Magnetic compass

A magnetic compass is a north-seeking instrument whose magnetized needles align with the horizontal component of Earth’s magnetic field, giving heading relative to magnetic north. The card floats in a damping fluid inside a gimballed bowl seated in a binnacle, with soft-iron and permanent-magnet correctors fitted to reduce deviation. SOLAS Chapter V Reg 19 requires every ship to carry a properly adjusted standard magnetic compass independent of any power supply, plus a means of taking bearings over 360 degrees. Construction and performance follow ISO 25862:2019, which replaced the older ISO 449. The standard compass remains the backup heading reference when the gyrocompass or electronic systems fail.