Stern-Mounted Rudder (Edited from Wikipedia)

SUMMARY

A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other conveyance that moves through a fluid medium (generally air or water). On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane. A rudder operates by redirecting the fluid past the hull (watercraft) or fuselage, 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 hinges to the craft's stern, tail, or after end.

Often rudders are shaped so as to minimize hydrodynamic or aerodynamic drag. On simple watercraft, a tiller—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. In larger vessels, cables, pushrods, 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

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.[1] 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, can denote both types. In a Mediterranean 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.

The steering oar used in ancient Egypt and Rome was not a true rudder. The stern- mounted rudder used in China, however, was; the steering oar has the capacity to interfere with 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.

1 The world's oldest known depiction of a sternpost-mounted rudder can be seen on a pottery model of a Chinese junk [“ship”] dating from the 1st century AD during the Han Dynasty, predating their appearance in the West by a thousand years. 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 limited practical use for inland rapid-river travel.

One of oldest known depictions of a stern-mounted rudder in China can be seen on a 2-foot-long tomb pottery model of a junk dating from the 1st century AD, during the Han Dynasty (202 BC-220 AD). The first solid written reference to the use of a rudder without a steering oar dates to the 5th century.

Arab 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.

In Europe

Oars mounted on the side of ships evolved into quarter rudders, 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-rudders became unwieldy and were replaced by the more sturdy stern-mounted rudders with pintle and gudgeon attachment. While stern- mounted rudders 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 and Winchester dating to around 1180.

Historically, the radical concept of the medieval pintle-and-gudgeon rudder did not come as a single invention into being. It presented rather a combination of ideas which each had been long around before: rudders mounted on the stern, iron hinges and the straight sternpost of northern European ships.

While earlier rudders were mounted on the stern by the way of rudderposts or tackles, the iron hinges allowed for the first time to attach the rudder to the entire length of the sternpost in a really 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 onwards, European ships with pintle-and-gudgeon rudders sailed successfully on all seven seas.

2 COGS

A cog (or cog-built vessels) is a type of ship that first appeared in the 10th century, and was widely used from around the 12th century on. Cogs were generally built of oak, which was an abundant timber in the Baltic region of Prussia. This vessel was fitted with a single mast and a square-rigged single sail. These vessels were mostly associated with seagoing trade in medieval Europe, especially the Hanseatic League, particularly in the Baltic Sea region. They ranged from about 15 meters to 25 meters in length (49 ft to 82 ft) with a beam of 5 to 8 meters (16 ft to 26 ft), and the largest cog ships could carry up to about 200 tons.

Cogs are first mentioned in 948 AD, in Muiden near Amsterdam. These early cogs were influenced by the Norse Knarr, which was the main trade vessel in northern Europe at the time, and probably used a steering oar, as there is nothing to suggest a stern rudder in northern Europe until about 1240.

Current archaeological evidence points to the Frisian coast or Western Jutland as the possible birthplace of this type of vessel. The transformation of the cog into a true seagoing trader came not only during the time of the intense trade between West and East, but also as a direct answer to the closure of the western entrance to the Limfjord. For centuries, Limfjord in northern Jutland offered fairly protected passage between the North Sea and the Baltic.

Due to unusual geographical conditions and strong currents, the passage was constantly filling with sand and was completely blocked by the 12th century. This change produced new challenges. Bigger ships that could not be pulled across the sand bars had to sail around the Jutland peninsula and circumnavigate the dangerous Cape Skagen to get to the Baltic. This resulted in major modifications to old ship structures, which can be observed by analyzing evolution of the earliest cog finds of Kollerup, Skagen, and Kolding.

The need for spacious and relatively inexpensive ships led to the development of the first workhorse of the Hanseatic League, the cog. The new and improved cog was no longer a simple Frisian coaster but a sturdy seagoing trader, which could cross even the most dangerous passages. Fore and stern castles would be added for defense against pirates, or to enable use of these vessels as warships, such as used at the Battle of Sluys.

3 LATEEN

A lateen (from French latine, meaning "Latin") or latin-rig is a triangular sail set on a long yard mounted at an angle on the mast, and running in a fore-and-aft direction.

