What are the principles and characteristics of Marine magnetic compass?

The magnetic compass is a pointing instrument made by the principle that the magnetic needle can point to the magnetic north (south) pole of the earth under the action of the earth's magnetic force. The magnetic compass has been installed and used on marine ships as an important navigation instrument for a long time. At present, although modern ships are equipped with gyroscopes (electric compasses), satellite navigation (GPS) and other navigation instruments, modern magnetic compasses are still installed and used as navigation instruments on marine ships because of their simple structure, reliable performance and independence from external conditions. The Maritime Organization (IMO), classification societies, and ship inspection agencies of various countries have clearly stipulated that marine ships should be equipped with magnetic compasses, and the deviation should be correctly corrected and a deviation table should be prepared.

1 Classification of magnetic compasses

a According to whether there is liquid in the magnetic compass basin, there are two types: liquid compass and dry compass. The compass of the liquid compass is suspended in the compass basin filled with liquid. Due to the damping effect of the liquid, the compass has better stability when the ship sways. In addition, due to the buoyancy of the liquid, the friction between the compass support shaft needle and the bearing can be reduced, thereby improving the sensitivity of the compass basin. Our company's products are all liquid compasses.

b According to the purpose of magnetic compasses, there are mainly standard compasses and steering compasses. Standard compasses are generally vertical and installed on the top deck of the cab (compass deck). Because of its high position, no shelter, and little influence by the ship's magnetism, it is used to observe the course and determine the direction of the target and calibrate the steering compass, so it is called a standard compass.

Steering compasses are generally desktop, installed in the cab, and used to observe the course and steer. Our company produces various types of standard compasses and steering compasses.

c According to the diameter of the compass disk, the commonly used ones are 190mm, 165mm, 130mm, and 100mm.

2 Magnetic compass deviation and correction

Steel ships will generate ship magnetism due to the magnetization of the earth's magnetic field, which will affect the pointing accuracy of the magnetic compass, the so-called "deviation". This deviation can be corrected by the compass master. The magnetic compasses produced by our company are equipped with a deviation correction device.

3 Installation of magnetic compass

a The magnetic compass should be installed on the longitudinal centerline of the ship as much as possible, and the * line of the compass cabinet should coincide with (or be parallel to) the longitudinal centerline of the ship.

b The minimum distance between the standard magnetic compass and any ferromagnetic material is 1 meter.

4 Daily maintenance of magnetic compass

a The magnetic compass should be covered with a compass cap (the standard compass should be covered with a compass cover).

b Keep the liquid in the compass bowl colorless and transparent, and eliminate bubbles.

c Keep the compass bowl axis and the gimbal axis lubricated and flexible.

d Regularly check the half-cycle and sensitivity of the compass, and refill the compass bowl when necessary.

e No magnetic objects should be placed near the compass, and the compass should not be kept in a high temperature or vibration environment for a long time.