Magnetic Compass Principle And Characteristics

The  magnetic compass is a kind of pointing instrument made of the principle  that the magnetic needle can point to the north (south) pole of the  earth magnetic field under the action of magnetic force. As an important navigation instrument, magnetic compasses have been used in marine ships for a long time. At  present, although modern ships have been equipped with advanced  navigation instruments such as gyroscopes and GPS, modern magnetic  compasses are still necessary as they have a simple structure, reliable  performance, and do not depend on external conditions. Navigation instruments are installed and used by marine vessels. The  International Maritime Organization (IMO), classification societies,  and ship surveying agencies of various countries have clearly stipulated  that marine vessels should be equipped with magnetic compasses and  should be properly calibrated for deviations and preparedness.

    1 Magnetic compass classification
a  According to whether or not there is a liquid component in the magnetic  compass, there are two kinds of liquid compass and dry compass. The  compass of the liquid compass is suspended in a liquid filled bowl. Due  to the damping effect of the liquid, the stability of the compass is  good when the ship is swaying. In  addition, due to the buoyant action of the liquid, the friction between  the compass support shaft pin and the bearing can be reduced, thereby  increasing the sensitivity of the pot. The company's products are liquid compasses.
b According to the use of magnetic compass points, there are standard compasses, steering compasses. Standard compasses are generally vertical and are mounted on the top deck (compass) of the cab. Due  to its high position and no obstruction, it is affected by the ship's  magnetism. It is used to observe the heading, measure the object  orientation, and correct steering compasses. It is called the standard  compass.
Steer compasses are generally bench top mounted in the cab for observation of course and steering. The company produces standard compasses and steering compasses for each model.
c According to the compass disk diameter, commonly used 190mm, 165mm, 130mm, 100mm.

    2 magnetic compass deviation and correction
Steel  ships are magnetized by the earth's magnetic field, which can affect  the accuracy of the magnetic compass, the so-called "self-difference." This deviation can be corrected by the compass teacher. The magnetic compass produced by our company is equipped with a high-efficiency self-difference correction device.

    3 Magnetic compass installation
a  The magnetic compass should be installed on the longitudinal centerline  of the ship as much as possible. The first line of the compass cabinet  should be coincident (or parallel) with the longitudinal median line of  the ship.
b The minimum distance between a standard magnetic compass and any ferromagnetic substance is 1 meter.
4 Routine Maintenance of Magnetic Compass
a The magnetic compass should be covered with a compass cap (the standard compass should be covered with a compass sleeve).
b Keep the liquid inside the pot clear and colorless and eliminate bubbles.
c Keep the shaft of Luopan, lubrication of Changping ring shaft, flexible rotation.
d Periodically check the half cycles of the compass, sensitivity, and rehydration of the pots if necessary.
e  No magnetic objects should be placed near the compass, and the compass  should not be exposed to high temperatures and vibration for a long  time.