![Olympic stern and rudder](https://upload.wikimedia.org/wikipedia/commons/3/3c/Olympic_stern_and_rudder.jpg)
A rudder is a primary control surface used to steer a
ship
A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research, and fishing. Ships are generally distinguished ...
,
boat
A boat is a watercraft of a large range of types and sizes, but generally smaller than a ship, which is distinguished by its larger size, shape, cargo or passenger capacity, or its ability to carry boats.
Small boats are typically found on inl ...
,
submarine
A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely op ...
,
hovercraft
A hovercraft, also known as an air-cushion vehicle or ACV, is an amphibious Craft (vehicle), craft capable of travelling over land, water, mud, ice, and other surfaces.
Hovercraft use blowers to produce a large volume of air below the hull ...
,
aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...
, or other vehicle that moves through a
fluid
In physics, a fluid is a liquid, gas, or other material that continuously deforms (''flows'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are substances which cannot resist any shear ...
medium (generally
air
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing for ...
or
water
Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...
). On an aircraft the rudder is used primarily to counter
adverse yaw Adverse yaw is the natural and undesirable tendency for an aircraft to yaw in the opposite direction of a roll. It is caused by the difference in lift and drag of each wing. The effect can be greatly minimized with ailerons deliberately designed to ...
and
p-factor
P-factor, also known as asymmetric blade effect and asymmetric disc effect, is an aerodynamic phenomenon experienced by a moving propeller,) where the propeller's center of thrust moves off-center when the aircraft is at a high angle of attack. ...
and is not the primary control used to turn the airplane. A rudder operates by redirecting the fluid past the
hull or
fuselage
The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft t ...
, thus imparting a turning or
yawing motion to the craft. In basic form, a rudder is a flat plane or sheet of material attached with
hinge
A hinge is a mechanical bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation: all other ...
s to the craft's
stern
The stern is the back or aft-most part of a ship or boat, technically defined as the area built up over the sternpost, extending upwards from the counter rail to the taffrail. The stern lies opposite the bow, the foremost part of a ship. Ori ...
, tail, or after end. Often rudders are shaped so as to minimize
hydrodynamic
In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases. It has several subdisciplines, including ''aerodynamics'' (the study of air and other gases in motion) and ...
or
aerodynamic drag
In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fl ...
. On simple
watercraft
Any vehicle used in or on water as well as underwater, including boats, ships, hovercraft and submarines, is a watercraft, also known as a water vessel or waterborne vessel. A watercraft usually has a propulsive capability (whether by sail, ...
, a
tiller
A tiller or till is a lever used to steer a vehicle. The mechanism is primarily used in watercraft, where it is attached to an outboard motor, rudder post or stock to provide leverage in the form of torque for the helmsman to turn the rudder. ...
—essentially, a stick or pole acting as a lever arm—may be attached to the top of the rudder to allow it to be turned by a
helmsman
A helmsman or helm (sometimes driver) is a person who steering, steers a ship, sailboat, submarine, other type of maritime vessel, or spacecraft. The rank and seniority of the helmsman may vary: on small vessels such as fishing vessels and yacht ...
. In larger vessels, cables,
pushrod
A valvetrain or valve train is a mechanical system that controls the operation of the intake and exhaust valves in an internal combustion engine. The intake valves control the flow of air/fuel mixture (or air alone for direct-injected engines) ...
s, or hydraulics may be used to link rudders to steering wheels. In typical aircraft, the rudder is operated by pedals via mechanical linkages or hydraulics.
History of the rudder
Generally, a rudder is "part of the steering apparatus of a boat or ship that is fastened outside the hull", that is denoting all different types of oars, paddles, and rudders.
[rudder.Encyclopædia Britannica. Retrieved August 8, 2008, from ]Encyclopædia Britannica 2006 Ultimate Reference Suite DVD
An encyclopedia (American English) or encyclopædia (British English) is a reference work or compendium providing summaries of knowledge either general or special to a particular field or discipline. Encyclopedias are divided into articles ...
