Use chain-shot, aim for the hull

From Create Your Own Story

Midnight's cannonballs tear through the Portuguese galleon's hull with ease. One of them eventually hits the powder store, causing the entire ship to explode spectacularly. When the smoke clears, just a quick glance at the ship's charred remains tells you that it's no use to look for survivors... or salvageable cargo.

"Congratulations, captain," mutters Roderigo darkly.

Your men grumble between themselves, blaming you for this failure. YOU LOSE 1 AUTHORITY POINT.

Now it's no use to wait in ambush : the galleon's remains will make other ships wary of this place. No choice but to go back to the high seas and find something else to do.