Information about Centreboard
A centreboard is a retractable keel which pivots out of a slot in the hull of a sailboat, known as a centerboard trunk (US) or case. The pivoting ability allows the centreboard to be raised to operate in shallow waters, to reduce drag when the full area of the centreboard isn't needed, or to remove the boat from the water as on a trailer. A daggerboard is similar but slides vertically rather than pivoting.
Centreboards are often ballasted. Ballasted centreboards are generally not locked in place when lowered; the mass of the ballast keeps them down. This also provides a measure of safety should the boat run aground—the force of impact will push the foil back into the centreboard trunk, rather than breaking it as might happen if the board were locked in place. The mass of a ballasted foil means that a system of pulleys may be required to allow the sailor to lift the foil, and a method of latching the board in the upward position is needed. A centerboard differs from a ballast keel in that centerboards do not contribute to the stability of the vessel; their purpose is to provide lateral resistance.
Function
A centreboard is used to provide lift to counter the lateral force from the sails. This is required for sailboats to move in directions other than downwind, since the force of the sail is never closer than 90 degrees to the apparent wind. Since most sailboats are symmetric along their axis of motion, the lateral force can come from either side, which means that centreboards must use symmetric foil shapes so they will operate with equal efficiency on either tack.Design
The efficiency of a centreboard improves with increasing aspect ratio. A long narrow centreboard produces less drag than a short, wide one for a given amount of lift, resulting in a faster boat that can point closer into the wind. A pivoting centreboard can also be used to move the center of lateral resistance aft to match a change in sail plan such as furling or dropping the jib. A retracting centreboard is more complex than a fixed keel, and most take up space inside the hull of the boat that could otherwise be used for passenger accommodations. For this reason, it is not uncommon to find boats with combination of shallow keel and centreboard. The keel provides the housing for the centreboard, moving it out of the hull, but only adds a small amount of draft to the boat. The centreboard can then be lowered in deeper waters to increase the amount of lift. Ballast is usually provided in the keel, keeping the centreboard lighter and easier to handle.Centreboards are often ballasted. Ballasted centreboards are generally not locked in place when lowered; the mass of the ballast keeps them down. This also provides a measure of safety should the boat run aground—the force of impact will push the foil back into the centreboard trunk, rather than breaking it as might happen if the board were locked in place. The mass of a ballasted foil means that a system of pulleys may be required to allow the sailor to lift the foil, and a method of latching the board in the upward position is needed. A centerboard differs from a ballast keel in that centerboards do not contribute to the stability of the vessel; their purpose is to provide lateral resistance.
See also
KEEL 710AM is a general talk radio station in Shreveport, Louisiana. It is owned by Gap Broadcasting.
The station's lineup includes Rush Limbaugh, Sean Hannity, Michael Savage, and a local sports talk show hosted by the team of "J.J. and Bonzai Ben.
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The station's lineup includes Rush Limbaugh, Sean Hannity, Michael Savage, and a local sports talk show hosted by the team of "J.J. and Bonzai Ben.
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sailboat or sailing-boat is a boat propelled partly or entirely by sails. The term covers a variety of boats, larger than small vessels such as sailboards and smaller than sailing ships, but distinctions in size are not strictly defined and what constitutes a sailing ship,
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A Trailer is generally an unpowered vehicle pulled by a powered vehicle. Commonly, the term trailer refers to such vehicles used for transport of goods and materials.
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A daggerboard is a retractable keel used by various sailing craft. While other types of centreboard may pivot to retract, a daggerboard slides in a casing. The shape of the daggerboard converts the forward motion into a windward lift, countering the leeward push of the sail.
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The lift force, lifting force or simply lift is a mechanical force generated by solid objects as they move through a fluid.[1]
While many types of objects can generate lift, the most common and familiar object in this category is the airfoil, a
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While many types of objects can generate lift, the most common and familiar object in this category is the airfoil, a
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sail is any type of surface intended to generate thrust by being placed in a wind — in essence a vertically-oriented wing. Sails are used in sailing.
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Use of sails
Sails are primarily used at sea, on sailing ships as a propulsion system...... Click the link for more information.
sail is any type of surface intended to generate thrust by being placed in a wind — in essence a vertically-oriented wing. Sails are used in sailing.
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Use of sails
Sails are primarily used at sea, on sailing ships as a propulsion system...... Click the link for more information.
aspect ratio is an airplane's wing's span divided by its standard mean chord (SMC). It can be calculated more easily as span squared divided by wing area:
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KEEL 710AM is a general talk radio station in Shreveport, Louisiana. It is owned by Gap Broadcasting.
The station's lineup includes Rush Limbaugh, Sean Hannity, Michael Savage, and a local sports talk show hosted by the team of "J.J. and Bonzai Ben.
..... Click the link for more information.
