Just a thought, but what if your ship floated lower in the water the more weight (chests/coops/etc) you have on board, so the longer you go and the more stuff you collect without docking at an outpost to "cash out" the more of your ship sails below the water level?
This would do three things:
- make it a more obvious target to a keen eyed enemy pirate who notices how low you're sailing
- make it sail and turn a bit slower than normal making the biggest juiciest targets easier to catch up to!
- place an artificial cap to how much loot you can carry on each type of ship as past a certain weight limit your ship will just begin to take on water and eventually sink even without any holes in it.
