Rudder is used to manipulate and control the course of the ship, generally located in the stern, also known as the stern rudder, it is a major invention of China's shipbuilding technology. According to functions, rudders are divided into balance rudder, elevator and perforated rudder. According to the use, ship rudders can be divided into river ship rudder and sea ship rudder.
From experience and unearthed cultural relics, we can see that the rudder evolved from the oar. The propeller can control the course when it is used as a propulsion tool. However, when many rowers rowed, it was very difficult to propel and control the course, so a special rower was set up to control the course.