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A Flinders bar is a vertical soft iron bar placed in a tube on the fore side of a compass binnacle. The Flinders bar is used to counteract the vertical magnetism inherent within a ship and is usually calibrated as part of the process known as swinging the compass , where deviations caused by this inherent magnetism are negated by the use of ...
Isoclinic lines for the year 2020. Magnetic dip results from the tendency of a magnet to align itself with lines of magnetic field. As Earth's magnetic field lines are not parallel to the surface, the north end of a compass needle will point upward in the Southern Hemisphere (negative dip) or downward in the Northern Hemisphere (positive dip).
A fluxgate inclinometer/compass. The basic fluxgate compass is a simple electromagnetic device that employs two or more small coils of wire around a core of highly permeable magnetic material, to directly sense the direction of the horizontal component of the Earth'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. 8 - Magnetic heading, the compass heading corrected for magnetic deviation but not magnetic variation; thus, the heading reliative to magnetic north.
Some more expensive heading indicators are "slaved" to a magnetic sensor, called a flux gate. The flux gate continuously senses the Earth's magnetic field, and a servo mechanism constantly corrects the heading indicator. [4] These "slaved gyros" reduce pilot workload by eliminating the need for manual realignment every ten to fifteen minutes.
The Earth's natural magnetic forces are considerably weak, measuring at 0.5 gauss and magnetic fields from household electronics can easily exceed it, overpowering the compass needle. Exposure to strong magnets, or magnetic interference can sometimes cause the magnetic poles of the compass needle to differ or even reverse.
A sample compass correction card, showing the deviation correction for a given heading. Once the compass has been corrected using small magnets fitted in the base and with soft iron balls, any residual deviation is recorded as a table or graph: the compass correction card, which is kept on board near the compass. [6]
Bearing compass used to determine magnetic bearings of landmarks, other ships or celestial bodies. Magnetic compass used to determine the magnetic heading of the ship.