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APPENDIX 1 

 SPECIFICATIONS FOR AUTOMATIC SHIP'S MOTION RECORDER 



1 . GENERAL DESCRIPTION OF THE INSTRUMENT 



The ship's motion recorder is to record simultaneously, on one chart, 

 the output of three accelerometers as well as the voltage output of 2 other 

 transducers whose output may be proportional to angle of roll, pitch, pressure, 

 strain, etc. All channels shall essentially be alike, but provision shall be 

 made to obtain different over-all sensitivities. 



The operation of the equipment shall be automatic, not requiring 

 servicing for a period of several weeks. The recorder shall be operated auto- 

 matically for 2 minutes every hour or other selected time duration at desired 

 intervals. Transducers are to be energized continuously. A dial-type indi- 

 cator, graduated from to 2 hours, is to be incorporated in the recorder so 

 that, at will, continuous recording within this range can be accomplished by 

 setting a knob on the timer. Another switch, wired in parallel, is to provide 

 manual "on-off" control of the chart drive. The recorder should incorporate 

 suitable attenuators on all channels. 



2 . ACCELEROMETERS 



a . Amplitude Range 



1 Linear Accelerometer + 1 g 



1 Angular Accelerometer + 1 radian/sec 2 



1 Angular Accelerometer + 1/2 radian/sec 2 



b. Frequency Range to 3 cps 



c. Damping About 0.7 of critical damping 



d. Linearity ±30 percent of actual value at 



minimum discernible deflection* 



+ 5 percent of actual value at 

 1/10 full scale 



± 1 percent of actual value at 

 full scale 



e. Temperature range over which equipment will be used is 30° to 110° F. 



f . The temperature stability of the accelerometers is to be such that, 

 if a stream of water at a temperature from 32° to 100° F. is passed over the 

 gage for a period of 10 minutes, there shall be no change in output of the 

 gage in excess of 2 percent of full-scale output. 



•Minimum single amplitude of deflection discernible on the recording chart Is 0.005 inch. 