More specifically, the steering gear of ancient vessels can be classified into side-rudders and stern-mounted rudders, depending on their location on the ship. A third term,
steering oar
The steering oar or steering board is an over-sized oar or board, to control the direction of a ship or other watercraft prior to the invention of the rudder.
It is normally attached to the starboard side in larger vessels, though in smaller ...
, can denote both types. In a
Mediterranean
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the e ...
context, side-rudders are more specifically called quarter-rudders as the later term designates more exactly the place where the rudder was mounted. Stern-mounted rudders are uniformly suspended at the back of the ship in a central position.
[William F. Edgerton: “Ancient Egyptian Steering Gear”, ''The American Journal of Semitic Languages and Literatures'', Vol. 43, No. 4. (1927), pp. 255-265][R. O. Faulkner: ''Egyptian Seagoing Ships'', ''The Journal of Egyptian Archaeology'', Vol. 26. (1941), pp. 3-9]
Although some classify a
steering oar
The steering oar or steering board is an over-sized oar or board, to control the direction of a ship or other watercraft prior to the invention of the rudder.
It is normally attached to the starboard side in larger vessels, though in smaller ...
as a rudder, others argue that the steering oar used in ancient Egypt and Rome was not a true rudder and define only the stern-mounted rudder used in ancient
Han dynasty China as a true rudder. The steering oar has the capacity to interfere with the handling of the sails (limiting any potential for long ocean-going voyages) while it was fit more for small vessels on narrow, rapid-water transport; the rudder did not disturb the handling of the sails, took less energy to operate by its
helmsman
A helmsman or helm (sometimes driver) is a person who steering, steers a ship, sailboat, submarine, other type of maritime vessel, or spacecraft. The rank and seniority of the helmsman may vary: on small vessels such as fishing vessels and yacht ...
, was better fit for larger vessels on ocean-going travel, and first appeared in
ancient China
The earliest known written records of the history of China date from as early as 1250 BC, from the Shang dynasty (c. 1600–1046 BC), during the reign of king Wu Ding. Ancient historical texts such as the '' Book of Documents'' (early chapte ...
during the 1st century AD.
[Tom, K.S. (1989). ''Echoes from Old China: Life, Legends, and Lore of the Middle Kingdom''. Honolulu: The Hawaii Chinese History Center of the University of Hawaii Press. . Page 103–104.][Adshead, Samuel Adrian Miles. (2000). ''China in World History''. London: MacMillan Press Ltd. New York: St. Martin's Press. . Page 156.][Needham, Joseph. (1986). ''Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 3, Civil Engineering and Nautics''. Taipei: Caves Books Ltd. Pages 627–628.] In regards to the ancient
Phoenicia
Phoenicia () was an ancient thalassocratic civilization originating in the Levant region of the eastern Mediterranean, primarily located in modern Lebanon. The territory of the Phoenician city-states extended and shrank throughout their histor ...
n (1550–300 BC) use of the steering oar without a rudder
in the Mediterranean, Leo Block (2003) writes:
A single sail tends to turn a vessel in an upwind or downwind direction, and rudder action is required to steer a straight course. A steering oar was used at this time because the rudder had not yet been invented. With a single sail, a frequent movement of the steering oar was required to steer a straight course; this slowed down the vessel because a steering oar (or rudder) course correction acts as a brake. The second sail, located forward, could be trimmed to offset the turning tendency of the mainsail and minimize the need for course corrections by the steering oar, which would have substantially improved sail performance.
The steering oar or steering board is an oversized oar or board to control the direction of a ship or other watercraft prior to the invention of the rudder. It is normally attached to the starboard side in larger vessels, though in smaller ones it is rarely if ever, attached.
Steering oar/gear
Ancient Egypt
![Maler der Grabkammer des Menna 013](https://upload.wikimedia.org/wikipedia/commons/c/c2/Maler_der_Grabkammer_des_Menna_013.jpg)
Rowing oars set aside for steering appeared on large Egyptian vessels long before the time of
Menes
Menes (fl. c. 3200–3000 BC; ; egy, mnj, probably pronounced *; grc, Μήνης) was a pharaoh of the Early Dynastic Period of ancient Egypt credited by classical tradition with having united Upper and Lower Egypt and as the founder of the ...
