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Inclined Rig
A Bruce foil is a variant of the leeboard, consisting of a foil typically mounted on an outrigger and always set at an angle to provide both lateral and vertical force. It was invented by Edmond Bruce in the early 1960s, and first published in the Amateur Yacht Research Society publication in April 1965. Theory Nearly all methods that increase resistance to sideways movement also cause heeling, the leaning produced by the imbalance of the forces on the sails, high above the waterline, and the sideways resistance, generated by the centerboard or other foil below the waterline. The resulting torque causes the hull to heel until the buoyancy of the hull provides sufficient torque to balance the heeling force. The limited buoyancy of the hull therefore limits the amount of force that the sail can effectively produce. One solution to dealing with this limit is to bring the forces generated by the sail and the underwater foil into alignment, canceling as much of the torque as possible ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leeboard
A leeboard is a form of pivoting keel used largely by sailboats, very often in lieu of a fixed keel. Typically mounted in pairs on each side of a hull, leeboards function much like a centreboard, allowing shallow-draft craft to ply waters inaccessible to fixed-keel boats. Only the leeward side leeboard is used at any time, as it submerges when the boat heels under the force of the wind. A disadvantage, where there is an inadequate fixed keel, is that leeboards typically ship (bear) little ballast, and being on the far ( lee) side delays the onset of unballasted craft's heeling, that is, inhibits the effect of putting up a good, constant resistance against the wind. The classical, archetypal definition of ballast is a low, central weight to optimise centre of mass, to reduce turning moment and therefore resistance to the boat keeling over; however, the centre of gravity tends to be higher in self-righting vessels. Modern developments allow leeboards to act as a speed-enh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inclined Rig
A Bruce foil is a variant of the leeboard, consisting of a foil typically mounted on an outrigger and always set at an angle to provide both lateral and vertical force. It was invented by Edmond Bruce in the early 1960s, and first published in the Amateur Yacht Research Society publication in April 1965. Theory Nearly all methods that increase resistance to sideways movement also cause heeling, the leaning produced by the imbalance of the forces on the sails, high above the waterline, and the sideways resistance, generated by the centerboard or other foil below the waterline. The resulting torque causes the hull to heel until the buoyancy of the hull provides sufficient torque to balance the heeling force. The limited buoyancy of the hull therefore limits the amount of force that the sail can effectively produce. One solution to dealing with this limit is to bring the forces generated by the sail and the underwater foil into alignment, canceling as much of the torque as possible ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ama (sailing)
Polynesian multihull terminology, such as "ama", "aka" and "vaka" (or "waka") are multihull terms that have been widely adopted beyond the South Pacific where these terms originated. This Polynesian terminology is in common use in the Americas and the Pacific but is almost unknown in Europe, where the English terms "hull" and "outrigger" form normal parlance. Outriggers, catamarans, and outrigger boats are a common heritage of all Austronesian peoples and predate the Micronesian and Polynesian expansion into the Pacific. They are also the dominant forms of traditional ships in Island Southeast Asian and Malagasy Austronesian cultures, where local terms are used. Etymology The term ''vaka'' or ''waka'' means "boat" or "canoe" in most Polynesian languages. It comes from Proto-Austronesian *abaŋ, meaning "ship" or "canoe". Cognates in other Austronesian languages include Ivatan ''Awang'', Tagalog and Visayan ''bangka'', Malay ''wangkang'', and Fijian ''waqa''. "Ama", "ak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trimaran
A trimaran (or double-outrigger) is a multihull boat that comprises a main hull and two smaller outrigger hulls (or "floats") which are attached to the main hull with lateral beams. Most modern trimarans are sailing yachts designed for recreation or racing; others are ferries or warships. They originated from the traditional double-outrigger hulls of the Austronesian cultures of Maritime Southeast Asia; particularly in the Philippines and Eastern Indonesia, where it remains the dominant hull design of traditional fishing boats. Double-outriggers are derived from the older catamaran and single-outrigger boat designs. Terminology The word "trimaran" is a portmanteau of "tri" and "(cata)maran", a term that is thought to have been coined by Victor Tchetchet, a pioneering, Ukrainian-born modern multihull designer. Trimarans consist of a main hull connected to outrigger floats on either side by a crossbeam, wing, or other form of superstructure—the traditional Polynesian te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Windward
In geography and seamanship, windward () and leeward () are directions relative to the wind. Windward is ''upwind'' from the point of reference, i.e., towards the direction from which the wind is coming; leeward is ''downwind'' from the point of reference, i.e., along the direction towards which the wind is going. The side of a ship that is towards the leeward is its "lee side". If the vessel is heeling under the pressure of crosswind, the lee side will be the "lower side". During the Age of Sail, the term ''weather'' was used as a synonym for ''windward'' in some contexts, as in the '' weather gage''. Since it captures rainfall, the windward side of a mountain tends to be wetter than the leeward side it blocks. The drier leeward area is said to be in a rain shadow. Origin The term "windward" has roots in both Low German and Old English. The word "lee", which means a place without wind, comes from the Old Norse "hle" for "cover" and has been used in marine navigation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angle Of Attack
