Talk to a store owner about business and he will tell you that a nasty pirate and his very fast ship, the Blue bird, are plundering merchants. They offer you 50000 for sinking that ship.
Go to Bermuda and talk to the store owner about the blue Bird.
Go to the tavern owner and ask him about what he knows. He will direct you to the store owner on Puerto Principe. Go there.
Talk with the merchant on Puerto Principe to learn that Pascal is an evil person with a nice mask.
Go to Bermuda and talk to the Shipyard owner about his dungeon (Don't pay the 20000). Go to the Ruin Shore and enter the cave in the jungle. Go to the dead end behind the white ball. Don't touch it or you will get foul-smelling "company".
The character hears something and waits. You see the crew of the Blue Bird. Leave the cave and go to your ship.
Fight the Blue bird with chain balls to negate its speed bonus and sink or board it.
If you sink the ship, you can collect the money from the store owner that asked you for help. If you keep the ship, it will be considered a violation of the treaty and you receive nothing. Well, you do have a fast xebec. Ask for rumours and you learn that a trader is shipping some wares. You can plunder that ship to gain a big reward.