(3100 BC).
[William F. Edgerton: "Ancient Egyptian Steering Gear", ''The American Journal of Semitic Languages and Literatures'', Vol. 43, No. 4. (1927), pp. 255] In the
Old Kingdom
In ancient Egyptian history, the Old Kingdom is the period spanning c. 2700–2200 BC. It is also known as the "Age of the Pyramids" or the "Age of the Pyramid Builders", as it encompasses the reigns of the great pyramid-builders of the Fourth ...
(2686 BC – 2134 BC) as many as five steering oars are found on each side of passenger boats.
The
tiller
A tiller or till is a lever used to steer a vehicle. The mechanism is primarily used in watercraft, where it is attached to an outboard motor, rudder post or stock to provide leverage in the form of torque for the helmsman to turn the rudder. ...
, at first a small pin run through the stock of the steering oar, can be traced to the fifth dynasty (2504–2347 BC).
[William F. Edgerton: "Ancient Egyptian Steering Gear", ''The American Journal of Semitic Languages and Literatures'', Vol. 43, No. 4. (1927), pp. 257] Both the tiller and the introduction of an upright steering post abaft reduced the usual number of necessary steering oars to one each side.
[William F. Edgerton: "Ancient Egyptian Steering Gear", ''The American Journal of Semitic Languages and Literatures'', Vol. 43, No. 4. (1927), pp. 260] Single steering oars put on the stern can be found in a number of tomb models of the time, particularly during the
Middle Kingdom when tomb reliefs suggests them commonly employed in
Nile
The Nile, , Bohairic , lg, Kiira , Nobiin language, Nobiin: Áman Dawū is a major north-flowing river in northeastern Africa. It flows into the Mediterranean Sea. The Nile is the longest river in Africa and has historically been considered ...
navigation. The first literary reference appears in the works of the
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
historian
Herodotus
Herodotus ( ; grc, , }; BC) was an ancient Greek historian and geographer from the Greek city of Halicarnassus, part of the Persian Empire (now Bodrum, Turkey) and a later citizen of Thurii in modern Calabria ( Italy). He is known f ...
(484-424 BC), who had spent several months in
Egypt
Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Mediter ...
: "They make one rudder, and this is thrust through the
keel
The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. As the laying down of the keel is the initial step in the construction of a ship, in Br ...
", probably meaning the crotch at the end of the keel (as depicted in the "Tomb of Menna").
In
Iran
Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...
, oars mounted on the side of ships for steering are documented from the 3rd millennium BCE in artwork, wooden models, and even remnants of actual boats.
Ancient Rome
![Rudder of a Roman Boat (RG Museum Koeln, Germany)](https://upload.wikimedia.org/wikipedia/commons/4/40/Rudder_of_a_Roman_Boat_%28RG_Museum_Koeln%2C_Germany%29.JPG)
Roman navigation used sexillie quarter steering oars that went in the Mediterranean through a long period of constant refinement and improvement, so that by Roman times ancient vessels reached extraordinary sizes.
[Lawrence V. Mott, The Development of the Rudder, A.D. 100-1600: A Technological Tale, Thesis May 1991, Texas A&M University, p.1] The strength of the steering oar lay in its combination of effectiveness, adaptability and simpleness.
Roman quarter steering oar mounting systems survived mostly intact through the medieval period.
By the first half of the 1st century AD, steering gear mounted on the stern were also quite common in
Roman
Roman or Romans most often refers to:
*Rome, the capital city of Italy
*Ancient Rome, Roman civilization from 8th century BC to 5th century AD
*Roman people, the people of ancient Rome
*''Epistle to the Romans'', shortened to ''Romans'', a letter ...
river and harbour craft as proved from
relief
Relief is a sculptural method in which the sculpted pieces are bonded to a solid background of the same material. The term ''relief'' is from the Latin verb ''relevo'', to raise. To create a sculpture in relief is to give the impression that the ...
s and archaeological finds (
Zwammerdam
Zwammerdam is a village in the Dutch province of South Holland along Oude Rijn river. It is a part of the municipality of Alphen aan den Rijn, and lies about 6 km southeast of Alphen aan de Rijn. The name derives from a dam built in the Rhi ...
