raywest

Question: Why did Will specifically need the Black Pearl to free his father? The only thing the Pearl had going for it was the speed. Wouldn't a ship fitted with more firepower be better suited for taking down the Dutchman?

Answer: The Black Pearl is the only ship that can catch up to the Flying Dutchman.

lionhead

Answer: As you mentioned it is the fastest ship. Other reasons, it's a ship Will knows it is one that he has an opportunity to bargain for by betraying Jack Sparrow to his enemies.

raywest

Also, Will would have very little opportunity or the means to acquire another ship.

raywest