Behavior of Unusual Ship Forms 



FOLLOWING SEA 



OVERTAKING SEA 



SHIP SPEED (KNOTS) 



AHEAD SEA 



Fig. 19 - Pitching motion in regular 1.0 L waves 



FOLLOWING SEA 



OVERTAKING SEA 



SHIP SPEED (KNOTS) 



AHEAD SEA 



Fig. 20 - Pitching motion in regular 2.0 L, waves 



Figs. 21 and 22 for 1.0 L and 2.0 L waves, respectively. An interesting comment 

 is in order here concerning the nature of the response. As will be noted, the re- 

 sponse data in ahead seas of the other three ships also shown on the figures for 

 comparison, have similar characteristics in that the response reaches a peak 

 under critical conditions and then falls off. However, the response of the Hydro- 

 foil Semi-Submarine contains two peaks instead of one. It was found that for the 

 condition where the ship speed exactly equalled the wave celerity in overtaking 



739 



