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Circular Arc Hull
The circular arc hull is a design for boat hulls created by Swedish engineer Fredrik Ljungström. In the 1930s and 1940s Ljungström designed and built sailboats, commonly called the Ljungström sailboat. Ribs The frames, or ribs, of a circular arc hull all have the same radius. On Fredrik Ljungström's first models, frames were a cross-section (a single arc), but he soon realized that he needed a slightly narrower profile to cope with the sea. The result was that two arcs met at the bottom so that a slightly pointed bottom was created. The frames are tilted toward the mast so that the stern and bow lean while standing straight up. Keel stock Ljungström's yachts lack a traditional keel stock. The lower plank is twice as wide. Its curvature is a circular arc with its radius approximately equal to the length of the mast. Planking The table planks consist entirely of parallel ribs that begin and end at the rail. The bottom (longest) plank runs from stem to stern and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hull (watercraft)
A hull is the watertight body of a ship, boat, or flying boat. The hull may open at the top (such as a dinghy), or it may be fully or partially covered with a deck. Atop the deck may be a deckhouse and other superstructures, such as a funnel, derrick, or mast. The line where the hull meets the water surface is called the waterline. General features There is a wide variety of hull types that are chosen for suitability for different usages, the hull shape being dependent upon the needs of the design. Shapes range from a nearly perfect box in the case of scow barges to a needle-sharp surface of revolution in the case of a racing multihull sailboat. The shape is chosen to strike a balance between cost, hydrostatic considerations (accommodation, load carrying, and stability), hydrodynamics (speed, power requirements, and motion and behavior in a seaway) and special considerations for the ship's role, such as the rounded bow of an icebreaker or the flat bottom of a landing craft. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fredrik Ljungström
Fredrik Ljungström (16 June 1875 – 18 February 1964) was a Swedish engineer, technical designer, and industrialist. Considered one of the foremost inventors of Sweden, Fredrik Ljungström accounted for hundreds of technical patents alone and in collaboration with his brother Birger Ljungström (1872–1948): from early bicycling free wheeling hubs techniques and mechanical automatic transmissions for vehicles, to steam turbines, air preheaters, and circular arc hulls for sailing boats. He co-founded companies such as The New Cycle Company, Ljungström Steam Turbine Co. and Ljungström Swedish Turbine Manufacturing Co. (STAL), and associated with other industrialists such as Alfred Nobel, Helge Palmcrantz, Gustaf de Laval, Curt Nicolin, and Gustaf Dalén. As innovative as his ideas were in function, they also often turned out in terms of unconventional external design, such as his steam turbine locomotives and sailboats. During the resource scarcity of World War II, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ljungström Sailboat
Ljungström sailboats were created by the Swedish engineer Fredrik Ljungström, who was interested in sailing since childhood. A "Ljungström sailboat" typically has a "circular arc" hull and a "Ljungström rig". A Ljungström rig mast has no mast stays. The mast rotates on two ball bearings often flying double mainsails, with no foresails. In their time the Ljungström sailboats were a minor revolution as they were fast, safe and easy to sail as well as relatively easy and affordable to produce. The models were named The Wing and the number (Swedish Vingen 1, Vingen 2 etc.) chronologically. A few models were built in series, such as Vingen 11A and the Twin Wing which was specifically produced for the US market. The design was not appreciated by the fairly conservative yacht clubs at the time, so development was done with scarce means. Approximately sixty boats (of different sizes) were produced. Approximately eighteen are known to still exist; a dozen of those are sailing, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frame (nautical)
In ships, frames are ribs that are transverse bolted or welded to 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 .... Frames support the hull and give the ship its shape and strength. In wooden shipbuilding, each frame is composed of several sections, so that the grain of the wood can follow the curve of the frame. Starting from the keel, these are the floor (which crosses the keel and joins the frame to the keel), the first futtock, the second futtock, the top timber, and the rail stanchion. In steel shipbuilding, the entire frame can be formed in one piece by rivetting or welding sections; in this case the floor remains a separate piece, joining the frame on each side to the keel. Frame numbers are the numerical values given to the frames; they begin at 1 with the for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radius
In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the spoke of a chariot wheel. as a function of axial position ../nowiki>" Spherical coordinates In a spherical coordinate system, the radius describes the distance of a point from a fixed origin. Its position if further defined by the polar angle measured between the radial direction and a fixed zenith direction, and the azimuth angle, the angle between the orthogonal projection of the radial direction on a reference plane that passes through the origin and is orthogonal to the zenith, and a fixed reference direction in that plane. See also *Bend radius *Filling radius in Riemannian geometry *Radius of convergence * Radius of convexity *Radius of curvature *Radius of gyration ''Radius of gyration'' or gyradius of a body about the axis of r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mast (sailing)
