Don't you think that it is a bit weird how in a pirate game you can't really be a pirate at all because there are no ships to steal from. Of course there are other pirates but stealing from them is not really piracy. And I don't think there will be that many people doing the trading missions so being a pirate in this game would be practically impossible. Additionally you don't encounter other pirates that often so even if you argue that stealing from pirates is piracy it is still not the main point of the game.
At the moment one of the main parts of the game is digging up treasure whereas real pirates are the ones who put the treasure there. It would make sense if we were the ones trying to hide our treasure from the other players while acquiring it by stealing from NPC ships. It wouldn't be that hard for you to implement this. You already have relatively good AI you just need to make NPCs that can use different parts of a ship. It's enough to teach them to move from outpost to outpost or from map edge to map edge.
Another fun mechanic would be NPC pirate hunters and escorts for the NPC ships that will start to appear more and more as you steal from the NPC trading ships.
In general you want the game to be about piracy but there is barely any piracy in it. You already have all the game mechanics to transform it into a pirate game. I don't want you to remove the concept of digging up treasure from past pirates but it would be cool of you could dig up the treasure of other players as well (maybe by limiting the amount of gold a player can carry and if he exceeds it he can put it in a chest and hide it somewhere). Creating the riddle type instructions for hiding treasure wouldn't be that hard since it looks like you are already automatically generating those so you can simply let the player select which objects in the world the players should interact with to solve the riddle and find the treasure. Of course you will have to add a few more things to the game like map storage on a ship and in the inventory so that if you kill a player carrying a map that shows where a treasure hidden by a player is he drops it or you can steal it from his ship. You will also have to keep the hidden chests always in the server where the player holding the map is. There should probably also be a place at the outposts where you will have to deliver the maps to claim them so that people wouldn't be able to just jump on your ship, take your maps and instantly disconnect leaving you with no way of reclaiming them.
Sorry for the long post.
