Pirates present so many good metaphors for a critic it is hard to choose between them, so I don’t think I’ll bother. To say this film walks the plank and then jumps the shark may seem incoherent, but I see no reason why this review should contain any more coherence than the filmmakers saw fit to put into this flapping redundant appendage of a movie. I have seen all four POTC movies in the cinema, which means I have had 143 minutes of decent swashbuckling fun and a geological 457 minutes of moaning pitifully under my breath. This ratio is more than enough to kill any goodwill I had for the first instalment stone dead.

It turns out that we’ve been tricked. I’m beginning to think that Johnny Depp’s original drunken sailor act was never funny to begin with, and we all underwent some kind of mass hypnosis. In this instalment, Depp may as well be the actor impersonating Jack Sparrow outside the ride in Disneyland for all the freshness and charm he manages to dredge up from our memories of first time around. It’s probably not the actor’s fault, since the filmmakers have contrived to give him some extraordinarily dull material to work with. The plot involves yet another Macguffin, this time a Fountain of Youth which the Spanish, the British, and evil pirate Blackbeard (Ian MacShane) are all racing for. I say “racing”, though in the time it takes to actually get there it feels like continental drift should have misplaced the fountain’s location. I found myself wanting to stand up and yell at the screen "They're PIRATES! They're meant to be FUN! How the hell could you create something so eyeball-meltingly boring out of something so inherently exciting?” There is a massive section in the middle in which, during a transatlantic voyage (and if director Rob Marshall’s real intention was to accurately recreate the experience of travel in the days before one-day flights, oh boy did he succeed) characters do nothing but walk around each other explaining the plot.

I am loath to steal another critic’s lines, but Mark Kermode’s description of POTC: Dead Man’s Chest as a film in which a bunch of stuff happened, but nothing actually happened is all I can say about this one too. Without any kind of wit in the script or reason to care about any of the characters, everything that happens in the film is just a series of events, signifying nothing. It says a lot that the only two laughs I gave throughout involved people dying brutally and unexpectedly. One of these is boldly holding a Union Jack as he dies; while it was nice to get an antidote to the recent pageantry of the royal wedding, I still felt a little patriotically irritated the British armed forces were portrayed as having the competence of Dad’s Army with nicer uniforms.

The actors are not having nearly as much fun as they should – MacShane disappointingly underplays the role of pantomime villain, Penelope Cruz is meant to be that producer’s favourite buzzword, “feisty love interest”, but seems to be concentrating hard enough just getting English sentences out, and only Geoffrey Rush gets any good piratey mileage as Captain Barbossa, a figure by now far more fun than Jack Sparrow. Tacked on to all this, presumably because the producers felt that audiences would miss the furniture-worthy woodenness of Keira Knightley and Orloondo Bland, sorry Orlando Bloom, is a vacuous love story between a mermaid and a priest so wet he makes Bloom look like Humphrey Bogart. Speaking of mermaids, though they are the best thing in the film (for a male audience at least), I have a serious moral problem with any film that can feature an action sequence in which heroes stab and kick in the heads of attractive naked women. I know Disney isn’t famed for its enlightened attitude to female emancipation, but still.

The action sequences are my biggest problem with the whole thing, for a personal reason – I love swashbucklers. I still consider The Princess Bride one of the all time great movies. You know what was good about the sword fights in that? The camera didn’t cut or leap about, but just watches two fencing masters go at each other for two minutes, exchanging witty repartee the whole way. In this film, the fights involve cuts so fast you have no idea whose sword is where, who is in danger, who has the upper hand, and most criminally, they are never combined with that fantastic theme tune to create an actually enjoyable, climactic sword fight. What we left with has all the excitement and internal logic of a semi-paralytic drunken brawl outside Cindies.

It could just be that all this boredom is designed to get us sympathetic with a bunch of characters looking for a fountain of youth. Certainly upon leaving the cinema I had to check a mirror to make sure my hair hadn’t silvered. This is one of the most cynically, ineptly and pointlessly put-together films I have ever seen. By now the only relationship the franchise has with a rollercoaster is that you will be waiting for a long time and end up wanting to be sick.