,
Woerden
Woerden () is a city and a municipality in central Netherlands. Due to its central location between Amsterdam, Rotterdam, The Hague, and Utrecht, and the fact that it has rail and road connections to those cities, it is a popular town for commu ...
7). A tomb plaque of
Hadrian
Hadrian (; la, Caesar Trâiānus Hadriānus ; 24 January 76 – 10 July 138) was Roman emperor from 117 to 138. He was born in Italica (close to modern Santiponce in Spain), a Roman ''municipium'' founded by Italic settlers in Hispania B ...
ic age shows a harbour tug boat in
Ostia with a long stern-mounted oar for better leverage.
[Lionel Casson: ''Harbour and River Boats of Ancient Rome'', ''The Journal of Roman Studies'', Vol. 55, No. 1/2, Parts 1 and 2 (1965), pp. 31-39 (plate 1)] The boat already featured a
spritsail
The spritsail is a four-sided, fore-and-aft sail that is supported at its highest points by the mast and a diagonally running spar known as the sprit. The foot of the sail can be stretched by a boom or held loose-footed just by its sheets. A spr ...
, adding to the mobility of the harbour vessel. Further attested Roman uses of stern-mounted steering oars includes barges under tow, transport ships for wine casks, and diverse other ship types.
[Lawrence V. Mott, The Development of the Rudder, A.D. 100-1600: A Technological Tale, Thesis May 1991, Texas A&M University, p.84, 95f.][Lionel Casson: “Ships and Seamanship in the Ancient World”, , S.XXVIII, 336f.; Fig.193][Tilmann Bechert: Römisches Germanien zwischen Rhein und Maas. Die Provinz Germania inferior, Hirmer, München 1982, , p.183, 203 (Fig.266)] A large river barge found at the mouth of the Rhine near
Zwammerdam
Zwammerdam is a village in the Dutch province of South Holland along Oude Rijn river. It is a part of the municipality of Alphen aan den Rijn, and lies about 6 km southeast of Alphen aan de Rijn. The name derives from a dam built in the Rhi ...
featured a large steering gear mounted on the stern.
[M. D. de Weerd: Ships of the Roman Period at Zwammerdam / Nigrum Pullum, Germania Inferior, in: Roman Shipping and Trade: Britain and the Rhine Provinces. (The Council for) British Archaeology, Research Report 24, 1978, 15ff.][M. D. de Weerd: Römerzeitliche Transportschiffe und Einbäume aus Nigrum Pullum / Zwammerdam, in: Studien zu den Militärgrenzen Roms II (1977), 187ff.] According to new research, the advanced
Nemi ships
The Nemi ships were two ships, one larger than the other, built under the reign of the Roman emperor Caligula in the 1st century CE on Lake Nemi. Although the purpose of the ships is only speculated upon, the larger ship was an elaborate floa ...
, the palace barges of emperor
Caligula
Gaius Julius Caesar Augustus Germanicus (31 August 12 – 24 January 41), better known by his nickname Caligula (), was the third Roman emperor, ruling from 37 until his assassination in 41. He was the son of the popular Roman general Germanicu ...
(37-41 AD), may have featured 14 m long rudders.
Sternpost-mounted rudder
Ancient China
![Eastern Han pottery boat](https://upload.wikimedia.org/wikipedia/commons/f/fc/Eastern_Han_pottery_boat.JPG)
The world's oldest known depiction of a sternpost-mounted rudder can be seen on a pottery model of a Chinese
junk dating from the 1st century AD during the
Han Dynasty
The Han dynasty (, ; ) was an imperial dynasty of China (202 BC – 9 AD, 25–220 AD), established by Liu Bang (Emperor Gao) and ruled by the House of Liu. The dynasty was preceded by the short-lived Qin dynasty (221–207 BC) and a warr ...
