Navigation devices are tools used to help people find their way from one place to another. Sonar (5 letters) is a device that uses sound waves to detect objects underwater. Sextant (7 letters) is an instrument used to measure the angle between two visible objects, such as the sun and the horizon, to determine a ship's position. Loran (5 letters) is a navigation system that uses radio signals to determine a ship's location. All three of these devices are used to aid in navigation.