What Is a Compass Inclinometer?

The inclinometer on a compass can provide the height, in degrees above the horizon line, of any object. Many measurements such as this can be taken with a compass inclinometer to develop a basic topological survey map, to measure range of motion in the joints of a body, or to determine the “look angle” of a satellite antenna toward a satellite. Compass inclinometers measure in degrees rather than percentages, but they come with a conversion tool that converts to percentages for use in individual construction projects when necessary to measure a slope or if you need to measure an angle not easily measured in any other manner. A compass inclinometer can also be used with a tape measure to take readings to produce cave maps below ground, something cave scientists and speleologists do on a regular basis. When above ground, graph paper and a protractor can help produce the cave map from these readings.

An inclinometer is also sometimes called a tilt sensor, as it can measure angular tilt by producing a false horizon. This tilt sensor capability is the same as those in use in flight control systems, auto security systems, and cameras. This same technology is also found in game controllers for popular video game modules and is often used by civil engineers to measure an incline on land that will become a construction site. Calculating the deviation from true vertical or true horizontal or determining latitude using the northern hemisphere’s “Polaris” and the southern hemisphere’s “Crux” is another function on a compass inclinometer.

A compass inclinometer works on the geometry of triangles; some use measurements and others employ percentages and degrees. When looking through the lens of a compass inclinometer, three things are visible: a protractor, a weighted line, and a viewing scope. A person looking through the lens will notice that the weighted line changes place along the protractor as he or she turns his or her head. Standing very still, a person can take the measurements that, when entered into algebraic equations, determine the angle by triangulation. These measurements are the viewer’s distance in feet from the object he or she is viewing, and the height of his or her eyes — generally, 6 inches (15.25 cm) from his or her height.

To calculate from a specific distance, an inclinometers must be calibrated accurately. Users may need to consult their manuals to recalibrate inclinometers. Once calibrated, a compass inclinometer can help safely map hiking trails and measure steep inclines and declines such as ravines, cliff faces, and cracks in a mountainside snow pack.