The bathythermograph, or BT, is a small torpedo-shaped device that holds a temperature sensor and a transducer to detect changes in hydrostatic pressure. Lowered into the water from an under way ship, the BT records pressure and temperature changes as it is dropped through the water. Because the pressure is a function of depth (see Pascal's law), it can be correlated with temperature.Fact|date=August 2007 The bathythermograph was first developed by Athelstan Spilhaus.

World War II use on U.S. submarines

Since water temperature may vary by layer and may affect sonar by producing inaccurate location results, bathothermographs (U.S. World War II spelling) were installed on the outer hulls of U.S. submarines during World War II.

By monitoring variances, or lack of variances, in underwater temperature or pressure layers, while submerged, the submarine commander could adjust and compensate for temperature layers that could affect sonar accuracy. This was especially important when firing torpedoes at a target based strictly on a sonar fix.

More importantly, when the submarine was under attack by a surface vessel using sonar, the information from the bathothermograph allowed the submarine commander to seek thermoclines, which are colder layers of water, that would distort the pinging from the surface vessel's sonar, allowing the submarine under attack to "disguise" its actual position and to escape depth charge damage and eventually to escape from the surface vessel.


*cite book
last = Blair, Jr.
first = Clay
authorlink =
coauthors =
year = 2001
chapter = (page 458)
title = Silent Victory, the U.S. Submarine war against Japan
publisher = Naval Institute Press
location = Annapolis, Maryland
id = ISBN 1-55750-217-X

ee also

* Expendable bathythermograph

External links

* A [ bathythermograph] , displayed by Jerome Namias

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Look at other dictionaries:

  • bathythermograph — [bath΄ə thʉr′mə graf΄] n. [ BATHY + THERMOGRAPH] a device for measuring the temperature of the ocean at any specific depth down to c. 1,800 m ( c. 5,900 ft) …   English World dictionary

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  • Bathythermograph — termobatigrafas statusas T sritis Standartizacija ir metrologija apibrėžtis Įtaisas vandens temperatūrai įvairiame gylyje matuoti ir užrašyti. atitikmenys: angl. bathythermograph vok. Bathythermograph, m rus. батитермограф, m; термобатиграф, m… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • bathythermograph — batitermografas statusas T sritis ekologija ir aplinkotyra apibrėžtis Giliavandenis savirašis temperatūros matavimo prietaisas. atitikmenys: angl. bathythermograph vok. Bathythermograf, m rus. батитермограф, m …   Ekologijos terminų aiškinamasis žodynas

  • bathythermograph — noun Date: 1938 an instrument designed to record water temperature as a function of depth …   New Collegiate Dictionary

  • bathythermograph — /bath euh therr meuh graf , grahf /, n. Oceanog. an instrument that makes a record of the temperature at various depths in the ocean. [1935 40; BATHY + THERMOGRAPH] * * * ▪ instrument       any of various oceanographic devices containing… …   Universalium

  • bathythermograph — noun A small torpedo shaped device that holds a temperature sensor and a transducer to detect changes in hydrostatic pressure …   Wiktionary

  • bathythermograph — instrument for recording water temperature as compared to depth Scientific Instruments …   Phrontistery dictionary

  • bathythermograph — bathy·thermograph …   English syllables

  • bathythermograph —   n. instrument visually recording the ocean temperature at various depths …   Dictionary of difficult words

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