INTRODUCTION 



The submarine, USS REDFIN (SS-272), was utilized as a working platform by the 

 Submarine Systems Section, U, S, Navy Hydrographic Office, to obtain digital re- 

 cordings of surface wave motion and analog recordings of ship and fluid motions. This 

 report is concerned with the spectral analysis of these recordings made while the 

 REDFIN was hovering. 



One of the objectives of the Submarine Systems Section is to collect and analyze 

 data needed to study environmental effects on submarine motion, and the characteristics 

 of the relative water motion in the proximity of the submarine. Such data, recorded 

 while the submarine was hovering or underway at the lowest possible speed, have been 

 analyzed by computing power spectra of the recordings. 



Data presented in this report include composite graphs of spectra of surface wave 

 motion (computed by digital estimation formulae), spectra of the submarine's roll angle, 

 and spectra of the transverse and logitudinal relative flow velocity of water across the 

 submarine's deck (obtained by an analog computer). Examples of spectra of In situ 

 pressure fluctuations, estimated by both digital and analog methods, are presented. 

 Differences in approach embodied in the digital versus analog method of power spectra 

 estimation are discussed, and specific examples are presented to illustrate points of 

 technique required for comparable resolution and statistical stability. Finally, spectra 

 data presented in this report are summarized by presenting mean values of motion in 

 tabular form . 



The objective of this particular test was to study environmental effects on the 

 motion of the submarine. During this test period, wave conditions were generally mild 

 with the result that some data were recorded near the sensitivities of the instruments. 

 Thus, energy spectra and related statistical parameters are representative of conditions 

 encountered under lower sea states . 



This report includes most of the data recorded on REDFIN Cruise IS during the 

 period 28 October to 5 November 1959. During this time, the REDFIN was hovering 

 at a keel depth of TOO feet, and operating in an area centered about 180 miles east of 

 Wilmington, North Carolina. 



Hydrographic Office personnel participating in this test were Messrs. Q. H. 

 Carlson (Senior Oceanographer), A. G. AlexSou, and D. E. Tidrick. 



