watching the logistics of ensuring that everything runs smoothly, Millen says he delights in introducing the bands and getting the party started. And then making sure it keeps going.

Back on the cruise, by 10 p.m. the crowd is singing along with the band and dancing stem-to-stern. Eventually, inhibitions are thrown overboard. Emboldened young women engage in a daring bit of pole dancing (albeit fully dressed). Young men do chin-ups on the ship’s pipes - to impress the pole dancers perhaps? One thing’s certain: Millen’s claim that the crowd is having a good time is a little like saying Bono sings with a rock ’n’ roll band.

In fact, to the baseball cap-clad dude standing beside the makeshift stage, who, eight songs into the Joshua Tree’s first of two sets, never stops playing air guitar, Joshua Tree singer Mike Golarz might as well be Bono.

The air guitarist is Joe Hurley, 45, of Needham. “Oh, yeah, I go on ‘booze cruises’ a lot,’’ says Hurley, taking a breather but not sounding or looking the least bit winded from his workout. Another thing he’s done a lot is see U2 in concert (about eight times by his count) and he proudly announces that he’s already got tickets to one of the band’s September dates at Gillette Stadium.

Golarz, a rangy guy with a tenor voice to match, doesn’t much look like his world-famous counterpart. But his singing, especially set against the backdrop of Ivo Matos’s Edge-like electric guitar chime on numbers such as “Bullet the Blue Sky,’’ bears an eerie resemblance to Bono’s clarion-call vocal approach.

“This is like a big party,’’ says Golarz, whose band is in its third year of performing on the cruises. “It’s like going to someone’s backyard party.’’

The Joshua Tree has been together about seven years and plays somewhere almost every night of the week. “You can’t go wrong’’ playing U2 music in Boston, Golarz says with a smile, “especially around St. Patrick’s Day.’’

There’s a special feeling you get on a boat out on the water. It’s the strangely simultaneous sense of escape and connectedness - to the elements, to the fantasy that you could just keep going and head for the horizon. Jackie Lowe, 30, says she couldn’t wait for the adventure to begin.

“It was 2 o’clock and I was e-mailing my boss,’’ says Lowe, a money manager who’s now two-fisting it, a beer in each hand. “I’m like, ‘Three hours and I’m outta here and on the booze cruise!’ ’’

Perhaps wanting to be spared further hourly updates, her boss let Lowe out of work at 4:30 p.m. She’s here for a 30th birthday bash for her friend, Christine Wilkinson, with whom she grew up in Marshfield. Meanwhile, Christine’s mother, who has carved out a sliver of space on the deck, scowls at the volume with which the Joshua Tree is playing “Beautiful Day.’’

“I wouldn’t be here if it wasn’t for [Christine]. I don’t know U2, I’m too old,’’ says her mom, who’s revealing neither her name nor her age. “I prefer [entertainer] Jimmy Plunkett.’’

Really? Over Bono? Is that even allowed in this town?

She looks puzzled. “Who’s he?’’