A tachometer is an instrument designed to measure the rotation speed of a shaft or disk. Tachometers generally measure rotations per minute (RPM) though some models also serve as rate meters and/or totalizers. Measuring the rotational speedof a spinning object is important for a number of reasons.

Pitometer logs (also known as pit logs) are devices used to measure a ship’s speedrelative to the water. They are used on both surface ships and submarines. Data from the pitometer log is usually fed directly into the ship’s navigation system.

Speed Measuring Instruments. Speed measuring instruments vary with the job. Whether measuring traveling speed, wind speed, acceleration or engine speed, there is a proper instrument for calculating that form of speed. Police use RADAR and LIDAR to measure traffic speed.