Magnetic compasses, also known as needle or pocket compasses, are the most common types of compasses. They identify the direction of the magnetic north using a magnetized iron or any steel set in a low friction. Most models have marked north-end metal pieces, usually in red.
Gyrocompass (also gyro compass)
Gyrocompasses identify the direction of the true north by using a fast spinning ball or wheel. It operates on the law of conservation of angular momentum. Gyro compasses are commonly used on boats.
Astrocompass (also astro compass)
Astrocompasses rely on celestial body positions to determine the true north. They require information such as date, time, and astronomical data to be used accurately.
Solid state compass
Solid state compasses use electromagnetic sensors to determine directions. They calculate the direction the compass is pointing to accurately.
GPS compasses identify the user’s current location and the location he is going to. They use the satellites orbiting the earth in a geo-synchronous manner to determine direction. They are generally reliable and easy to use. They are commonly used by drivers, hikers, and sea travelers.
Baseplate compasses are also called orienteering compasses. They have magnetic needles suspended in clear liquid housed in rotatable protractor bases. Most models are made of Perspex or clear plastic. They are ideal for outdoor activities.
Card compasses are also known as marine compasses. They have fixed needles and moving compass cards suspended in fluid. They are usually easier to read than needle compasses. They are commonly used on boats and cars. They are mounted near the steering device to absorb as much of the vehicle’s motion. Most models are marked to display readings from zero to 360 degrees. The hand held models are commonly used to see the bearings of distant objects in a fixed position.
Thumb compasses are modified baseplate compasses. They are designed to fit exactly around the thumb. They allow the user to hold the map and compass together in one hand. They are commonly used in orienteering and regaining.
Prismatic compasses have glass prism systems and hairlines that line up the objects to be sighted. They have compass cards that rotate and rest, allowing the reading off of the bearings through the prisms. They are sophisticated hand held compasses.