Rudder
A rudder is a primary control surface used to steer a
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.
Although some[a] classify a steering oar as a rudder, others[b] 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, was better fit for larger vessels on ocean-going travel, and first appeared in ancient China during the 1st century AD.[7][9][10][11][12] In regards to the ancient Phoenician (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.[13]
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
Rowing oars set aside for steering appeared on large Egyptian vessels long before the time of
In Iran, 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
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.[21] The strength of the steering oar lay in its combination of effectiveness, adaptability and simpleness.[21] Roman quarter steering oar mounting systems survived mostly intact through the medieval period.[21]
By the first half of the 1st century AD, steering gear mounted on the stern were also quite common in Roman river and harbour craft as proved from reliefs and archaeological finds (Zwammerdam, Woerden 7). A tomb plaque of Hadrianic age shows a harbour tug boat in Ostia with a long stern-mounted oar for better leverage.[22] The boat already featured a spritsail, adding to the mobility of the harbour vessel.[23] Further attested Roman uses of stern-mounted steering oars includes barges under tow, transport ships for wine casks, and diverse other ship types.[24][25][26] A large river barge found at the mouth of the Rhine near Zwammerdam featured a large steering gear mounted on the stern.[27][28] According to new research, the advanced Nemi ships, the palace barges of emperor Caligula (37-41 AD), may have featured 14 m long rudders.[29]
Sternpost-mounted rudder
Ancient China
The world's oldest known depiction of a sternpost-mounted rudder can be seen on a pottery model of a Chinese
Chinese rudders are attached to the hull by means of wooden jaws or sockets,[33] while typically larger ones were suspended from above by a rope tackle system so that they could be raised or lowered into the water.[33] 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 are known from various travellers to China, such as Ibn Battuta of Tangier, Morocco and Marco Polo of Venice, Italy. The later Chinese encyclopedist Song Yingxing (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.[34]
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.[30]
Ancient India
A Chandraketugarh (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.[35][36]
Medieval Near East
- 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.[38]
Medieval Europe
Oars mounted on the side of ships evolved into quarter steering oars, which were used from antiquity until the end of the Middle Ages in Europe. 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 and gudgeon attachment. While steering oars were found in Europe on a wide range of vessels since Roman times, including light war galleys in Mediterranean,[9][30] the oldest known depiction of a pintle-and-gudgeon rudder can be found on church carvings of Zedelgem and Winchester dating to around 1180.[9][30]
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.[39] 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.[40] From the Age of Discovery onwards, European ships with pintle-and-gudgeon rudders sailed successfully on all seven seas.[40]
Historians like Joseph Needham hold that the stern-mounted rudder was transferred from China to Europe and the Islamic world during the Middle Ages.[7][8][30]
Modern rudders
Conventional rudders have been essentially unchanged since
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.[44]
Rudder control
This section is missing information about other types of steering gear, such as rotary type steering gear.(June 2021) |
Large ships (over 10,000 ton gross tonnage) have requirements on rudder turnover time. To comply with this, high torque rudder controls are employed.[45] 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.[46]
Aircraft rudders
On an aircraft, a rudder is the directional
Unlike a ship, both
Another technique for yaw control, used on some tailless aircraft and flying wings, 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
- Ship's wheel – Mechanism used to steer a ship or other watercraft
- Azipod – Electric drive azimuth thruster
- Kitchen rudder – Type of directional propulsion system for vessels
- Pleuger rudder – Thruster assisted ship's rudder
- Schilling rudder – Low aspect ratio rudder with endplates
- Voith Schneider propeller – Perpendicular axis marine propulsion system
Notes
- Oxford Dictionary of English Etymology[6]
- ^ Joseph Needham, Lefèbre des Noëttes, K.S. Tom, Chung Chee Kit, S.A.M. Adshead, John K. Fairbank, Merle Goldman, Frank Ross, and Leo Block.[7][8][9]
Footnotes
- ^ Encyclopædia Britannica 2006 Ultimate Reference Suite DVD
- ^ 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
- ^ Lawrence V. Mott, The Development of the Rudder, A.D. 100-1600: A Technological Tale, Thesis May 1991, Texas A&M University, p.2f., 92
- ^ Timothy J. Runyan: “Review of The Development of the Rudder: A Technological Tale“, Speculum, Vol. 74, No. 4, (1999), pp. 1096-1098 (1098)
- ^ The Concise Oxford Dictionary of English Etymology
- ^ ISBN 0-8248-1285-9. Page 103–104.