The station's lineup includes Rush Limbaugh, Sean Hannity, Michael Savage, and a local sports talk show hosted by the team of "J.J. and Bonzai Ben.
..... Click the link for more information.
A leeboard is a lifting foil used by a sailboat, much like a centerboard, but located on the leeward side of the boat. The leeward side is used so that the leeboard isn't lifted from the water when the boat heels, or leans under the force of the wind.
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A bilgeboard is a lifting foil used in a sailboat, which resembles a cross between a centerboard and a leeboard. Bilgeboards are mounted between the centerline of the boat and the sides, and are almost always asymmetric foils mounted at an angle to maximize lateral lift while
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A daggerboard is a retractable keel used by various sailing craft. While other types of centreboard may pivot to retract, a daggerboard slides in a casing. The shape of the daggerboard converts the forward motion into a windward lift, countering the leeward push of the sail.
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Sailing ship is now used to refer to any large, wind-powered, vessel. In technical terms, a ship was a sailing vessel with a specific rig of at least three masts, square rigged on all of them, making the sailing adjective redundant.
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anchor is a heavy object, often made out of metal, that is used to attach a ship to the bottom of a body of water at a specific point. There are two primary classes of anchors—temporary and permanent.
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anchor windlass is a machine that restrains and manipulates the anchor chain and/or rope on a boat, allowing the anchor to be raised and lowered. A notched wheel engages the links of the chain or the rope.
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beakhead is the protruding part of the foremost section of a sailing ship. It was fitted on sailing vessels from the 16th to the 18th century and served as a working platform by sailors working the sails of the bowsprit, the forward-pointing mast that carries the spritsails.
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A bilgeboard is a lifting foil used in a sailboat, which resembles a cross between a centerboard and a leeboard. Bilgeboards are mounted between the centerline of the boat and the sides, and are almost always asymmetric foils mounted at an angle to maximize lateral lift while
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boom brake is a device designed to control the swing of the boom on a sailboat. The boom brake acts as a preventer when sailing downwind, and can also be used to jibe the mainsail in a slow measured action.
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bow (pronounced to rhyme with how) is a nautical term that refers to the forward part of the hull of a ship or boat, the point that is most forward when the vessel is underway. Both of the adjectives fore and forward mean towards the bow.
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capstan is a rotating machine used to apply force to another element, notably used on board ship and on dock walls, for heaving-in or veering ropes, cables, and hawsers.
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A daggerboard is a retractable keel used by various sailing craft. While other types of centreboard may pivot to retract, a daggerboard slides in a casing. The shape of the daggerboard converts the forward motion into a windward lift, countering the leeward push of the sail.
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A deck is a permanent covering over a compartment or a hull[1] of a ship. On a boat or ship, the primary deck is the horizontal structure which forms the 'roof' for the hull, which both strengthens the hull and serves as the primary working surface.
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figurehead is a carved wooden decoration, often female or bestial, found at the prow of ships of the 16th to the 19th century. The practice was introduced with the galleons of the 16th century, as although earlier ships had often had some form of bow ornamentation, the figurehead
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Forecastle", also spelled fo'c's'le (pronounced /'fəʊksəl/), originally meant the upper deck of a sailing ship, forward of the foremast.
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The gunwale, (IPA /gʌnəl/ ) pronounced "gunnel" to rhyme with "tunnel", is a nautical term describing the top edge of the side of a boat.
Wale is the same word as the skin injury, a weal, which, too, forms a ridge.
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Wale is the same word as the skin injury, a weal, which, too, forms a ridge.
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A hull is the body of a ship or boat. It is a central concept in floating vessels as it provides the buoyancy that keeps the vessel from sinking.
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General features
Nearly all watercraft, from small boats to the largest ships, adhere to a general form that serve the needs of..... Click the link for more information.
jackline is a rope or wire strung from a ship's bow to stern to which a safety harness can be clipped, allowing a crewmember to move about the deck safely when there is risk of falling or being swept overboard.
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KEEL 710AM is a general talk radio station in Shreveport, Louisiana. It is owned by Gap Broadcasting.
The station's lineup includes Rush Limbaugh, Sean Hannity, Michael Savage, and a local sports talk show hosted by the team of "J.J. and Bonzai Ben.
..... Click the link for more information.
The station's lineup includes Rush Limbaugh, Sean Hannity, Michael Savage, and a local sports talk show hosted by the team of "J.J. and Bonzai Ben.
..... Click the link for more information.
A canting keel is a form of sailing ballast, suspended from a rigid canting strut beneath the boat, which can be swung to windward of a boat under sail, in order to counteract the heeling force of the sail.
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A leeboard is a lifting foil used by a sailboat, much like a centerboard, but located on the leeward side of the boat. The leeward side is used so that the leeboard isn't lifted from the water when the boat heels, or leans under the force of the wind.
..... Click the link for more information.
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