HYDRODYNAMIC DESIGN OF AN S 3 

 SEMI-SUBMERGED SHIP 



Thomas G. Lang, PhD 



Naval Undersea Research and Development Center 

 San Diego 3 California U.S.A. 



ABSTRACT 



The S 3 semisubmerged ship concept is described, 

 and hydrodynamic characteristics are presented. Va- 

 riations of the basic form are discussed and results 

 of model tests and theory are presented on static and 

 dynamic stability, drag and power, motion in waves 

 and effectiveness of an automatic control system for 

 motion reduction. The results show that an S is in- 

 herently stable at all speeds, well damped in all mo- 

 des, and should provide a near-level ride in high sea 

 states if equipped with an automatic control system. 

 Furthermore, an S should have less drag than a 

 monohull at the higher design speeds. 



INTRODUCTION 



Military and commercial users of ships are continuously 

 searching for new design concepts which would provide improved 

 speed, range, payload ratio, seaworthiness, or reliability. Such 

 improvements are preferably to be attained at reduced cost, although 

 cost tradeoffs are the general rule. Since monohulls have long been 

 the most widely used hull form, it is generally accepted that their 

 lead position is not easily challenged. 



The large monohulls can carry a very large payload ratio, 

 they have a long range at moderate -to-high ship speeds, and they 

 offer good seaworthiness at a relatively low initial and operating cost 

 per unit of payload. The small monohulls, on the other hand, have 



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