What Is The Compass On Modern Ships? Does The Ancient Magnetic Compass Still Work?Ⅱ
Oct 17, 2020| Later, with the development of ships, wooden sailboats entered the era of steel ships. A large number of steel and cables were used, which also made the ship magnetic.
The accumulated magnetism of the ship hull has a negative effect on the magnetic compass, which brings a new kind of deviation self deviation.
The difference between the magnetic needle and the magnetic north is also different. The maximum difference between them can reach tens of degrees.
Therefore, modern ships should often correct the self deviation, and then compile the residual deviation into the deviation table or self deviation curve. For the crew to consult the calculation in actual use, get the true north direction.
1. Magnetic compass can be divided into dry compass and liquid compass according to their structures. Dry compass has been eliminated, and liquid magnetic compass is mainly used in modern ships.
The basin of the liquid compass is installed on the universal balance ring, which can keep the level during the ship shaking. The basin is sealed with a mixture of alcohol and distilled water.
The compass floats in the liquid. The buoyancy reduces the friction resistance, increases the pointing stability, and greatly improves the sensitivity.
2. It can be divided into standard compass, steering compass and emergency compass according to different installation positions and uses.
Among them, the standard compass is installed on the open compass deck above the cab; the steering compass is in the cab for steering; and the emergency compass is provided for emergency steering in front of the emergency rudder at the stern.
Magnetic compass has always been accompanied by human navigation. It can be used in all kinds of situations, but its accuracy is poor.
In 1850's, people invented gyrocompass based on the principle of gyroscope. Gyrocompass, also known as gyrocompass, is driven by electricity.
The gyro with high-speed rotation has the characteristics of fixed axis and precession.
When the gyrocompass is started, the rotation axis of the gyro rotor points to the true north direction under the influence of the earth's angular velocity and gravity.
It is not affected by sound, light, electricity, magnetism and other factors. It is very accurate and has strong applicability. It is widely used in ships, aircraft, missiles and other equipment.
Compared with magnetic compass, gyrocompass is more accurate, less error, free from magnetic interference, wide installation range, and can be connected with multiple repeaters.
But its system is complex, reliability is a little poor, need power supply, once power failure or failure can not be used. Therefore, modern ships are equipped with two kinds of compass at the same time, in case of emergency.
To sum up, with the help of various advanced navigation equipment, the safety of modern ships in the dense navigation of the world's oceans has increased by many times compared with the ancient times. But the ancient magnetic compass still firmly occupies a place and continues to play its unique role.