Hull
As a boat or ship's hull is the portion of a boat or ship , which gives it the buoyancy. The hull is the finished, buoyant hull without the included technology. In inland shipping , the hull is also known as the ship's shell.
A distinction is made between monohull and multihull ships . The underwater part of the hull is called the underwater hull , its shape (viewed from the side) is called the lateral plan .
conditions
According to Archimedes' principle , the static buoyancy of a body is just as great as the weight of the amount of fluid displaced by the body. When a ship floats on calm water, its total weight is exactly the same as the weight of the amount of water displaced by the ship's hull. In order to be operationally safe while moving, a hull must also have sufficient freeboard and righting capability. In addition, a ship's hull must be built in such a way that it can absorb all forces that occur during operation.
history
At all times the shapes of the ship's hull have been determined by the available building material, the resulting construction, the type of propulsion and the intended use. The hulls of primitive vehicles range from round woven baskets, frames covered with animal skin to long hulls made of reed or hewn tree trunks. The ancient Egyptians tied wooden planks together to make flat-bottomed boat hulls that looked like their papyrus boats. Other peoples in ancient times learned to improve hollowed-out dugouts by spreading them and putting one or more planks on either side. The continued existence of primitive boats / ships in various parts of the world helps identify the regions where the main types of seagoing ships originated, namely the Mediterranean Basin , Northern Europe and China . During the recorded history there was a parallel development of the two basic forms mentioned above, the round ship and the bulbous long ship. The history of shipbuilding largely coincides with the history of vehicles and sailing ships moved by means of wooden belts.
Building systems
Two basic building systems were used in the construction of wooden ships: the shell and the skeleton or frame construction. Combinations of both have been demonstrable since the 7th century AD. In the case of the wreck of Yassiada (approx. 625/626 AD), for example, the shell construction was used up to the waterline, while the ship's side above the waterline was built using a frame construction.
In the case of the shell construction, the planks were attached to one another using tenons and dowels and then the frames were inserted. With the skeleton construction, however, the planks had to follow the set up skeleton system. Until recently, the Serçe Limanı wreck off the Turkish coast, dated to the 11th century, was considered to be the oldest ship built using pure frame construction. However, first evaluations of the archaeological findings of the excavation campaign carried out in the course of the Marmaray project in Istanbul from 2004 to 2009 show that as early as the 8th century AD, ships were built in pure skeleton or frame construction (the wrecks bear the project name "YK 15" and "YK 17").
The appearance of the early timbered ships was largely shaped by the building materials and tools used. Ancient Scandinavian shipbuilders used ax and adze to cut a long plank from the two halves of a split log. The planks obtained in this way were interconnected, overlapping, with willow rods or animal tendons (later metal rivets). That was the beginning of the later clinker paneling. When a sufficient number of planks had been attached to each other and to the stems at the front and rear, supporting frames were inserted, which were lashed to the straps left when the planks were being worked on.
Egypt
Shipbuilders in ancient Egypt used the saw to cut several planks out of a trunk. The common native woods ( acacia and sycamore wood ) were only available in short lengths, which led Herodotus to compare the construction of an Egyptian ship with a brick wall. Old finds show how the planks were fastened edge to edge using various combinations of dowels and tenons, recessed dovetail-shaped connecting pieces and lashings, creating the smooth outer skin that we now call Kraweel planking. Since the Egyptian ships were initially only river ships, they often only had a thick keel plank instead of a built beam keel. A striking feature of many Egyptian ships was a very strong longitudinal bracing made of cordage that ran over a support post from bow to stern, which prevented the ends of the ship from hanging down.