The mast of a sailing vessel is a tall spar, or arrangement of spars, erected more or less vertically on the centre-line of a ship or boat. Its purposes include carrying sails, spars, and derricks, and giving necessary height to a navigation light, look-out position, signal yard, control position, radio aerial or signal lamp. Large ships have several masts, with the size and configuration depending on the style of ship. Nearly all sailing masts are guyed. Until the mid-19th century, all vessels' masts were made of wood formed from a single or several pieces of timber which typically consisted of the trunk of a conifer tree. From the 16th century, vessels were often built of a size requiring masts taller and thicker than could be made from single tree trunks. On these larger vessels, to achieve the required height, the masts were built from up to four sections (also called masts). From lowest to highest, these were called: lower, top, topgallant, and royal masts. Giving the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 British and American shipbuilding traditions the construction is dated from this event. Etymology The word "keel" comes from Old English , Old Norse , = "ship" or "keel". It has the distinction of being regarded by some scholars as the first word in the English language recorded in writing, having been recorded by Gildas in his 6th century Latin work ''De Excidio et Conquestu Britanniae'', under the spelling ''cyulae'' (he was referring to the three ships that the Saxons first arrived in). is the Latin word for "keel" and is the origin of the term careen (to clean a keel and the hull in general, often by rolling the ship on its side). An example of this use is Careening Cove, a suburb of Sydney, Australia, where careening was carried out ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluid Mechanics
Fluid mechanics is the branch of physics concerned with the mechanics of fluids ( liquids, gases, and plasmas) and the forces on them. It has applications in a wide range of disciplines, including mechanical, aerospace, civil, chemical and biomedical engineering, geophysics, oceanography, meteorology, astrophysics, and biology. It can be divided into fluid statics, the study of fluids at rest; and fluid dynamics, the study of the effect of forces on fluid motion. It is a branch of continuum mechanics, a subject which models matter without using the information that it is made out of atoms; that is, it models matter from a ''macroscopic'' viewpoint rather than from ''microscopic''. Fluid mechanics, especially fluid dynamics, is an active field of research, typically mathematically complex. Many problems are partly or wholly unsolved and are best addressed by numerical methods, typically using computers. A modern discipline, called computational fluid dynamics (CFD), is dev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Popular Science
''Popular Science'' (also known as ''PopSci'') is an American digital magazine carrying popular science content, which refers to articles for the general reader on science and technology subjects. ''Popular Science'' has won over 58 awards, including the American Society of Magazine Editors awards for its journalistic excellence in 2003 (for General Excellence), 2004 (for Best Magazine Section), and 2019 (for Single-Topic Issue). With roots beginning in 1872, ''Popular Science'' has been translated into over 30 languages and is distributed to at least 45 countries. Early history ''The Popular Science Monthly'', as the publication was originally called, was founded in May 1872 by Edward L. Youmans to disseminate scientific knowledge to the educated layman. Youmans had previously worked as an editor for the weekly ''Appleton's Journal'' and persuaded them to publish his new journal. Early issues were mostly reprints of English periodicals. The journal became an outlet for writings ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wood
Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin that resists compression. Wood is sometimes defined as only the secondary xylem in the stems of trees, or it is defined more broadly to include the same type of tissue elsewhere such as in the roots of trees or shrubs. In a living tree it performs a support function, enabling woody plants to grow large or to stand up by themselves. It also conveys water and nutrients between the leaves, other growing tissues, and the roots. Wood may also refer to other plant materials with comparable properties, and to material engineered from wood, or woodchips or fiber. Wood has been used for thousands of years for fuel, as a construction material, for making tools and weapons, furniture and paper. More recently it emerged as a feedstock for the productio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Keelboats
A keelboat is a riverine cargo-capable working boat, or a small- to mid-sized recreational sailing yacht. The boats in the first category have shallow structural keels, and are nearly flat-bottomed and often used leeboards if forced in open water, while modern recreational keelboats have prominent fixed fin keels, and considerable draft. The two terms may draw from cognate words with different final meaning. A keep boat, keelboat, or keel-boat is a type of usually long, narrow cigar-shaped riverboat, or unsheltered water barge which is sometimes also called a poleboat—that is built about a slight keel and is designed as a boat built for the navigation of rivers, shallow lakes, and sometimes canals that were commonly used in America including use in great numbers by settlers making their way west in the century-plus of wide-open western American frontiers. They were also used extensively for transporting cargo to market, and for exploration and trading expeditions, for wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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