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32-point compass rose. The points of the compass are a set of horizontal, radially arrayed compass directions (or azimuths) used in navigation and cartography.A compass rose is primarily composed of four cardinal directions—north, east, south, and west—each separated by 90 degrees, and secondarily divided by four ordinal (intercardinal) directions—northeast, southeast, southwest, and ...
Direction determination refers to the ways in which a cardinal direction or compass point can be determined in navigation and wayfinding.The most direct method is using a compass (magnetic compass or gyrocompass), but indirect methods exist, based on the Sun path (unaided or by using a watch or sundial), the stars, and satellite navigation.
Thus, 32 points of 11.25° each makes a circle of 360°. An object at 022.5° relative would be 'two points off the starboard bow', an object at 101.25° relative would be 'one point abaft the starboard beam' and an object at 213.75° relative would be 'three points on the port quarter'. This method is only used for a relative bearing.
A lubber line, which can be a marking on the compass bowl or a small fixed needle, indicates the ship's heading on the compass card. Traditionally the card is divided into thirty-two points (known as rhumbs ), although modern compasses are marked in degrees rather than cardinal points.
4 - Compass north, including a two-part error; the magnetic variation (6) and the ship's own magnetic field (5) 5 - Magnetic deviation, caused by vessel's magnetic field. 6 - Magnetic variation, caused by variations in Earth's magnetic field. 7 - Compass heading or compass course, before correction for magnetic deviation or magnetic variation.
Naming all 32 points on the rose is called "boxing the compass". The 32-point rose has 11 1 ⁄ 4 ° between points, but is easily found by halving divisions and may have been easier for those not using a 360° circle. Eight points make a right angle and a point is easy to estimate allowing bearings to be given such as "two points off the ...
On a Mercator projection map, any rhumb line is a straight line; a rhumb line can be drawn on such a map between any two points on Earth without going off the edge of the map. But theoretically a loxodrome can extend beyond the right edge of the map, where it then continues at the left edge with the same slope (assuming that the map covers ...
Direction determination refers to the ways in which a cardinal direction or compass point can be determined in navigation and wayfinding.The most direct method is using a compass (magnetic compass or gyrocompass), but indirect methods exist, based on the Sun path (unaided or by using a watch or sundial), the stars, and satellite navigation.