Mediterranean area
The Phoenician , Greek and Roman ships were basically Spitzgatt ships . Their shipbuilders, who used the shell construction method, had a very solid knowledge of the construction methods required for seagoing ships. Reports of numerous Roman warships built within a short period of time - in 254 there were 220 ships built within three months - suggest that they used something like frame templates to be able to build series of the same ships . The Romans had three basic types of ships: rounded sailing merchant ships, stout, oar-belt-driven warships used for ramming in naval battles, and light, fast galleys for carrying messages and important people. From the time of the Romans to around the 12th century, the shapes of the ships in the Mediterranean area changed little. The sailing merchant ships remained double-ended with a complete stern and were steered with a heavy, laterally mounted oar. An important change was the change from the old Roman rigging to a two- or three-masted Latin rigging for the majority of merchant ships. Since the time of the first crusades around 1095, when northern European ships invaded the Mediterranean in large numbers, the characteristics of the circular ships of the north and the south gradually mixed.
Northern European area
In Northern Europe, the typical Viking ship had meanwhile been replaced by Spitzgattsegelschiffen, in which the clinker construction, high fore and aft stems and the side rudder were still retained. These ships became wider and deeper in proportion to their length. Small forts appeared on the bow and stern, which over time became more and more pronounced. Stern rudders were first used in the second half of the 12th century. The shipbuilders of the south also adopted the stern rudder, and on their larger ships they returned to the rigging . Around this time, the first cogs appeared, which up into the 15th century, the Mediterranean to the Baltic Sea, were the standard type.
China
The origins of the Chinese ships are lost in the dark of history. Some types of boats in the Upper Yangtze are almost identical to Egyptian ships from around 1600 BC. A Chinese report from the year 1119 compares the shape of the hull of the ships with a right-angled grain size that has sloping sides and end faces. Furthermore, a mat sail is described that moved around the mast like a door in a hinge. Far ahead of western technology, the Chinese were already building ships ( junks ) with several watertight transverse bulkheads; it is believed that they were inspired by the bamboo . They also had balancing rudders since the first and leeboards since the eighth century.
Middle Ages to the 19th century
During the 15th century, ships in Europe kept getting bigger, until it became apparent to the shipbuilders of the north that there were limits to the dimensions of clinker ships. The larger ships of Europe combined the characteristics of the north and the south. Since the outer skin was difficult to seal at the points of the protruding beam heads, this construction method was abandoned. Smooth planking was placed on a previously erected frame structure, the decks only supported on the inside. It is difficult to precisely describe some of the types of ships that follow the cog, such as the galleon , galeas and galiot, as well as the total cargo ships holk , carrack and caravel .
During the 15th and 16th centuries, the appearance of European ships changed considerably. The forts remained large, but lost their angularity and merged with the lines of the hull. In the second half of the 16th century, the large ships began to be given a transom stern, which offered the superstructure better support than the medieval round stern. At the same time, the front fort lost its triangular shape and formed a ship's beak under the bowsprit, imitating the Rammstevens of the galley. The galleon became the primary type of ship for the next 100 years. It had less crack , lower superstructure and was narrower in relation to the length than the earlier types.
The 17th century brought a significant improvement in frame construction. Until the late 16th century, the single frame lashed together from several crooked pieces of wood was the norm for ships of almost all sizes. However, the connection points were weak points, which is why the pieces of wood were now placed next to each other at the connection points, offset from each other so that they each overlapped by a few feet. The frame spacing on the keel was equal to the frame thickness, so that the frames on the doublings stood close together over the entire length of the ship. They were not attached to each other, but were held in place by planking and interior flooring.
The semicircular cross-section of the dugout was not very favorable in terms of a stable floating position, but the boat builders soon noticed that this could be improved by flattening the bottom. In general, the underwater shape of the main frame of almost all ships up to the 18th century can be described as an approximate semicircle. The V-frame shape of the Viking ships was unusual and remained a Scandinavian peculiarity. Changes in the underwater shape did not take place until the 18th and 19th centuries.
