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Lubber Line
A lubber line, also known as a lubber's line, is a fixed line on a compass binnacle or radar plan position indicator display pointing towards the front of the ship or aircraft and corresponding to the craft's centerline (being the customary direction of movement). The line represents 0 degrees and is therefore the zero-point from which relative bearings are measured, e.g., "''twenty degrees to port''". Compasses on sailboats may have additional lubber lines at forty-five degrees from the centerline. This represents about as close to the wind as the average boat will sail. These lubber lines may be used when sailing close hauled A point of sail is a sailing craft's direction of travel under sail in relation to the true wind direction over the surface. The principal points of sail roughly correspond to 45° segments of a circle, starting with 0° directly into the wind. ... to see if you are on the closest course to your destination, without having to add or subtract the 45 d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compass
A compass is a device that shows the cardinal directions used for navigation and geographic orientation. It commonly consists of a magnetized needle or other element, such as a compass card or compass rose, which can pivot to align itself with magnetic north. Other methods may be used, including gyroscopes, magnetometers, and GPS receivers. Compasses often show angles in degrees: north corresponds to 0°, and the angles increase clockwise, so east is 90°, south is 180°, and west is 270°. These numbers allow the compass to show azimuths or bearings which are commonly stated in degrees. If local variation between magnetic north and true north is known, then direction of magnetic north also gives direction of true north. Among the Four Great Inventions, the magnetic compass was first invented as a device for divination as early as the Chinese Han Dynasty (since c. 206 BC), Li Shu-hua, p. 176 and later adopted for navigation by the Song Dynasty Chinese during the 11th ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binnacle
A binnacle is a waist-high case or stand on the deck of a ship, generally mounted in front of the helmsman, in which navigational instruments are placed for easy and quick reference as well as to protect the delicate instruments. Its traditional purpose was to hold the ship's magnetic compass, mounted in gimbals to keep it level while the ship pitched and rolled. A binnacle may be subdivided into sections and its contents typically include one or more compasses and an oil lamp or other light source. Other devices such as a sand timer for estimating speed may have been stored in the binnacle as well. Binnacle can also refer to the cluster of instruments and switches mounted in a circular casing on or near the steering column of a car. History The construction of many early (mid-18th century) binnacles used iron nails, which were later discovered to cause magnetic deviations in compass readings. As the development of the compass and understanding of magnetism progressed, gre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radar
Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna (often the same antenna is used for transmitting and receiving) and a receiver and processor to determine properties of the objects. Radio waves (pulsed or continuous) from the transmitter reflect off the objects and return to the receiver, giving information about the objects' locations and speeds. Radar was developed secretly for military use by several countries in the period before and during World War II. A key development was the cavity magnetron in the United Kingdom, which allowed the creation of relatively small systems with sub-meter resolution. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plan Position Indicator
A plan position indicator (PPI) is a type of radar display that represents the radar antenna in the center of the display, with the distance from it and height above ground drawn as concentric circles. As the radar antenna rotates, a radial trace on the PPI sweeps in unison with it about the center point. It is the most common type of radar display. Description The radar antenna sends pulses while rotating 360 degrees around the radar site at a fixed elevation angle. It can then change angle or repeat at the same angle according to the need. Return echoes from targets are received by the antenna and processed by the receiver and the most direct display of those data is the PPI. The height of the echoes increases with the distance to the radar, as represented in the adjacent image. This change is not a straight line but a curve as the surface of the Earth is curved and ''sinks'' below the radar horizon. For fixed-site installations, north is usually represented at the top of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Degree (angle)
A degree (in full, a degree of arc, arc degree, or arcdegree), usually denoted by ° (the degree symbol), is a measurement of a plane angle in which one full rotation is 360 degrees. It is not an SI unit—the SI unit of angular measure is the radian—but it is mentioned in the SI brochure as an accepted unit. Because a full rotation equals 2 radians, one degree is equivalent to radians. History The original motivation for choosing the degree as a unit of rotations and angles is unknown. One theory states that it is related to the fact that 360 is approximately the number of days in a year. Ancient astronomers noticed that the sun, which follows through the ecliptic path over the course of the year, seems to advance in its path by approximately one degree each day. Some ancient calendars, such as the Persian calendar and the Babylonian calendar, used 360 days for a year. The use of a calendar with 360 days may be related to the use of sexagesimal numbers. Another ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Port (nautical)
Port and starboard are nautical terms for watercraft and aircraft, referring respectively to the left and right sides of the vessel, when aboard and facing the bow (front). Vessels with bilateral symmetry have left and right halves which are mirror images of each other. One asymmetric feature is where access to a boat, ship, or aircraft is at the side, it is usually only on the port side (hence the name). Side Port and starboard unambiguously refer to the left and right side of the vessel, not the observer. That is, the port side of the vessel always refers to the same portion of the vessel's structure, and does not depend on which way the observer is facing. The port side is the side of the vessel which is to the left of an observer aboard the vessel and , that is, facing forward towards the direction the vehicle is heading when underway, and starboard side is to the right of such an observer. This convention allows orders and information to be given unambiguously, wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Close Hauled
A point of sail is a sailing craft's direction of travel under sail in relation to the true wind direction over the surface. The principal points of sail roughly correspond to 45° segments of a circle, starting with 0° directly into the wind. For many sailing craft 45° on either side of the wind is a ''no-go'' zone, where a sail is unable to mobilize power from the wind. Sailing on a course as close to the wind as possible—approximately 45°—is termed ''beating'', a point of sail when the sails are ''close-hauled''. At 90° off the wind, a craft is on a ''beam reach''. The point of sail between beating and a beam reach is called a ''close reach''. At 135° off the wind, a craft is on a ''broad reach''. At 180° off the wind (sailing in the same direction as the wind), a craft is ''running downwind''. A given point of sail (beating, close reach, beam reach, broad reach, and running downwind) is defined in reference to the true wind—the wind felt by a stationary observe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Landlubber
In English-speaking popular culture, the modern pirate stereotype owes its attributes mostly to the imagined tradition of the 18th century Caribbean pirate sailing off the Spanish Main and to such celebrated 20th century depictions as Captain Hook and his crew in the theatrical and film versions of J. M. Barrie's children's book ''Peter Pan'', Robert Newton's portrayal of Long John Silver in the 1950 film adaptation of the Robert Louis Stevenson novel ''Treasure Island'', and various adaptations of the Middle Eastern pirate, ''Sinbad the Sailor''. In these and countless other books, films, and legends, pirates are portrayed as "swashbucklers" and " plunderers". They are shown on ships, often wearing eyepatches or peg legs, having a parrot perched on their shoulder, and saying phrases like "Arr, matey" and "Avast, me hearty". Pirates have retained their image through pirate-themed tourist attractions, film, toys, books and plays. Origins The characteristics of pirates in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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