Films about boats tend not to end well, either in the film or for the audience watching it. Or in the case of Titanic, both. But this one from Richard Curtis – whose official title is probably king of the English rom-com – is slightly different, concentrating as it does on fun-lovin’, boat-dwellers.

Although it’s the swinging sixties, you can’t just turn on the radio and listen to the latest popular tunes of the day on BBC radio, because the beeb aren’t playing them. And retuning your wireless to find an independent radio station is harder work than it sounds, due to the fact the first one (London’s LBC, if you must know) didn’t started broadcasting until 1973. So how did the kids listen to the likes of The Who, Stones, The Kinks etc?

Broadcasting from a safe distance from UK mainland were the pirate radio stations. This groovy bunch of DJs gave the youth what they wanted – pop on their radio. The fictional vessel Radio Rock is home to a merry band of DJs, including ‘Simple’ Simon (Chris O’Dowd), ‘Doctor’ Dave (Nick Frost) and The Count (Philip Seymour Hoffman). Captain of this musical ship is Quentin (Bill Nighy), who welcomes his godson Carl (Tom Sturridge) on board, in a woolly attempt to improve his behaviour.

Let's do the time warp again...

It’s not all frothy fun and frolics on deck however, as Minister Sir Alistair Dormandy (Kenneth Branagh) attempts everything in his power to pull the plug on these musical pirates.

So, from the sounds of it, The Boat That Rocked has pretty much all it needs to make it enjoyable to watch: it has a bunch of top class comedians on board; is based during an interesting period of popular culture; as well as having the obligatory toe-tapping soundtrack. So how come it’s difficult not to feel a tad disappointed by it then?

Despite much of the comic talent literally on board, it’s nowhere near as funny as it thinks it is. Perhaps Curtis was too overwhelmed with directorial duties, and let the script float off into the distance. Or maybe it was a case of too many comic DJs, spoiling the boat? Either way, it was all far too middle of the road/ocean for its own good.

Curtis also struggles with the story in general. We’re introduced to all the characters on board, through the eyes of the naive Carl. And although that works well, at no point in the film does Carl actually have a position to fill on the boat, which kind of begs the question – what the hell is he doing on it then? As a device to forward the story, he was certainly a weak one.

And although the story probably needed the outside threat given by Branagh’s character, too much time is wasted on his domestic life at home. Let’s face it, you have a bunch of comedians on a boat, surely it would be a better idea to focus on them?

And even the arrival of the coolest dj on the planet Gavin Cavanagh (Rhys Ifans), which is supposed to stir up a right hornet’s nest of contempt and rivalry, soon dissipates into a chummy malaise.

None of this stops it from being a fun film. It’s just that it’s not a really, really funny film, which is kind of what you hope for with a cast like this. All you’re left with is, well, a somewhat sinking feeling.