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JP Sonar


Close up of JP hydrophone on submarine deck
JP hydrophone pedestal on submarine deck
Both: U.S. Navy via Navsource.org

JP was a hydrophone (passive sonar) set developed by the Underwater Sound Laboratory at New London in 1942. This hydrophone was sensitive to audible sound frequencies between 70 Hz to 12 kHz and took the form of a T-shaped linear hydrophone mounted on the forward deck and operated from the forward torpedo room beneath. The hydrophone had enough directionality for a skilled operator to work out a fairly accurate bearing to target, and the location on top of the deck eliminated the danger of wrecking the hydrophone if the submarine came to rest on the ocean floor (either deliberately to evade attack or accidentally due to poor navigation or inadequate charts.)

JP was ordered installed on all fleet submarines on 22 September 1942 and remained in use until it was superseded by the superior JT set just as the war was ending.

References

Alden (1979)

Friedman (2004)


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