Elizabeth (and the Medallion) taken aboard the Black Pearl
The first climax is 41 minutes in after Elizabeth requests ‘parlay’ and agrees to be taken to the Black Pearl. Her surrender and transfer of the medallion effectively ends the attack on Port Royal, but her imprisonment by Captain Barbossa raises the two questions: What will happen to her, and why is the medallion so important? Her capture escalates the stakes for the other characters, and the plot moves from Port Royal to the seas.
Jack and Elizabeth marooned, Will captured
The second act responds quickly, sending Will and Jack after her in the ‘commandeered’ Interceptor, along with a newly-recruited team of pirates and a bit of backstory. This is followed by a long sequence where Barbossa monologues to Elizabeth and reveals the undead nature of his crew. After a brief climax at Isla de Muerta where Will rescues Elizaebth but abandons Jack, the reshuffled crews convene at a battle at sea. The end of this battle comes at 1:35 when Barbossa defeats the crew of the Interceptor, taking Will and the medallion and abandoning Jack and Elizabeth. The next question posed is: how will Elizabeth and Jack escape? Will they be able to stop Barbossa from killing Will and ending the curse?
Barbossa's death and his crew's defeat mark the end of the third act
The climax of the third act answers: yes, yes and no. After joining with the lawful forces of Norrington, Jack and Elizabeth successfully engineer an encounter that saves Will’s life and corners Barbossa’s crew in a battle that proves unwinnable after the lifted curse reverts them to their mortal states. This victory comes at 2:03, but after the 2-hour mark Pirates indulges in a short epilogue that does not fit with the rest of the three act structure. While the main threat has been defeated at the end of the third act, Will and Elizabeth's relationship and Jack’s fate are not resolved until approximately ten minutes later. After two acts at sea, the characters return to Port Royal, where Jack's criminal statues as a pirate is resolved in an escape with help from Will and Elizabeth.
Post-third act, the characters finally receive closure
First Act: approx. 41 minutes long, 0:00 - 0:41
Second Act: approx. 54 minutes long, 0:41 – 1:35
Third Act: approx. 28 minutes long, 1:35 – 2:03
Plus 10 minute long ending segment, 2:03 – 2:13 Images from ScreenMusings.org