, predating their appearance in the West by a thousand years.
In China, miniature models of ships that feature steering oars have been dated to the
Warring States period
The Warring States period () was an era in History of China#Ancient China, ancient Chinese history characterized by warfare, as well as bureaucratic and military reforms and consolidation. It followed the Spring and Autumn period and concluded ...
(c. 475–221 BC).
Sternpost-mounted rudders started to appear on Chinese ship models starting in the 1st century AD.
However, the Chinese continued to use the steering oar long after they invented the rudder, since the steering oar still had practical use for inland rapid-river travel.
One of oldest known depictions of the Chinese stern-mounted rudder (''duò'' ) can be seen on a pottery model of a
junk dating from the 1st century AD, during the
Han dynasty
The Han dynasty (, ; ) was an imperial dynasty of China (202 BC – 9 AD, 25–220 AD), established by Liu Bang (Emperor Gao) and ruled by the House of Liu. The dynasty was preceded by the short-lived Qin dynasty (221–207 BC) and a warr ...
(202220 AD).
[Needham, Volume 4, Part 3, 649-650.][Fairbank, 192.] It was discovered in
Guangzhou
Guangzhou (, ; ; or ; ), also known as Canton () and alternatively romanized as Kwongchow or Kwangchow, is the capital and largest city of Guangdong province in southern China. Located on the Pearl River about north-northwest of Hong Kon ...
in an archaeological excavation carried out by the
Guangdong Provincial Museum
The Guangdong Museum () is a general museum of Cantonese art, nature, culture and history in Guangzhou.
History Old building
The Guangdong Provincial Museum was located on 215 Wenming Rd. (), in Yuexiu District, Guangzhou, on which was the o ...
and
Academia Sinica
Academia Sinica (AS, la, 1=Academia Sinica, 3=Chinese Academy; ), headquartered in Nangang, Taipei, is the national academy of Taiwan. Founded in Nanking, the academy supports research activities in a wide variety of disciplines, ranging from ...
of
Taiwan
Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the nort ...
in 1958.
Within decades, several other Han Dynasty ship models featuring rudders were found in archaeological excavations. The first solid written reference to the use of a rudder without a steering oar dates to the 5th century.
[Johnstone, Paul and Sean McGrail. (1988). ''The Sea-craft of Prehistory''. New York: Routledge. . Page 191.]
Chinese rudders are attached to the hull by means of wooden jaws or sockets,
while typically larger ones were suspended from above by a rope
tackle system so that they could be raised or lowered into the water.
[Needham, Volume 4, Part 3, 362.] Also, many junks incorporated "fenestrated rudders" (rudders with holes in them, supposedly allowing for better control). Detailed descriptions of Chinese junks during the
Middle Ages
In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire a ...
are known from various travellers to China, such as
Ibn Battuta
Abu Abdullah Muhammad ibn Battutah (, ; 24 February 13041368/1369),; fully: ; Arabic: commonly known as Ibn Battuta, was a Berbers, Berber Maghrebi people, Maghrebi scholar and explorer who travelled extensively in the lands of Afro-Eurasia, ...
of
Tangier
Tangier ( ; ; ar, طنجة, Ṭanja) is a city in northwestern Morocco. It is on the Moroccan coast at the western entrance to the Strait of Gibraltar, where the Mediterranean Sea meets the Atlantic Ocean off Cape Spartel. The town is the cap ...
,
Morocco
Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to ...
and
Marco Polo
Marco Polo (, , ; 8 January 1324) was a Venetian merchant, explorer and writer who travelled through Asia along the Silk Road between 1271 and 1295. His travels are recorded in ''The Travels of Marco Polo'' (also known as ''Book of the Marv ...
of
Venice
Venice ( ; it, Venezia ; vec, Venesia or ) is a city in northeastern Italy and the capital of the Veneto Regions of Italy, region. It is built on a group of 118 small islands that are separated by canals and linked by over 400 ...
,
Italy
Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...
