The Map Reading Company Unveils New Inductive-Damped Compass

Innovation in Compass Technology

During elementary school years, many of us constructed a simple compass using a magnetized needle floating on a cork in a glass of water. The water allows the needle to rotate freely and minimizes its tendency to oscillate between north and south. Liquid-filled compasses operate on the same principle; however, even well-manufactured ones can develop bubbles when exposed to variations in temperature or pressure.

The Map Reading Company has designed a new, liquid-free compass employing an inductive damping system. Creating a compass that stabilizes quickly is a challenge, even with a strong magnet, due to the Earth's weak magnetic field. This causes compasses to oscillate and navigate uncertainly around the final orientation for an extended period.

Most compasses use liquid to reduce these oscillations, but a few, particularly military ones, use a conductive support. As the magnet moves, it induces eddy currents in the base plate, generating a weak magnetic field that opposes movement, thus slowing it down. Inductive damped compasses do not develop bubbles; however, they do not allow for map visualization through the base plate. The Map Reading Company resolved this issue by creating a transparent base plate and surrounding the needle with a high-conductivity copper alloy ring. This has led to the creation of a clear-base compass, ideal for map reading that will never develop bubbles.

This is a simple yet innovative design. In fact, The Map Reading Company plans to make most of the project public, allowing anyone to build this type of compass. If you are interested in compasses, we recommend checking out the Earth Inductor Compass.