Breathing the same giddy air of early rock that fueled Ang Lee’s “Taking Woodstock,” Richard Curtis’ “Pirate Radio”—previously known as “The Boat That Rocked”—deals with a somewhat earlier episode, the constant broadcast of pop music into England from offshore ships when the BBC largely excluded it from the airwaves.

The boat Curtis portrays, in 1966, houses a floating collection of eccentric DJs overseen by an equally oddball owner named Quentin (Bill Nighy). Among them are Dave (Nick Frost), a chubby lothario; Thick Kevin (Tom Brooke), whose nickname says it all; rebel-hunk Mark (Tom Wisdom); morose Simon (Chris O’Dowd); scruffy recluse Angus (Rhys Darby); and the sole female, Felicity (Katherine Parkinson), a lesbian jill-of-all-trades. The sparkplug, however, is an expatriate American, The Count (Philip Seymour Hoffman), who’s clearly the station star. That position is threatened, though, when histrionic bad-boy Gavin (Rhys Ifans) returns from a stint in the U.S. to resume his old role in the UK.

As the plot begins, there’s another arrival, Quentin’s callow young nephew Carl (Tom Sturridge), just kicked out of school who’s sent by his mother, a haughty sort who later makes an appearance herself. Like the character played by Demetri Martin in “Woodstock,” Carl becomes the innocent abroad, the young man gradually sucked into a new and vibrant, if very strange, environment, which includes Dave taking it upon him to see to it that Carl loses his virginity during his stay, either with one of the women occasionally brought on board from the mainland or with Quentin’s visiting daughter Marianne (Talulah Riley), with whom the young man is quickly smitten. Yet another thread is added to Carl’s story when he comes to suspect that one of the DJs is his long-absent father, whom his mother has sent him to meet.

In addition to the rivalry between The Count and Gavin, which becomes a major element of the plot, Curtis frequently switches back to England, not only to show listeners reacting to the broadcasts but to lampoon government minister Dormandy’s effort to find a way to shut the station down. Dormandy is played straight out of the insufferable martinet’s handbook by Kenneth Branagh, who’s obviously enjoying the chance to go cad, and he has a good partner in Jack Davenport as Twatt, Dormandy’s assistant, who’s given the task of coming up with the means to do so.

The large ensemble cast on the boat does mostly engaging work under Curtis’ permissive direction, with Hoffman, Ifans and Frost predictably standing out among the DJs and Nighy pulling off yet another marvelous portrait of British upper-class goofiness. And the film would probably sink were it not for the fact that Sturridge holds his own against them and the others as the young man who grows to love the eccentricity around him.

The boat does, of course, ultimately close down shop in an extravagant finale designed to show that rock will live forever. The sequence is pulled off well by the production crew, whose work in it cap off solid contributions throughout, and Danny Cohen’s widescreen photography is excellent throughout, even using the close quarters of the ship cabins nicely in the more intimate scenes. And, of course, the picture employs a raft of pop tunes from the period for atmosphere.

There’s one thing lacking in “Pirate Radio”—the comeuppance scene for Dormandy and Twatt that one eagerly expects. But though Curtis’ movie lacks the edge it might have had, as a genial, old-fashioned comedy about the spirit of the sixties, it’s enjoyable enough. And it would be a fine complement to “Taking Woodstock.”