The compass is the only aid permitted to help with orienteeringn, although it is not mandatory. For example, at various stages of young people’s training it is important not to use a compass.
A compass is a device with a magnetic needle that is attracted to the Earth’s magnetic pole. Athletes use it to orient the map to the north by matching the compass needle with the north lines on the map.
Maps are produced oriented to magnetic north rather than geographic north. As such, during a course, athletes do not have to make any corrections to compensate for the difference between the two.
There are compasses suitable for competition that are carried attached to the finger and directly on top of the map. However, any type of compass can be used.
In the southern hemisphere, compasses must be different from those used in the northern hemisphere, due to the different influence of the Earth’s magnetic field between the two hemispheres.
The magnetic poles
The phenomenon that makes the compass needle point in the North-South direction is the terrestrial magnetism. The Earth is like a giant magnet. Although magnetism was discovered a long time ago, its use as an orientation aid is much more recent.
Origin of the compass
The Chinese were probably the first to explore the phenomenon of magnetism to indicate North (or South). “Si Nan” (Si = “Point to”; Nan = “South”) is considered the first compass and consists of a magnetic stone, carved in the shape of a shell, whose handle points to the South.
According to some Chinese writings, the first compasses (developed from the “Si Nan”) were used at sea around the year 850. The invention was then spread to the West by astronomers and cartographers.
The compass was developed over the centuries and experienced considerable advancement when it was discovered that a thin piece of metal (needle) could be magnetized and could then be wrapped and enclosed in a transparent, air-filled casing, thus protecting the needle.
Initially, compass needles took a long time to stabilize. Modern compasses are precision instruments and their needle, now usually enclosed in a liquid-filled casing, quickly points north (or south in the Southern Hemisphere).
Types of compass
A thumb compass is easier to use in combination with a map as it is strapped around the thumb while holding the map in the same hand.
The thumb compass is designed to fit naturally on the hand and thumb and maintain contact with the map.
Thumb compasses come in left-handed versions (for right-handers) and right-handed versions (for left-handers), with wide or narrow needles. They also feature different designs and features – fast or slow needles, with rotating or fixed capsule.
Most right-handed orienteers use the left-handed compass, but some feel it more natural to use the right-handed compass. When someone starts practicing Orientateering it is worth thinking a little about what would work for him.
When purchasing a compass, you also need to purchase one that is balanced for the magnetic zone of your location (northern or southern hemisphere). A compass that works well in Europe and North America will not work properly in Brazil or Australia.
During recent years, the plate compass has lost its popularity and most orienteers have switched to thumb compasses, however, there are those who continue to prefer this type of compass.
The basic functionalities of the baseplate compass are the same as the thumb compass, as it has a needle, usually with red and white markings (or similar), indicating north and south directions.
These compasses usually allow the determination of azimuths in a more precise way. The disadvantage is that they are less practical than the thumb ones.