There are four ship types in Patrician 3: Snaikka, Crayer, Cog and Hulk.
Snaikkas and Crayers are light and fast boats, but their cargo capacity is much lower than that of heavier ships. They are the only ships that are capable of sailing on a river, which makes them necessary for trading with towns such as Novgorod.
Cogs and Hulks can carry very large amounts of cargo, cannons and sailors. They can withstand much more damage as well, which is a useful trait for warships or expedition convoys.
Different ship types have different speed and maneuverability, which affect their behaviour in travelling and in naval combat.
Hulks can only be built by experienced shipyards, and they are generally not available in the beginning of the game (unless you start in year 1380 or later). Pirates get access to Hulks much earlier, so it is possible to capture extended Hulks before they can be ordered at a shipyard.
Experienced shipyards can also build improved versions of the same ship types. These ships have higher cargo capacity () and more hitpoints, but their construction cost is slightly higher.
Ships can be upgraded to add or increase available weapon slots, and to improve their damage resistance. Level 1 is the regular version, while Level 2 and Level 3 extensions increase the ship's hitpoints and weapon slots, but reduce cargo capacity. Ships can be improved at any shipyard or Repair Dock.