Dating back to Roman navigation, the lateen became the favorite sail of the Age of Discovery, mainly because it allows a boat to tack "against the wind". It is common in the Mediterranean, the upper Nile River, and the northwestern parts of the Indian Ocean, where it is the standard rig for feluccas and dhows. The lateen is used today in a slightly different form on small recreational boats like the highly popular Sailfish and Sunfish, but is still used as a working rig by coastal fishermen in the Mediterranean.

The lateen was known from an early date on: a 2nd-century AD gravestone depicts a quadrilateral lateen sail (also known as a settee), while a 4th-century mosaic shows a triangular one which was to become the standard rig throughout the Middle Ages.

According to the Belgian maritime historian Basch, the earliest true lateen rig appears as early as the 1st century BC, in a Hellenistic wall painting found in a Hypogeum in Alexandria. The earliest archaeologically excavated lateen-rigged ship, the Yassi Ada II, dates to ca. 400 AD, with a further four being attested prior to the Arab advance to the Mediterranean. The Kelenderis ship mosaic (late 5th to early 6th century) and the Kellia ship graffito from the early 7th century complement the picture.

By the 6th century, the lateen sail had largely replaced the square sail throughout the Mediterranean, the latter almost disappearing from Mediterranean iconography until the mid-13th century. It became the standard rig of the Byzantine dromon war galley and was probably also employed by Belisarius' flagship in the 532 AD invasion of the Vandal kingdom.

After the Muslim conquests, the Arabs adopted the lateen sail by way of the Coptic [African] populace, which shared the existing Mediterranean maritime tradition and continued to provide the bulk of galley crews for Muslim-led fleets for centuries to come. This is also indicated by the fact that the terminology of the lateen among Mediterranean Arabs is derived from Greco-Roman nomenclature.

Until the 14th century, the lateen sail was employed primarily on the Mediterranean Sea, while the Atlantic and Baltic (and Indian Ocean) vessels relied on square sails. The Northern European adoption of the lateen in the Late Middle Ages was a specialized sail that was one of the technological developments in shipbuilding that made ships more maneuverable, thus, in the historian's traditional progression, permitting merchants to sail out of the Mediterranean and into the Atlantic Ocean; caravels

4 typically mounted three or more lateens. However, the great size of the lateen yardarm makes it difficult and dangerous to handle on larger ships in stormy weather, and with the development of the carrack, the lateen was restricted to the mizzen mast. In the early nineteenth century, the lateen was replaced in European ships by the driver or spanker.

A lateen rig rises better towards the wind and is far more maneuverable, allowing tacking and beating to the wind. However, it runs poorly. Thus, the Spaniards often re- rigged their vessels [with square sails] when they ventured out of the Mediterranean into the Atlantic, where the winds are constant and a square rig had the advantage.

MEDIEVAL POPULATION BOOM

In the 10th-13th centuries, agriculture expanded into the wilderness, in what has been termed the "great clearances". During the High Middle Ages, many forests and marshes were cleared and cultivated. At the same time, during the German Eastward Expansion, Germans resettled east of the Elbe and Saale rivers, in regions previously only sparsely populated by Polabian Slavs.

Crusaders expanded to the Crusader states, parts of the Iberian Peninsula were reconquered from the Moors, and the Normans colonized England and southern Italy. These movements and conquests are part of a larger pattern of population expansion and resettlement that occurred in Europe at this time.

Reasons for this expansion and colonization include an improving climate known as the Medieval warm period, which resulted in longer and more productive growing seasons; the end of the raids by Vikings, Arabs, and Magyars, resulting in greater political stability; advancements in medieval technology [like the horse collar and heavy plow ] allowing more land to be farmed; 11th century reforms of the Church that further increased social stability; and the rise of Feudalism, which also brought a measure of social stability.

Towns and trade revived, and the rise of a money economy began to weaken the bonds of serfdom that tied peasants to the land. Land was at first plentiful while labour to clear and work the land was scarce; lords who owned the land found new ways to attract and keep labour. Urban centers were able to attract serfs with the promise of freedom. As new regions were settled, both internally and externally, population naturally increased.

5 Overall, the population of Europe is estimated to have reached a peak of as many as 100 million.

THE HANSEATIC LEAGUE

The Hanseatic League was a commercial and defensive confederation of merchant guilds and their market towns. It dominated Baltic maritime trade (c. 1400–1800) along the coast of Northern Europe. It stretched from the Baltic to the North Sea and inland during the Late Middle Ages and early modern period (c. 15th to 19th centuries). Hanse, later spelled as Hansa, was the Middle Low German word for a convoy, and this word was applied to bands of merchants traveling between the Hanseatic cities whether by land or by sea.

