Another name for the tiller, by which the rudder of small sailing vessels, such as yachts, dinghies, etc., is moved. It also the general term associated with orders connected with the steering of a ship, so that the man who is steering is known as the helmsman.
After the replacement of the original steering oar by the rudder, steering by tiller, aided in larger ships by the whipstaff, was the general form of steering for all ships, and although the tiller gave way early in the 18th century to the steering wheel in ships of any size, the original helm orders (applicable to the tiller) remained in operation. The steering wheel is connected to the rudder so that the direction of turn is the same as the movement of the rudder, i.e. when the wheel is put over to starboard, the rudder moves to starboard and the ship's head moves the same way. The reverse is the case with the tiller, which moves in the opposite way to the rudder: when the tiller is put to starboard the rudder moves to port and the ship's head swings to port as well.
For some three centuries all helm orders given in ships remained applicable to the tiller, and an order from the navigator of a ship to a helmsman of, for example, ‘port 20’ meant that the helmsman put the wheel over 20° to starboard, the equivalent direction of moving the tiller 20° to port, and the rudder and the ship's head moved to starboard. This practice was universal until after the First World War (1914–18), when some nations began to adopt the practice of relating helm orders to the rudder and not to the tiller, so that an order of ‘starboard 20’, for instance, meant turning the wheel, the rudder, and the ship's head all to starboard. By the mid-1930s all maritime nations had adopted this practice, which removed the anomaly of a navigator giving the order ‘port’ when he wanted to turn the ship to starboard, and vice versa. See also steering gear.