It sounds like you've got an almost perfect setup here with the whole "Pirate" thing. Since I've been playing the Sid Meier's Pirates! computer game, I've got several ideas you can steal from that:
Have the PC be a young prince of an island nation. His father dies (or is assassinated) and an evil advisor plots to have the rest of the family, including the PC, his sisters, mother and maybe an aunt and uncle thrown into the dungeons so that he might take over the throne. The PC manages to escape and flees to the docks where he stows away on a ship leaving port.
He is discovered shortly thereafter and spends the next several years growing into manhood while being forcibly made to serve aboard ship as payment for his "passage". He learns to be tough, learns to sail, learns to fight. He is even growing rather content with his life at sea when one day a friendly but sad looking older man books passage on the ship.
It turns out that this fellow was once an entertainer loyal to the PC's father. He tried to fight against the usurper but failed and had to flee the island nation as well. He has spent the last several years moving from one port to another, always leaving before any of the new king's agents can catch up with him. But he recognizes the man who he knew to be the prince and sees an opportunity to stop running.
He reveals his identity to the prince and uses his charm to win over the majority of the crew. The PC is presented with an opportunity to lead the crew in a mutiny whereupon he takes over control of the ship. And now he and the bard are on a mission to discover the location of his surviving family and topple the current king so that he might retake his father's throne.
For adventure ideas you can have this character chasing all over the ocean looking for his family, sinking the ships of the False King, fighting other pirates, finding treasure to finance his revolt against the usurper and so forth. Watch some Pirates of the Carribean and Count of Monte Cristo and the stories almost write themselves!
You'll want a good set of ship to ship combat rules that suit the player's style (does he prefer to use his sailing skills to attack the enemy at range or ram and board?) and decide if you want to have gunpowder or something similar (magical cannons?). It'll be a swashbuckler's dream!