USS Bowfin - Target Bearing Transmitter

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Target Bearing Transmitter
USS Bowfin (SS-287)
TBT

The target designation system is used for the purpose of transmitting and indicating the bearing of the target from the bridge or radar to the torpedo data computer (TDC) and the two plotting stations. It is a simple selsyn-operated system using manually operated bearing transmitters on the bridge and an automatic transmitter coupled to the train mechanism of the radar.

Target Bearing Transmitter: This instrument consists of 2 permanently mounted peloruses on the bridge. One is located at each end of the bridge. Each pelorus has a pair of watertight and pressure-proof binoculars of the high light transmission type. An illuminating system is built into them to make the cross wires visible when the instrument is used at night. The pelorus can be rotated through 360 degrees in azimuth and is equipped with a scale so that the operator may read the bearing at which the instrument is set. A selsyn generator inside the pressure-proof case of the instrument transmits the bearing of the target when the pelorus is pointed at it. The hand contactor for the buzzer system is built into one of the training handles.

From: Submarine Electrical Installations, NAVPERS 16162, June 1946

During Bowfin's second war patrol, ENS John Bertrand manned the TBT on the aft end of the bridge, an open and extremely exposed position. The following paragraph is taken from the war patrol report, written by Commanding Officer Walter T. Griffith, CDR, USN:

"I wish to cite particularly the performance of duty by Ensign J. R. Bertrand, USNR, who manned the TBT for surface attacks. On the morning of 28 November (1943) while under close enemy fire at 500 yards, and after a shell had hit within 20 feet of him, he calmly manned his station and continued to transmit bearings which resulted in sinking the large vessel firing at us."

For his bravery under enemy fire, ENS Bertrand was awarded the Silver Star.

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