In the previous several passages, a study of the power engineering was thoroughly made. From now on, a concise introduction concerning the light current engineering will be presented to you, which deals with the equipment for navigation, communication, observation and detection. Indeed, the above equipment can well boast itself to be the ears and eyes of a ship. In the first place, we will come to the navigation equipment.
1. Compass
The compass is the chief instrument on board to indicate the course of a ship, which may be subdivided into magnetic compass and electrical compass in the light of their different working principles.
The magnetic compass is a sort of directional instruments, the long history of which might date back to the ancient Chinese and the principle of which is that a magnetic needle will always point to the North Pole due to the influence of the earth magnetic field.
In spite of the fact that a lot more navigation equipment of high accuracy has been invented, the magnetic compass could not be spared yet by reason of its simplicity of construction, reliability of performance, convenience of application and independence of power supply. Just as everything in the world has two sides, however, the magnetic compass cannot avoid certain weak-points of its own, that is, the accuracy of the magnetic compass is not as ideal as people might expect, since its pointing of direction will be affected both by the external magnetic field Which has been slowly varying with the passage of time and by the magnetic objects around it.
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