. The later Chinese encyclopedist
Song Yingxing
Song Yingxing (Traditional Chinese: 宋應星; Simplified Chinese: 宋应星; Wade Giles: Sung Ying-Hsing; 1587-1666 AD) was a Chinese scientist and encyclopedist who lived during the late Ming Dynasty (1368–1644). He was the author of ''Tian ...
(1587–1666) and the 17th-century European traveler Louis Lecomte wrote of the junk design and its use of the rudder with enthusiasm and admiration.
[Needham, Volume 4, Par634.]
![Pottery boat from Eastern Han Dynasty showing rudder](https://upload.wikimedia.org/wikipedia/commons/c/c2/Pottery_boat_from_Eastern_Han_Dynasty_showing_rudder.jpg)
Paul Johnstone and Sean McGrail state that the Chinese invented the "median, vertical and axial" sternpost-mounted rudder, and that such a kind of rudder preceded the pintle-and-gudgeon rudder found in the West by roughly a millennium.
Ancient India
A
Chandraketugarh
Chandraketugarh is a 2,500 years old archaeological site located near the Bidyadhari river, about north-east of Kolkata, India, in the district of North 24 parganas, near the township of Berachampa and the Harua Road railhead. Once it was a ...
(West Bengal) seal dated between the 1st and 3rd centuries AD depicts a steering mechanism on a ship named
''Indra of the Ocean
'' (Jaladhisakra), which indicates that it was a sea-bound vessel.
Medieval Near East
Arab
The Arabs (singular: Arab; singular ar, عَرَبِيٌّ, DIN 31635: , , plural ar, عَرَب, DIN 31635: , Arabic pronunciation: ), also known as the Arab people, are an ethnic group mainly inhabiting the Arab world in Western Asia, ...
ships also used a sternpost-mounted rudder.
[ On their ships "the rudder is controlled by two lines, each attached to a crosspiece mounted on the rudder head perpendicular to the plane of the rudder blade."][Lawrence V. Mott, p.93] The earliest evidence comes from the ''Ahsan al-Taqasim fi Marifat al-Aqalim'' ('The Best Divisions for the Classification of Regions') written by al-Muqaddasi
Shams al-Dīn Abū ʿAbd Allāh Muḥammad ibn Aḥmad ibn Abī Bakr al-Maqdisī ( ar, شَمْس ٱلدِّيْن أَبُو عَبْد ٱلله مُحَمَّد ابْن أَحْمَد ابْن أَبِي بَكْر ٱلْمَقْدِسِي), ...
in 985:
: ''The captain from the crow's nest carefully observes the sea. When a rock is espied, he shouts: "Starboard!" or 'Port!" Two youths, posted there, repeat the cry. The helmsman, with two ropes in his hand, when he hears the calls tugs one or the other to the right or left. If great care is not taken, the ship strikes the rocks and is wrecked.''
Medieval Europe
Oars mounted on the side of ships evolved into quarter steering oars, which were used from antiquity
Antiquity or Antiquities may refer to:
Historical objects or periods Artifacts
*Antiquities, objects or artifacts surviving from ancient cultures
Eras
Any period before the European Middle Ages (5th to 15th centuries) but still within the histo ...
until the end of the Middle Ages
In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire a ...
in Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
. As the size of ships and the height of the freeboards increased, quarter steering oars became unwieldy and were replaced by the more sturdy rudders with pintle
A pintle is a pin or bolt, usually inserted into a gudgeon, which is used as part of a pivot or hinge. Other applications include pintle and lunette ring for towing, and pintle pins securing casters in furniture.
Use
Pintle/gudgeon sets have ma ...
and gudgeon
A gudgeon is a socket-like, cylindrical (i.e., ''female'') fitting attached to one component to enable a pivoting or hinging connection to a second component. The second component carries a pintle fitting, the male counterpart to the gudgeon, ...
attachment. While steering oars were found in Europe on a wide range of vessels since Roman times, including light war galleys in Mediterranean, the oldest known depiction of a pintle-and-gudgeon rudder can be found on church carvings of Zedelgem
Zedelgem (; vls, Zillegem) is a municipality located in the Belgian province of West Flanders. The municipality comprises the villages of Aartrijke, Loppem, Veldegem and Zedelgem proper. On January 1, 2019, Zedelgem had a total population of 22,8 ...
and Winchester
Winchester is a City status in the United Kingdom, cathedral city in Hampshire, England. The city lies at the heart of the wider City of Winchester, a local government Districts of England, district, at the western end of the South Downs Nation ...
dating to around 1180.
