Trading. Shipping cargo between isles of archipelago for money (if you watch the difference/trends in prices for different goods).Becoming a privateer. Capturing ships. Making a small fleet. Participating in naval battles.
Ability to improve your ship: durability, speed, maneuverability, cannons and crew count.
Becoming an admiral. Build a port or fort. Improve it.
And the list goes on.. but it looks like I answered a different question: "Crazy ideas you like to have (but most likely not won't get)"
Love this idea.