Fathometer

Fathometer, pronounced fa THAHM uh tuhr, is an instrument used on ships to measure the depth of the water. It works by sending a sound down through the water to be echoed back from the bottom. Navigators can measure the depth below the ship by measuring the time it takes the sound to return. The speed at which sound travels in water is known. Continuous soundings of this kind can be taken all during a voyage. The fathometer contains two parts, a submarine oscillator, which produces the sound, and a hydrophone echo receiver. The echo is amplified and sent to a depth indicator and a recorder near the bridge. The reliability of a fathometer depends on a number of factors, including the depth, temperature, and saltiness of the water. See also Sonar.

Contributor: Robert F. Beck, Ph.D., Prof. and Chair of Naval Architecture and Marine Engineering, Univ. of Michigan.

Fathometer

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