Global Compass - how do they work
The Map Reading Company The Map Reading Company
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 Published On Apr 8, 2024

While standard compasses may experience limitations such as needle dragging and erratic behaviour in regions with strong magnetic dips, global compasses have a separate magnet and north-seeking pointer to ensure consistent and reliable performance under various magnetic conditions.

Standard Compass:
• In a standard compass, the North Seeking Pointer is typically a magnetized strip or disk made of a ferromagnetic material like steel.
• The magnetic needle is rigidly attached to the base or housing of the compass, typically by a pivot point.
• As the compass moves towards the magnetic poles (either the North Magnetic Pole or the South Magnetic Pole), the magnetic field lines become more vertical, causing the needle to dip or incline.
• When the needle dips too far due to the strong inclination of the magnetic field lines, it may drag or rub against the base of the compass housing. This friction can impede the smooth rotation of the needle and affect the accuracy of direction readings.
• Additionally, in extreme northern or southern latitudes, where the magnetic field lines are nearly vertical, standard compasses may exhibit erratic behaviour or become unreliable due to the excessive dipping of the needle.


Global Compass:
• In contrast, a global compass is specifically designed to mitigate the limitations associated with standard compasses, particularly in regions with extreme magnetic inclination.
• In a global compass, the North Seeking Pointer is attached to a small magnet in a unique manner that allows the magnet to tilt or dip without significantly affecting the orientation of the Pointer.
• By allowing the magnet to dip freely, the global compass can compensate for the vertical inclination of the magnetic field lines, ensuring that the Pointer remains relatively stable and accurate even in regions with strong magnetic dips.
• This design feature minimizes the risk of the needle dragging against the base of the compass housing, thereby maintaining smooth rotation and precise direction readings.
• Consequently, global compasses are better suited for navigation in diverse geographical locations, including polar regions, where standard compasses may struggle due to magnetic anomalies and extreme magnetic inclinations.

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