A compass is the most important instrument for sailors. It is used by sailors to identify directions in the frame of reference. The four directions such as north, south, east, west, and the other intermediate directions are also shown in the frame of reference. There are also angles marked in the frame in degrees. Directions are marked clockwise in the order of north, east, south, west and so the angle marking of zero degree corresponds to north, 90 degrees to east, 180 degrees to south and 270 to west.
There are two different types of compass, magnetic compass, and gyro compass. The former one contains a magnet and it interacts with the magnetic field of the earth and points to the magnetic poles by aligning itself to it. The latter one, gyro compass contains a rapidly spinning wheel. Its rotation interacts with the earth’s rotation in a dynamic way so that the wheel moves, loses energy and makes its axis of rotation parallel with the earth’s.
Importance
A compass, discovered by Chinese and initially used by Europeans is used to determine the geographical area. Its importance as a navigational device are numerous. It does not require any power source for its operation. Some of its main features are
a. Portablility
The compass being portable is one of its important benefits. It never adds to additional weight due to its slim and compact nature. Compasses fit in your pocket most of the times. You can also hang them around your neck fitting straps to it.
b. Advantage over GPS
GPS equipments work and find the direction the boat is facing only when they are in motion. Where as compasses work even when they are not moving.
c. Inexpensive
Marine Compasses, which prove as an effective equipment for, are relatively inexpensive these days.
d. Advantage over transit
Though a GPS gives more accurate reading faster than a compass, compasses have more advantage over a transit which might even take 10 to 15 minutes with no real advantage in accuracy.
e. Self sufficiency
Having a compass with you makes you completely self sufficient and lets you travel happily to any place with no worry for a power source or the assistance of another person, just by possessing a compass and recording the correct direction.
f. Navigation
Navigation from a known direction to other places is one use of compass. apart from that navigating from an unknown place is one another major importance of a compass. you can assume two range points from your current position, using the map and drawing lines , and finding the angles you can find your current position by using the intersection point of the lines.
Other advantages
Marine compasses can also be used with a sighter, a tool used to measure objects on the horizon, to calculate latitude. Can be used with a time keeping tool called a marine chronometer to determine longitude and also can be used to take detours.