In fluid dynamics, angle of attack (AOA, α, or \alpha) is the angle between a Airfoil#Airfoil terminology, reference line on a body (often the chord (aircraft), chord line of an airfoil) and the vector (geometry), vector representing the relative motion between the body and the fluid through which it is moving. Angle of attack is the angle between the body's reference line and the oncoming flow. This article focuses on the most common application, the angle of attack of a wing or airfoil moving through air. In aerodynamics, angle of attack specifies the angle between the chord line of the wing of a fixed-wing aircraft and the vector representing the relative motion between the aircraft and the atmosphere. Since a wing can have twist, a chord line of the whole wing may not be definable, so an alternate reference line is simply defined. Often, the chord line of the Wing root, root of the wing is chosen as the reference line. Another choice is to use a horizontal line on the fuse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leeward
In geography and seamanship, windward () and leeward () are directions relative to the wind. Windward is ''upwind'' from the point of reference, i.e., towards the direction from which the wind is coming; leeward is ''downwind'' from the point of reference, i.e., along the direction towards which the wind is going. The side of a ship that is towards the leeward is its "lee side". If the vessel is heeling under the pressure of crosswind, the lee side will be the "lower side". During the Age of Sail, the term ''weather'' was used as a synonym for ''windward'' in some contexts, as in the '' weather gage''. Since it captures rainfall, the windward side of a mountain tends to be wetter than the leeward side it blocks. The drier leeward area is said to be in a rain shadow. Origin The term "windward" has roots in both Low German and Old English. The word "lee", which means a place without wind, comes from the Old Norse "hle" for "cover" and has been used in marine navigation in G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NACA
The National Advisory Committee for Aeronautics (NACA) was a United States federal agency that was founded on March 3, 1915, to undertake, promote, and institutionalize aeronautical research. On October 1, 1958, the agency was dissolved and its assets and personnel were transferred to the newly created National Aeronautics and Space Administration (NASA). NACA is an initialism, pronounced as individual letters rather than as a whole word, as was NASA during the early years after being established. Among other advancements, NACA research and development produced the NACA duct, a type of air intake used in modern automotive applications, the NACA cowling, and several series of NACA airfoils, which are still used in aircraft manufacturing. During World War II, NACA was described as "The Force Behind Our Air Supremacy" due to its key role in producing working superchargers for high altitude bombers, and for producing the laminar wing profiles for the North American P-51 Mustan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torque
In physics and mechanics, torque is the rotational analogue of linear force. It is also referred to as the moment of force (also abbreviated to moment). The symbol for torque is typically \boldsymbol\tau, the lowercase Greek letter ''tau''. When being referred to as moment of force, it is commonly denoted by . Just as a linear force is a push or a pull applied to a body, a torque can be thought of as a twist applied to an object with respect to a chosen point; for example, driving a screw uses torque to force it into an object, which is applied by the screwdriver rotating around its axis to the drives on the head. Historical terminology The term ''torque'' (from Latin , 'to twist') is said to have been suggested by James Thomson and appeared in print in April, 1884. Usage is attested the same year by Silvanus P. Thompson in the first edition of ''Dynamo-Electric Machinery''. Thompson describes his usage of the term as follows: Today, torque is referred to using d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrofoil
A hydrofoil is a lifting surface, or foil, that operates in water. They are similar in appearance and purpose to aerofoils used by aeroplanes. Boats that use hydrofoil technology are also simply termed hydrofoils. As a hydrofoil craft gains speed, the hydrofoils lift the boat's hull out of the water, decreasing drag and allowing greater speeds. Description The hydrofoil was created by Eric Walters. The hydrofoil usually consists of a winglike structure mounted on struts below the hull, or across the keels of a catamaran in a variety of boats (see illustration). As a hydrofoil-equipped watercraft increases in speed, the hydrofoil elements below the hull(s) develop enough lift to raise the hull out of the water, which greatly reduces hull drag. This provides a corresponding increase in speed and fuel efficiency. Wider adoption of hydrofoils is prevented by the increased complexity of building and maintaining them. Hydrofoils are generally prohibitively more expensive than ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foil (fluid Mechanics)
A foil is a solid object with a shape such that when placed in a moving fluid at a suitable angle of attack the lift (force generated perpendicular to the fluid flow) is substantially larger than the drag (force generated parallel to the fluid flow). If the fluid is a gas, the foil is called an airfoil or aerofoil, and if the fluid is water the foil is called a hydrofoil. Physics of foils A foil generates lift primarily because of its shape and angle of attack. When oriented at a suitable angle, the foil deflects the oncoming fluid, resulting in a force on the foil in the direction opposite to the deflection. This force can be resolved into two components: lift and drag. This "turning" of the fluid in the vicinity of the foil creates curved streamlines which results in lower pressure on one side and higher pressure on the other. This pressure difference is accompanied by a velocity difference, via Bernoulli's principle, so for foils generating lift the resulting flowfield ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centerboard
A centreboard or centerboard (US) is a retractable hull appendage which pivots out of a slot in the hull of a sailboat, known as a ''centreboard trunk'' (UK) or ''centerboard case'' (US). The retractability allows the centreboard to be raised to operate in shallow waters, to move the centre of lateral resistance (offsetting changes to the sailplan that move the centre of effort aft), to reduce drag when the full area of the centreboard is not needed, or when removing the boat from the water, as when trailering. A centreboard which consists of solely a pivoting metal plate is called a centerplate; the term "centreboard" may refer to either a wooden or a metal pivoting retractable foil. A daggerboard is similar but slides vertically rather than pivoting. The analog in a scow is a bilgeboard: these are fitted in pairs and used one at a time. General History Lt. John Schank (c. 1740 – 6 February 1823) was an officer of the British Royal Navy and is credited with the invention ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
