On rough seas, a boat’s rocking can be more than uncomfortable—as “Deadliest Catch” participant Johnathan Hillstrand told the Seattle Times after a close call, “man overboard” is something you never want to hear. “We hear it too much,” Hillstrand said, during a season that had already seen three fishermen perish. In wet weather and white water, stability can be a matter of life and death.
That’s why many vessels now use gyroscopic stabilizing mechanisms.
By themselves, gyroscopes are not a new technology—a sickly Frenchman who failed to become a doctor invented them in the 1850s. Leon Foucault had a short-sighted eye and hated school. “His health was delicate, his character mild,” wrote a childhood friend, “timid and not expansive.” He preferred to play with machines. His mother forced him into medical classes, where he performed better than anyone expected—until he saw his first blood and fainted.
But in 1851, Foucault had the idea he could show the Earth’s rotation. In his basement, he constructed a pendulum that could move in any direction, set it swinging, and watched as it kept to the same plane while the Earth moved beneath it. Scientists were so struck by the discovery that he was asked to repeat the experiment in front of the entire Paris Observatory.
It was a short step from there to the gyroscope, Foucault’s next invention to demonstrate the motion of the Earth. A gyroscope is a spinning wheel, called the rotor, that rotates around an axis. The rotor is mounted between two rings, known as gimbals, that pivot around their own axes. This means that when pressure is exerted on the gimbals, the rotor is unaffected, making it a useful tool to measure compass headings and pitch, roll, or yaw angles—useful for sailors trying to find the horizon on a foggy morning, or in a spacecraft headed to the ISS.
Gyroscopes are still used in many important tools, like the Hubble Space Telescope, racecars, airplanes, and cell phones. (Ever wonder how Pokemon Go’s augmented reality actually works? Your iPhone uses the camera and the phone’s gyroscope to display an image of a Pokemon as though it were in the real world.)
In a boat, the natural rocking of the water moves the spinning gyroscope, producing pressure known as torc. “As the boat rolls, the gyro tilts fore and aft,” says Andrew Semprevivo, Vice President of Sales and Marketing for Seakeeper, the maker of one of these stabilizing gyroscopes. The stabilizers use the energy produced by pushing the spinning gyroscope off its vertical axis to correct the boat’s heel. It’s basically the same principle behind a surfer adjusting his body’s position on his board to match a wave’s surface.