- ^ a b c d Needham, Volume 4, Part 3, 649-650.
- ^ ISBN 0-312-22565-2. Page 156.
- ^ a b c 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.
- ISBN 0-674-11673-9. Page 93.
- ISBN 1-55750-209-9. Page 123.
- ISBN 1-55750-209-9. 8–9.
- ^ a b William F. Edgerton: "Ancient Egyptian Steering Gear", The American Journal of Semitic Languages and Literatures, Vol. 43, No. 4. (1927), pp. 255
- ^ William F. Edgerton: "Ancient Egyptian Steering Gear", The American Journal of Semitic Languages and Literatures, Vol. 43, No. 4. (1927), pp. 257
- ^ William F. Edgerton: "Ancient Egyptian Steering Gear", The American Journal of Semitic Languages and Literatures, Vol. 43, No. 4. (1927), pp. 260
- ISBN 978-977-424-504-6, p.92f.
- ^ Mohamed Ata: “Egypt from Past to Present. Through the Eyes of an Egyptian”, Cairo 2007, p.68
- Herodot: Histories, 2.96
- ^ William F. Edgerton: “Ancient Egyptian Steering Gear”, The American Journal of Semitic Languages and Literatures, Vol. 43, No. 4. (1927), pp. 263
- ^ a b c Lawrence V. Mott, The Development of the Rudder, A.D. 100-1600: A Technological Tale, Thesis May 1991, Texas A&M University, p.1
- ^ 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)
- ^ Lionel Casson, Harbour and River Boats of Ancient Rome, The Journal of Roman Studies, Vol. 55, No. ½, Parts 1 and 2. (1965), pp. 35 (Pl. I); 36, Fn.43 (Pl.II,1)
- ^ 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.
- ISBN 0-8018-5130-0, S.XXVIII, 336f.; Fig.193
- ISBN 3-7774-3440-X, p.183, 203 (Fig.266)
- ^ 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.
- ^ Deutschlandfunk: Römische Schiffsversuchsanstalt in den Albaner Bergen
- ^ ISBN 0-415-02635-0. Page 191.
- ^ a b Fairbank, 192.
- ISBN 0-313-29212-4. Page 42.
- ^ a b Needham, Volume 4, Part 3, 362.
- ^ Needham, Volume 4, Par634.
- ISBN 978-1-317-79342-7.
- JSTOR 43732572.
- ^ a b Lawrence V. Mott, p.93
- ^ Lawrence V. Mott, p.92f.
- ^ Lawrence V. Mott, The Development of the Rudder, A.D. 100-1600: A Technological Tale, Thesis May 1991, Texas A&M University, S.2, 92f.
- ^ a b Lawrence V. Mott, The Development of the Rudder, A.D. 100-1600: A Technological Tale, Thesis May 1991, Texas A&M University, S.118f.
- ISBN 0-7195-4636-2.
- ISBN 9780863410475. Retrieved 2015-01-10.
- ^ Osmotech UK on Uses and advantages of bow thrusters Archived July 26, 2013, at the Wayback Machine
- ^ "Barrel Type Rudder Makes Quicker Turns" Popular Mechanics, October 1934, bottom-right pg.495
- ISBN 978-0-08-056009-0.
- ^ "Understanding Steering Gear in Ships". Marine Insight. 2019-02-20. Retrieved 2021-06-03.
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. ISBN 0-674-01828-1
- Needham, Joseph (1986). Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 3, Civil Engineering and Nautics. Taipei: Caves Books Ltd.