present
Notable changes in the shape of the hull were the " Wellenbinder " developed by the boat builder and engineer Claus Engelbrecht in 1910 and later improved by the shipbuilding engineer Arthur Tiller , as well as the "DG-Hull" (Deplacement-Glider-Hull) developed by the Austrian physicist Theodor Eder = Displacement glider fuselage). At the end of the 1890s, Eder had received an order from the mayor of Venice to develop a hull that would not throw a wave. See also: displacer and glider
Shipbuilding plans
The oldest surviving ship plans and treatises on shipbuilding date from the early 15th century. They are written in Italian and describe the construction technology of the Mediterranean area. Until 1750, and perhaps even later, it was possible to design a ship with just a compass and ruler . English reports on the results of what were probably the first systematic attempts to determine the ship's resistance come from around 1670. Further scientific studies followed, especially in France , where the first treatise on stability was published by Pierre Bouguer in 1746 .
In the 18th century, both legal and illegal activities demanded small speed sailors. The ships built first in Jamaica , later in Bermuda and on the coasts of Chesapeake Bay became world famous. The terms "Virginia-built" or "Virginia-model" were synonyms for speed . In the early 19th century, this type was known as the Baltimore clipper . A noticeable feature at that time was a return to the V-shaped ship's bottom of the Viking ship , the ships were given a strong " dead-up " whenever speed was more important than carrying capacity.
Baltimore clippers were used in the India and China trade , but their speed could not compensate for their limited loading capacity, which was a result of the V-bottom shape. The best ships in the China trade represented a compromise and had fuller lines. The era of the clipper, which began in the 1840s, ended in the USA in 1857 and in England around 1870. The great clippers grew out of an increasing urge for high speed, fueled primarily by the gold discoveries in California and Australia . The load capacity came second. The record speeds of the clippers were mainly achieved by very hard sailing, which the long, fast hulls of the ship made a real challenge. But in the end economic pressure forced a return to economic forms of ship; H. to ships that weren't quite as fast, but could transport more cargo.
The decorating of the ships with figurative carvings such as animals , gods and goddesses can be traced back to antiquity , whereby the depiction of the latter was more likely to aim to secure divine protection than to decorate the ship. The Vikings provided the stems of their ships with wild dragon heads (dragon ships) to frighten their enemies. Around 1600 began a period of more than a century of the most elaborate ship decorations. Both war and merchant ships were decorated with rich carvings; There were large figureheads at the stern , aft galleries, sides, and front . From 1800 onwards one limited oneself to a few rear windows with a little ornamental carving on the mirror, small rear galleries and a few simple front decorations.
The introduction of the steam drive in the early 19th century presented the shipbuilders with new problems, namely the high weight of the machine and the high stresses caused by the paddle wheels and the propellers . Until their last phase, the wheel arches of the paddle steamers built in Europe were only attached to the hull as attachments. Until 1870 sea-going steamers had the shape customary for sailing ships , and the steamers were also built like the sailors. The steam drive was still unreliable, so the ships also had a reduced rigging for sailing ships. Emergency sails for steamers existed until the First World War . Since the middle of the 19th century, further attempts to measure ship resistance and practical experience with steam propulsion had shown that sharp lines were a prerequisite for high speeds. On a sailing ship, unfavorable ship lines could be compensated somewhat by more sail area, but the still young engine drive was limited in its performance and breakdowns occurred frequently. The consequences were sometimes catastrophic (e.g. boiler explosion ).
See also
Web links
- Why do ships swim? In: swr.de.
Individual evidence
- ↑ Frederick Van Doorninck: The ship of Georgios, priest and captain. Yassiada, Turkey. In: George F. Bass (ed.): The depth. Herbig, Munich 2006. ISBN 3-7766-2483-3
- ↑ ISTL and Ufuk Kocabaş: Technological and Constructional features of Yenikapi Shipwrecks. A preliminary evaluation. In: Ufuk Kocabaş (Ed.): The 'Old Ships' of the 'New Gate'. Yenikapi Shipwrecks. Vol. 1. Istanbul 2008. ISBN 9758072161