I stumbled across something strange one night playing POTC. I was battling another ship that had special charms protecting it. I kept doing damage to the ship each turn I took, which in turn, gave me experience points.
However, since the ship had purchased so many charms or whatever it had protecting it, it would never completely sink. I would attack, take SOME damage and so would the other ship. So I would attack again.
Over and over I attacked and gained XP until my health would run out. Then I would simply pay the 1500 gold or whatever it cost to repair my ship and start all over again. It was like a bug in the game. I kept attacking and getting more XP but the ship just kinda stayed at the same damage level.
I ended up repairing myself from total damage probably 20 times before I finally ran out of gold. It was basically like I was just buying XP with gold. I have never been able to find that situation again.
So heads up, if any of you run across that situation. You might as well spend all the gold you can gaining XP. If possible, maybe you can write down the name of the ship and see if you can invite him to your crew. Then you can battle him at will.