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A tiller or till is a lever attached to a rudder post (American terminology) or rudder stock (English terminology) of a boat that provides leverage for the helmsman to turn the rudder. The tiller is normally used by the helmsman directly pulling or pushing it, but it may also be moved remotely using tiller lines.
Rapid or excessive movement of the tiller results in an increase in drag and will result in braking or slowing the boat. In steering a boat, the tiller is always moved in the direction opposite of which the bow of the boat is to move. If the tiller is moved to port side (left), the bow will turn to starboard (right). If the tiller is moved to starboard (right), the bow will turn port (left). Sailing students often learn the alliterative phrase "Tiller Towards Trouble" to remind them of how to steer.
As the size of boat increases the force needed to control the rudder via a tiller becomes excessive. In the 21st century, a steering wheel tends to be used instead of a tiller on new boats with an overall length in excess of approximately 10 metres, except on narrowboats on English canals, where boats up to 22 metres long and steered by a tiller are being built. Although the wheel replaced the tiller as the direct means of controlling the vessel the tiller was still present, connected as before to the top of the rudder. However it was now moved by mechanical means controlled by a wheel (by ropes or cables on smaller vessels and ultimately by a hydraulically-controlled steam engine on large steamships).
In modern boats emergency tillers are often carried in case the steering wheel on a vessel fails to operate.
Until the current international standards were applied in the 1930s, it was common for steering orders on ships to be given as "Tiller Orders", i.e. the order given dictated which side of the vessel the tiller was to be moved. Since the tiller's movement is reversed at the rudder, orders were seemingly given "the wrong way round". For example, to turn a ship to port (its left side), the helmsman would be given the order "starboard helm" or "x degrees starboard". The ship's tiller was then put over to the side ordered, turning the rudder to the vessel's port side, producing a turn to port.
When large steamships appeared in the late 19th century with telemotors hydraulically connecting the wheel on the bridge to the steering gear at the stern, the practice continued. However the helmsman was now no longer directly controlling the tiller, and the ship's wheel was simply turned in the desired direction (turn the wheel to port and the ship will go to port). Tiller Orders remained however: although many maritime nations had abandoned the convention by the end of the 19th century, Britain retained it until 1933 and the U.S. merchant marine until 1935. One of the reasons for this system continuing, apart from it being a long-established maritime tradition, was that it provided consistency- regardless of whether a vessel was steered directly by the tiller or remotely by a wheel every vessel had a tiller of some sort and so a tiller order remained true for any vessel.
A well-known and often-depicted example occurred on the RMS Titanic in 1912 when she collided with an iceberg. The iceberg appeared directly in front of the Titanic. Her officer-of-the-watch, First Officer William Murdoch, decided to attempt to clear the berg by swinging the ship to its port side. He ordered 'Hard-a-Starboard', which was a Tiller Order. The helmsman turned the wheel to port as far as it would go. The Titanic's steering gear pushed the tiller over to the starboard side of the ship, causing the rudder to swing over to port, causing the vessel to turn port. These actions are faithfully portrayed in the 1997 film of the disaster. Although frequently described as an error, it is correct.
Although this system seems confusing and contradictory today, to generations of sailors trained on sailing vessels with tiller steering it seemed perfectly logical and was instinctively understood by all seafarers. Only when new generations of sailors trained on ships with wheel-and-tiller steering came into the industry was the system replaced.
Tillers on other vehicles
The first automobiles were steered with a tiller, but Packard introduced the steering wheel on the second car they built, in 1899. Within a decade, the steering wheel had entirely replaced the tiller in automobiles.
Arthur Constantin Krebs replaced the tiller with an inclined steering wheel for the Panhard & Levassor car he designed for the Paris-Amsterdam race which ran from the 7–13 July 1898.
Tractor-drawn ladder trucks utilize a tiller (rear steering axle) driver to control the trailer where the aerial ladder is located.
Some jetliners, such as the Boeing 737, use a tiller to steer while taxiing.