The League was created to protect the guilds' economic interests and diplomatic privileges in their affiliated cities and countries, as well as along the trade routes the merchants visited. The Hanseatic cities had their own legal system and furnished their own armies for mutual protection and aid. Despite this, the organization was not a state, nor can it be called a confederation of city-states; only a very small number of the cities within the league enjoyed autonomy and liberties comparable to those of a free imperial city.

Historians generally trace the origins of the Hanseatic League to the rebuilding of the North German town of Lübeck in 1159 by the powerful Henry the Lion, Duke of Saxony and Bavaria, after Henry had captured the area from Adolf II, Count of Schauenburg and Holstein.

Around AD 700, Slavic peoples started moving into the area around Lubeck, an area previously settled by Germanic inhabitants; the latter had moved on in the course of the Migration Period. Charlemagne (Holy Roman Emperor 800-814), whose efforts to Christianize the area were opposed by the Germanic Saxons, expelled many of the Saxons and brought in Polabian Slavs, allied to Charlemagne, in their stead.

Lübeck became a base for merchants from Saxony and Westphalia trading eastward and northward. Well before the term Hanse appeared in a document in 1267, merchants in different cities began to form guilds, or Hansa, with the intention of trading with towns overseas, especially in the economically less-developed eastern Baltic.

This area was a source of timber, wax, amber, resins, and furs, along with rye and wheat brought down on barges from the hinterland to port markets. The towns raised their own armies, with each guild required to provide levies when needed. The Hanseatic

6 cities came to the aid of one another, and commercial ships often had to be used to carry soldiers and their arms.

Lübeck's location on the Baltic provided access for trade with Scandinavia and Kievan Rus', putting it in direct competition with the Scandinavians who had previously controlled most of the Baltic trade routes. A treaty with the Visby Hansa put an end to this competition: through this treaty the Lübeck merchants also gained access to the inland Russian port of Novgorod, where they built a trading post or Kontor (literally: office).

Other such alliances formed throughout the Holy Roman Empire. Yet the League never became a closely managed formal organization. Assemblies of the Hanseatic towns met irregularly in Lübeck for Hanseatic Diet, from 1356 onwards, but many towns chose not to attend nor to send representatives and decisions were not binding on individual cities. Over the period, a network of alliances grew to include a flexible roster of 70 to 170 cities.

AGE OF DISCOVERY

The Age of Discovery is an informal and loosely defined European historical period from the 15th century to the 18th century, marking the time in which extensive overseas exploration emerged as a powerful factor in European culture and globalization. Many lands previously unknown to Europeans were discovered during this period, though most were already inhabited and from the perspective of many non-Europeans it marked the arrival of settlers and invaders from a previously unknown continent.

Global exploration started with the Portuguese discoveries of the Atlantic archipelagos of Madeira and the Azores, the coast of Africa, and the discovery of the sea route to India in 1498; and, on behalf of the Crown of Castile (Spain), the trans-Atlantic Voyages of Christopher Columbus between 1492 and 1502, and the first circumnavigation of the globe in 1519–1522.

These discoveries led to numerous naval expeditions across the Atlantic, Indian and Pacific oceans, and land expeditions in the Americas, Asia, Africa, and Australia that continued into the late 19th century, and ended with the exploration of the polar regions in the 20th century.

European overseas exploration led to the rise of global trade and the European colonial empires, with the contact between the Old World (Europe, Asia and Africa) and the New World (the Americas and Australia) producing the Columbian Exchange: a wide

7 transfer of plants, animals, food, human populations (including slaves), communicable diseases and culture between the Eastern and Western Hemispheres.

This represented one of the most-significant global events concerning ecology, agriculture, and culture in history. The Age of Discovery and later European exploration allowed the global mapping of the world, resulting in a new world-view and distant civilizations coming into contact.

But it also led to the propagation of diseases that decimated populations not previously in contact with Eurasia and Africa, and to the enslavement, exploitation, military conquest, and economic dominance of Europe and its colonies over native populations. It also allowed for the expansion of Christianity throughout the world, becoming the world's largest religion.

8