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Autohelm
Self-steering gear is equipment used on sail boats to maintain a chosen course or point of sail without constant human action. History Mechanical or "wind vane" self-steering started out as a way to keep model sail boats on course. Before the advent of radio control, model yacht racing (started before WW1) was typically contested on long narrow ponds, and the number of stops along the banks was counted as a penalty in the final result. Initially a system of counterweight on the tillers was devised to compensate for the weather helm when the model boat heeled in a gust. These crude systems evolved in a more sophisticated system called Braine Gear after its inventor, George Braine. The Braine steering gear was a fine-tuned system of quadrant on the rudder stock driven by the tension of the mainsail sheet and damped by a rubber band. A more sophisticated system called the vane gear was later devised, it relied on a small vane or airfoil driving the main rudder via an adjustable sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Course (navigation)
In navigation, the course of a watercraft or aircraft is the cardinal direction in which the craft is to be steered. The course is to be distinguished from the ''heading'', which is the direction where the watercraft's bow or the aircraft's nose is pointed. Course, track, route and heading The path that a vessel follows over the ground is called a ''ground track'', ''course made good'' or ''course over the ground''. For an aircraft it is simply its ''track''. The intended track is a ''route''. For ships and aircraft, routes are typically straight-line segments between waypoints. A navigator determines the ''bearing'' (the compass direction from the craft's current position) of the next waypoint. Because water currents or wind can cause a craft to drift off course, a navigator sets a ''course to steer'' that compensates for drift. The helmsman or pilot points the craft on a ''heading'' that corresponds to the course to steer. If the predicted drift is correct, then the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chartplotter
A Chartplotter is a device used in marine navigation that integrates GPS data with an electronic navigational chart (ENC). The chartplotter displays the ENC along with the position, heading and speed of the ship, and may display additional information from radar, automatic information systems (AIS) or other sensors. As appropriate to particular marine applications, chartplotters may also display data from other sensors, such as echolocators or sonar. Technology Electronic chartplotters are by nature CPU (and GPU) intensive applications. Chartplotters need to retrieve the Navigation Signal (Galileo, GPS, GLONASS, WAAS etc.) and overlay that on a map. Map updates on dedicated hardware typically have screen refresh rates from 5 Hz to 30 Hz. Some navigation software can run on standard computers (and mobile phones, etc.) but most higher end systems are dedicated hardware. Especially when the chartplotter generates three-dimensional displays, as used for fishing, conside ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moment Of Force
In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment of force (also abbreviated to moment). It represents the capability of a force to produce change in the rotational motion of the body. The concept originated with the studies by Archimedes of the usage of levers, which is reflected in his famous quote: "''Give me a lever and a place to stand and I will move the Earth''". Just as a linear force is a push or a pull, a torque can be thought of as a twist to an object around a specific axis. Torque is defined as the product of the magnitude of the perpendicular component of the force and the distance of the line of action of a force from the point around which it is being determined. The law of conservation of energy can also be used to understand torque. 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 . In th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pendulum
A pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced sideways from its resting, equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the equilibrium position. When released, the restoring force acting on the pendulum's mass causes it to oscillate about the equilibrium position, swinging back and forth. The time for one complete cycle, a left swing and a right swing, is called the period. The period depends on the length of the pendulum and also to a slight degree on the amplitude, the width of the pendulum's swing. From the first scientific investigations of the pendulum around 1602 by Galileo Galilei, the regular motion of pendulums was used for timekeeping and was the world's most accurate timekeeping technology until the 1930s. The pendulum clock invented by Christiaan Huygens in 1658 became the world's standard timekeeper, used in homes and offices for 270 years, and ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herbert Hasler
Herbert George "Blondie" Hasler (27 February 1914 – 5 May 1987) was a Lieutenant Colonel in the Royal Marines. In December 1942, Hasler led a small commando raid in World War II against Axis shipping in Bordeaux. He was responsible for many of the concepts which ultimately led to the post-war formation of the Special Boat Service. After the war he became a notable yachtsman, contributing especially to developments in single-handed sailing. Early life Hasler was born in Dublin on 27 February 1914, the youngest son of Lieutenant Arthur Thomas Hasler (a Royal Army Medical Corps quartermaster), and his wife, Annie Georgina (née Andrews). His father died after the troopship ''Transylvania'' was torpedoed on 4 May 1917. Hasler was sent to Wellington College, where he was a keen sportsman. He was commissioned into the Royal Marines on 1 September 1932. Second World War In 1940, Hasler served as fleet landing officer in Scapa Flow, and was then sent to Narvik in support of the Frenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Windmill Fantail
