What, I wonder, possesses people to meddle with a winning formula?

Why replace your star forward with a less experienced striker? Why update the taste of the world’s favorite soft drink? More to the point, why saddle Indiana Jones with an obnoxious sidekick, a whiny love interest (played by non-actor Kate Capshaw), and a xenophobic diet of monkey brains for his second go-round?

The tragic fall from Raiders of the Lost Ark to its debilitating sequel should have been a lesson to the producers of Pirates of the Caribbean: Dead Man’s Chest, the sequel to 2003’s surprise hit Pirates of the Caribbean: The Curse of the Black Pearl, but they apparently weren’t paying attention in class. Let’s be honest: we all feared it but secretly hoped that director Gore Verbinski and his talented cast and crew might surpass our expectations and give us a follow-up worthy of the original. No such luck.

Pirates 2 doesn’t plumb the same kind of idiotic, gross-out depths as ’Temple of Doom (although that’s not to say it isn’t both idiotic and gross at times). No, its failings tend to be more a lack of imagination and a sad dearth of the winning humor so prevalent in the original. Most of the film flickers by in long boring stretches that play like cutting room floor footage from ’the Black Pearl (at 150 minutes the new film is endless). And Johnny Depp’s character, Captain Jack Sparrow, appears more a buffoon than a lovable rogue now, slapped all too often into slapstick situations (such as being trussed up on a spit as a cannibal entrée, for example).

So dulled by the film’s lack of invention is Depp that at times he actually slips out of character, forgetting to slur his words or add a qualifying “mate,” “love," or "savvy?” That’s probably a result of shooting not one but two Pirates’ sequels back to back: the man looks bushed!

As expected, ’Dead Man’s Chest relies more heavily on special effects than its predecessor, with Barbossa’s crew of crumbling, undead pirates replaced by Davy Jones (not the singer from The Monkees) and his crew of mutated marine life. The crew of the Flying Dutchman are a barnacled bunch indeed, but look decidedly less threatening when running through the island undergrowth after our hapless heroes (Captain Jack, it turns out, owes a debt to old tentacle-face, one he can only repay by finding the key that unlocks the fabled dead man’s chest). There’s also an unconvincing Kraken, which wakes.

Will Turner (Orlando Bloom) and Elizabeth Swann (Keira Knightley) return, of course, as do many of the original characters, but if anything they take a step backwards in terms of their development. Will seems insecure and less dashing than before and Elizabeth seems equally unsure of herself: in one scene she’s shown battling phantom menaces with swords drawn and in the next she’s swooning about on the sands pretending to expire from the heat. And her romantic interest in Jack is played too coyly for comfort.