British helmer Richard Curtis directs a cast of his countrymen in this comedy set in Britain in 1966. While the BBC would allow only two hours of rock and roll to be played on its airwaves a week, pirate stations broadcast music to the pop-starved masses.

Comedy flounders in a sea of mediocrity.

This Britcom boasts a stellar ensemble cast, a commercially savvy writer-director in Richard Curtis, and a promising set-up: the motley crew aboard a pirate radio ship in the North Sea in the mid-1960s, and the British government’s bumbling efforts to shut down the service.

So why was I frequently wishing the boat would capsize, with no loss of life, given the precious cargo? Partly it’s the interminable 134-minutes running time, which stretches the yarn beyond breaking point and results in too many flat spots when the gags dry up and interest flags.

But The Boat That Rocked fails to maintain buoyancy mostly due to Curtis’ inability to invest the film with his customary sharp wit and snappy dialogue, coupled with an unusually mean-spirited tone and questionable casting. It’s a rare misstep from the writer of Four Weddings and a Funeral, Notting Hill and Mr Bean.

On board Radio Rock, upper-class fop Quentin (Bill Nighy) presides over a ragged bunch of dope-smoking, sex-starved DJs including grizzled Yank The Count (Philip Seymour Hoffman), who jostles for top jock status with the egomaniacal Gavin (Rhys Ifans), chubby, unlikely ladies’ man Dave (Nick Frost), Thick Kevin (Tom Brooke), sad-sack Irishman Simon (Chris O’Dowd) and unloved Kiwi Angus (Rhys Darby). The boat’s sole female is Felicity (Katherine Parkinson), meanly described as a 'lesbian who cooks."

Quentin’s teenage godson, Carl (Tom Sturridge) is the new arrival, supposedly sent there as punishment by his lush of a mother (an all-too-brief turn by Emma Thompson) after being expelled from public school for smoking: pot and ciggies.

Meanwhile, stiff-upper-lip Cabinet Minister Dormandy (Kenneth Branagh), who regards pop music as evil, conspires with his hapless sidekick Twatt (Jack Davenport) to try to silence the station by fair means or foul"¦ conveniently ignoring the fact the station isn’t breaking any laws.

One subplot follows the crew’s efforts to help Carl lose his virginity and his quest to find his long-lost father, while another involves a short-lived marriage which is both unfunny and cruel.

The acting is mostly impeccable, particularly from the sardonic Nighy, a boisterous Philip Seymour Hoffman, and Ifans, while Sturridge is sweet and endearing as the naïve Carl.

But Branagh labours with the thankless task of playing a pompous ass who makes the antics of Yes, Minister look wonderfully subtle, and uttering leaden dialogue such as 'We have their testicles in our hands and it feels good."

Who’s to blame: Curtis the writer or Curtis the director? Both. In his second directing effort after Love, Actually, Curtis’ script inspired by the true story of Radio Caroline is flabbier than Dave’s paunch, relying on tricks like bad puns on the word 'knob,’ dopey lines like 'pull the pin on the love grenade," a cringe-worthy interlude in a bathroom, and an execrable joke about a thankfully rare bedroom mishap. Unlike the typical Curtis rom-com, there is precious little romance here, and most of the women are eye candy.

This is a lazy assemblage of sex, drugs and rock ’n’ roll clichés—and any comedy which features a character named Twatt isn’t trying hard enough. The soundtrack is a treat for 60s music buffs, peppered with hits from The Rolling Stones, The Yardbirds, Cream, The Who, Hendrix, The Kinks, Procol Harum, Australia’s Easybeats and many more.