A fantail is a small windmill mounted at right angles to the sails, at the rear of the windmill, and which turns the cap automatically to bring it into the wind. The fantail was patented in 1745 by Edmund Lee, a blacksmith working at Brockmill Forge near Wigan, England, and was perfected on mills around Leeds and Hull towards the end of the 18th century. Fantails are found on all types of traditional windmills and are especially useful where changes in wind direction are frequent. They are more common in England, Denmark and Germany than in other parts of Europe, and are little-known on windmills elsewhere except where English millwrighting traditions were in evidence. The rotating fantail turns the cap of the windmill via a system of gearing to a toothed rack around the top of the mill tower, or to wheels running on the ground in the case of a post mill The post mill is the earliest type of European windmill. Its defining feature is that the whole body of the mill that houses ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Windmill
A windmill is a structure that converts wind power into rotational energy using vanes called windmill sail, sails or blades, specifically to mill (grinding), mill grain (gristmills), but the term is also extended to windpumps, wind turbines, and other applications, in some parts of the English speaking world. The term wind engine is sometimes used to describe such devices. Windmills were used throughout the High Middle Ages, high medieval and early modern periods; the horizontal or panemone windmill first appeared in Persia during the 9th century, and the vertical windmill first appeared in northwestern Europe in the 12th century. Regarded as an icon of Culture of the Netherlands, Dutch culture, there are approximately 1,000 windmills in the Netherlands today. Forerunners Wind-powered machines may have been known earlier, but there is no clear evidence of windmills before the 9th century. Hero of Alexandria (Heron) in first-century Roman Egypt described what appears to be a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trim Tab
Trim tabs are small surfaces connected to the trailing edge of a larger control surface on a boat or aircraft, used to control the trim of the controls, i.e. to counteract hydro- or aerodynamic forces and stabilise the boat or aircraft in a particular desired attitude without the need for the operator to constantly apply a control force. This is done by adjusting the angle of the tab relative to the larger surface. Changing the setting of a trim tab adjusts the neutral or resting position of a control surface (such as an elevator or rudder). As the desired position of a control surface changes (corresponding mainly to different speeds), an adjustable trim tab will allow the operator to reduce the manual force required to maintain that position—to zero, if used correctly. Thus the trim tab acts as a servo tab. Because the center of pressure of the trim tab is farther away from the axis of rotation of the control surface than the center of pressure of the control surface, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Servo Tab
__NOTOC__ A servo tab is a small hinged device installed on an aircraft control surface to assist the movement of the control surfaces. Introduced by the German firm Flettner, servo tabs were formerly known as Flettner tabs. Servo tabs are not true servomechanisms, as they do not employ negative feedback to keep the control surfaces in a desired position; they only provide a mechanical advantage to the pilot. Servo tabs A servo tab, or balance tab, moves in the direction opposite to the desired movement of the control surface. It deflects airflow, generating force on the whole control surface in the desired direction. The tab has a leverage advantage, being located well aft of the control surface hinge line, and thus its airflow deflection moves the control surface in the opposite direction, overcoming the resistance generated by the airflow deflection of the control surface. This has the effect of reducing the control force required from the pilot to move the controls. In som ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apparent Wind
Apparent wind is the wind experienced by a moving object. Definition of apparent wind The ''apparent wind'' is the wind experienced by an observer in motion and is the relative velocity of the wind in relation to the observer. The ''velocity of the apparent wind'' is the vector sum of the ''velocity of the headwind'' (which is the velocity a moving object would experience in still air) plus the ''velocity of the true wind''. The headwind is the additive inverse of the object's velocity; therefore, the ''velocity of the apparent wind'' can also be defined as a vector sum of the ''velocity of the true wind'' minus the ''velocity of the object''. Apparent wind in sailing In sailing, ''apparent wind'' is the speed and direction of wind indicated by a wind instrument (anemometer) on a ''moving'' craft (on water, land or ice) in undisturbed air. It is composed of the ''combined'' speeds and directions of the craft and wind observed by a ''stationary'' wind instrument—the ''true w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Windvane Self Steering System
A wind vane, weather vane, or weathercock is an instrument used for showing the direction of the wind. It is typically used as an architectural ornament to the highest point of a building. The word ''vane'' comes from the Old English word , meaning "flag". Although partly functional, wind vanes are generally decorative, often featuring the traditional cockerel design with letters indicating the points of the compass. Other common motifs include ships, arrows, and horses. Not all wind vanes have pointers. In a sufficiently strong wind, the head of the arrow or cockerel (or equivalent) will indicate the direction from which the wind is blowing. Wind vanes are also found on small wind turbines to keep the wind turbine pointing into the wind. History The oldest textual reference in China to a weather vane comes from the ''Huainanzi'' dating from around 139 BC, which mentions a thread or streamer that another commentator interprets as "wind-observing fan" (, ). The Tower of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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