In the vast expanse of the ocean, ships rely on precise navigation tools to avoid getting lost.

The compass, an essential navigation device, serves as a ship's "guiding light."

Here, Lykkers, we explore the four main types of compasses used in maritime navigation: magnetic compass, gyrocompass, fiber optic compass, and satellite compass.

Magnetic Compass

The magnetic compass is a traditional navigation device that uses the earth's magnetic field to indicate geographical orientation and the ship's heading. It comprises two primary components: a compass bowl and a compass cabinet.

Depending on its structure, the magnetic compass is categorized into liquid and dry types. The liquid compass, with its pointing system immersed in a mixture of alcohol and distilled water, offers superior directionality and stability.

In contrast, the dry compass, which lacks a liquid immersion system, has poorer directionality and is gradually being phased out.

The magnetic compass can also be classified based on its installation location and scope of use. The standard compass is usually installed at the ship's main rudder position, providing accurate heading information.

The steering compass assists with navigation and is typically located near the rudder. The emergency compass acts as a backup when the main compass fails. Finally, the lifeboat compass is installed on lifeboats to ensure accurate navigation in emergencies.

Gyrocompass

The gyrocompass, also known as the electrically controlled gyrocompass, applies gyroscopic principles to ship navigation.

When the gyro rotor spins at high speed without any external torque, its rotational axis remains stable in inertial space, a characteristic known as the gyro's fixed axis. If external torque is applied to another axis, the gyro's rotation direction becomes perpendicular to the torque direction, a property called precession.

By leveraging the gyro's fixed axis and precession, the gyrocompass's rotation axis can precisely track the earth's meridian plane, always pointing to the geographic North Pole and thus determining the ship's heading.

Compared to the magnetic compass, the gyrocompass offers higher accuracy and stability, especially in areas with strong magnetic field interference.

Fiber Optic Compass

Introduced in the late 1990s, the fiber optic compass uses optical fibers wound into a gyro ball. This modern device boasts several advantages over traditional gyrocompasses: quick start-up, compact size, lightweight, minimal rapid steering error, no swing error, and a wide operational geographical range.

The fiber optic compass requires no special installation environment and is easy to set up. Its lack of moving parts makes it straightforward to operate and maintain, with lower costs, making it suitable for various types of ships.

However, the heading indication of the fiber optic compass is closely tied to the precise longitude and latitude of its location. Therefore, it requires integration with satellite positioning (GNSS) signals or odometer signals to obtain accurate geographical data.

Satellite Compass

The satellite compass consists of an antenna unit, a display unit, and a processing unit. Its operation involves two satellite positioning receivers that capture radio wave information from the same satellite.

By extracting pseudorange and phase parameters, the main processing unit calculates the distance difference between the satellite and the two receivers. This data determines the baseline direction connecting the two receivers, ultimately providing the ship's heading.

Satellite compasses offer several benefits: ultra-fast start-up, quick tracking, absence of mechanical parts, maintenance-free operation, and no recurring costs. Despite these advantages, satellite compasses and fiber optic compasses cannot yet fully replace magnetic and gyrocompasses.

Their reliance on external signal input, rather than internal mechanisms, to obtain accurate heading information limits their standalone functionality in maritime navigation.

The diverse functionalities of magnetic, gyro, fiber optic, and satellite compasses complement each other, providing comprehensive solutions for maritime navigation.

In Conclusion

By understanding and utilizing these different types of compasses, ships can navigate the vast oceans safely and efficiently, minimizing the risk of getting lost.

The integration of traditional and modern navigation tools ensures that ships can maintain accurate courses, regardless of external conditions or technological dependencies.