I don't think there would be enough water to hold all these boats seeing as how some are cheap enough for more than half a world to get. So would this include an increase the amount of water in the game? Possibly a bit more beautifying too. And also I don't think they had metal made ships back in the day... so possibly change the boats materials to logs and get rid of the metal boats. For instance have willow, maple, yew, etc... boats instead of bronze, iron steel, etc.?