While earlier rudders were mounted on the stern by the way of rudderposts or tackles, the iron hinges allowed the rudder to be attached to the entire length of the sternpost in a permanent fashion. However, its full potential could only to be realized after the introduction of the vertical sternpost and the full-rigged ship in the 14th century. From the Age of Discovery
The Age of Discovery (or the Age of Exploration), also known as the early modern period, was a period largely overlapping with the Age of Sail, approximately from the 15th century to the 17th century in European history, during which seafarin ...
onwards, European ships with pintle-and-gudgeon rudders sailed successfully on all seven seas.[Lawrence V. Mott, ''The Development of the Rudder, A.D. 100-1600: A Technological Tale'', Thesis May 1991, Texas A&M University, S.118f.](_blank)
/ref>
Historians like Joseph Needham
Noel Joseph Terence Montgomery Needham (; 9 December 1900 – 24 March 1995) was a British biochemist, historian of science and sinologist known for his scientific research and writing on the history of Chinese science and technology, in ...
hold that the stern-mounted rudder was transferred from China to Europe and the Islamic world during the Middle Ages.
Modern rudders
Conventional rudders have been essentially unchanged since Isambard Kingdom Brunel
Isambard Kingdom Brunel (; 9 April 1806 – 15 September 1859) was a British civil engineer who is considered "one of the most ingenious and prolific figures in engineering history," "one of the 19th-century engineering giants," and "one ...
introduced the balanced rudder
Balanced rudders are used by both ships and aircraft. Both may indicate a portion of the rudder surface ahead of the hinge, placed to lower the control loads needed to turn the rudder. For aircraft the method can also be applied to elevators and ...
on the SS ''Great Britain'' in 1843 and the steering engine
A steering engine is a power steering device for ships.
History
The first steering engine with feedback was installed on Isambard Kingdom Brunel's ''Great Eastern'' in 1866.
Designed by Scottish engineer John McFarlane Gray and built by George ...
in the SS ''Great Eastern'' in 1866. If a vessel requires extra maneuverability at low speeds, the rudder may be supplemented by a manoeuvring thruster
Manoeuvering thruster (bow thruster or stern thruster) is a transversal propulsion device built into, or mounted to, either the bow or stern, of a ship or boat to make it more manoeuvrable. Bow thrusters make docking easier, since they allow th ...
in the bow, or be replaced entirely by azimuth thruster
An azimuth thruster is a configuration of marine propellers placed in pods that can be rotated to any horizontal angle (azimuth), making a rudder unnecessary. These give ships better maneuverability than a fixed propeller and rudder system.
Ty ...
s.
Boat rudders details
Boat rudders may be either outboard or inboard. Outboard rudders are hung on the stern or transom. Inboard rudders are hung from a keel or skeg and are thus fully submerged beneath the hull, connected to the steering mechanism by a rudder post that comes up through the hull to deck level, often into a cockpit. Inboard keel hung rudders (which are a continuation of the aft trailing edge of the full keel) are traditionally deemed the most damage resistant rudders for off shore sailing. Better performance with faster handling characteristics can be provided by skeg hung rudders on boats with smaller fin keels.
Rudder post and mast placement defines the difference between a ketch and a yawl, as these two-masted vessels are similar. Yawls are defined as having the mizzen mast abaft (i.e. "aft of") the rudder post; ketches are defined as having the mizzen mast forward of the rudder post.
