ิีิbut it was the chin under the han dynasty that added a crucial technological development that advanced ship design during the 1 century ad,they invented the wooden rudder which was used for steering a rudder is basically a flat sheet of wood,used for steering that is connected to a boat via a hinge (or pivot) cables connect to the rudder,pushing or pulling it to the left or right,thereby turning the ship the stern-mounted rudder replaced the oar steering system as it required less manpower and did not interfere with the operation of sails