Behavior of Unusual Ship Forms 



height and exciting moments of this type ship afford a great advantage. It would 

 be no problem, with a relatively simple control system, to activate the main foil 

 flaps or the stern plane to counter these motions. Quite possibly, control by 

 manual adjustments of the control surfaces may only be required as the motion 

 picture records indicate the pitch frequency to be quite low. 



Figures 21 and 22 present the heave response for 1.0 L and 2.0 L regular 

 waves. Beyond doubt, it is seen that the heave characteristics of the Hydrofoil 

 Semi-Submarine are far superior to any of the ships with which it is compared. 

 Since this ship has an extremely small water plane area, its natural frequency 

 in heave relative to the excitation from the wave system would be very near 

 zero (practically that of a submarine). The heave characteristics, therefore, 

 are more dictated by the hydrodynamic forces resulting from the pitch variations 

 of the ship, its change in proximity to the free surface and the effect of the wave 

 system on vertical force and pitching moment induced upon the ship due to its 

 proximity to the surface, as forcing functions. As indicated, through prudent 

 design this ship concept can be made quite stable relative to the hydrodynamic 

 forces and moments on the ship and large heave motions can be avoided. 



FOLLOWING SEA 



OVERTAKING SEA 

 SHIP SPEED (KNOTS) 



Fig. 22 - Heaving motion in regular 2.0 L waves 

 741 