Small boat rudders that can be steered more or less perpendicular to the hull's longitudinal axis make effective brakes when pushed "hard over." However, terms such as "hard over," "hard to starboard," etc. signify a maximum-rate turn for larger vessels. Transom hung rudders or far aft mounted fin rudders generate greater moment and faster turning than more forward mounted keel hung rudders. Rudders on smaller craft can be operated by means of a tiller that fits into the rudder stock that also forms the fixings to the rudder foil. Craft where the length of the tiller could impede movement of the helm can be split with a rubber universal joint and the part adjoined the tiller termed a tiller extension. Tillers can further be extended by means of adjustable telescopic twist locking extension.
There is also the barrel type rudder, where the ship's screw is enclosed and can be swiveled to steer the vessel. Designers claim that this type of rudder on a smaller vessel will answer the helm faster.
Rudder control
Large ships (over 10,000 ton gross tonnage) have requirements on rudder turnover time. To comply with this, high torque rudder controls are employed. One commonly used system is the ram type steering gear. It employs four hydraulic rams to rotate the rudder stock (rotation axis), in turn rotating the rudder.
Aircraft rudders
On an aircraft, a rudder is the directional control surface along with the rudder-like elevator
An elevator or lift is a wire rope, cable-assisted, hydraulic cylinder-assisted, or roller-track assisted machine that vertically transports people or freight between floors, levels, or deck (building), decks of a building, watercraft, ...
(usually attached to the horizontal tail structure, if not a slab elevator) and ailerons
An aileron (French for "little wing" or "fin") is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in Flight dynamics, roll (or ...
(attached to the wings) that control pitch and roll, respectively. The rudder is usually attached to the fin
A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. Fin ...
(or vertical stabilizer
A vertical stabilizer or tail fin is the static part of the vertical tail of an aircraft. The term is commonly applied to the assembly of both this fixed surface and one or more movable rudders hinged to it. Their role is to provide control, sta ...
), which allows the pilot to control yaw about the vertical axis, i.e., change the horizontal direction in which the nose is pointing.
Unlike a ship, both aileron
An aileron (French for "little wing" or "fin") is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll (or movement around ...
and rudder controls are used together to turn an aircraft, with the ailerons imparting roll and the rudder imparting yaw and also compensating for a phenomenon called adverse yaw Adverse yaw is the natural and undesirable tendency for an aircraft to yaw in the opposite direction of a roll. It is caused by the difference in lift and drag of each wing. The effect can be greatly minimized with ailerons deliberately designed to ...
. A rudder alone will turn a conventional fixed-wing aircraft, but much more slowly than if ailerons are also used in conjunction. Sometimes pilots may intentionally operate the rudder and ailerons in opposite directions in a maneuver called a slip
Slip or SLIP may refer to:
Science and technology Biology
* Slip (fish), also known as Black Sole
* Slip (horticulture), a small cutting of a plant as a specimen or for grafting
* Muscle slip, a branching of a muscle, in anatomy
Computing and ...
or sideslip. This may be done to overcome crosswinds and keep the fuselage in line with the runway, or to lose altitude by increasing drag, or both.
Another technique for yaw control, used on some tailless aircraft
In aeronautics, a tailless aircraft is an aircraft with no other horizontal aerodynamic surface besides its main wing. It may still have a fuselage, vertical tail fin (vertical stabilizer), and/or vertical rudder.
Theoretical advantages of the ...
and flying wing
A flying wing is a tailless fixed-wing aircraft that has no definite fuselage, with its crew, payload, fuel, and equipment housed inside the main wing structure. A flying wing may have various small protuberances such as pods, nacelles, blis ...
s, is to add one or more drag-creating surfaces, such as split ailerons, on the outer wing section. Operating one of these surfaces creates drag on the wing, causing the plane to yaw in that direction. These surfaces are often referred to as drag rudders.
See also
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Notes
Footnotes
References
Lawrence V. Mott, ''The Development of the Rudder, A.D. 100-1600: A Technological Tale'', Thesis May 1991, Texas A&M University
*Fairbank, John King and Merle Goldman (1992). ''China: A New History; Second Enlarged Edition'' (2006). Cambridge: MA; London: The Belknap Press of Harvard University Press.
*Needham, Joseph (1986). ''Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 3, Civil Engineering and Nautics''. Taipei: Caves Books Ltd.
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