Question 15 AB01 - Able Seafarer

The Correct Answer is C **Why option C is correct:** The magnetic compass operates based on the fundamental principle that a magnetized needle will align itself with the Earth's magnetic field. This mechanism requires very few moving parts—primarily just the compass card/needle assembly suspended in liquid (or on a pivot). Because it lacks complex electronics, power sources, or intricate mechanical systems, the magnetic compass is exceptionally robust, requires minimal maintenance, and is therefore highly reliable, especially in adverse conditions where electronic systems might fail. Its "essential simplicity" is its key advantage for reliability aboard vessels. **Why the other options are incorrect:** * **A) All points on the compass rose are readily visible.** While the compass card is designed for readability, this feature is characteristic of virtually all navigational compasses (magnetic, gyro, or electronic repeaters) and is a design standard, not a unique advantage of the magnetic type itself. * **B) Compass error is negligible at or near the earth's magnetic poles.** This is factually incorrect. The reliability and accuracy of the magnetic compass decrease drastically as a vessel approaches the magnetic poles. Near the poles, the horizontal component of the Earth's magnetic field (which the compass needs to align with) weakens, while the vertical component strengthens, causing the needle to dip, making the compass unstable and unreliable. * **D) It does not have to be checked as often.** A magnetic compass must be checked regularly, both for deviation (errors caused by the vessel's own metal and electrical systems) and for the integrity of its liquid, suspension, and physical mounting. While it may require less *technical* maintenance than a complex gyrocompass, it must be continuously monitored and compensated for accurate navigation.