Evaluation of Motions of Marine Craft in Irregular Seas 



TIME, SECONDS 



TIME (CONTINUED), SECONDS 



KEY: 



OBSERVED TIME HISTORY OF WAVE AND RESPONSES — 

 POINTS PREDICTED FROM SURFACE WAVE TIME HISTORY 



Fig. 6 - Deterministic prediction of roll and heave response 

 for submerged body in irregular beam seas 



with experimental values in Fig, 6. It is seen that there is excellent agreement 

 between computed and measured values of heave. Also included in Fig. 6 is the 

 time history of the irregular surface wave profile. 



Predicted Roll Time Histories 



As shown in Ref. 5, the roll motions of a submerged body in regular beam 

 seas are derivable from the equations of motion of a damped, linear, single de- 

 gree of freedom oscillating system and are expressed by the following equation: 



483 



