SEMISUBMERGED SHIPS FOR HIGH-SPEED 
OPERATION IN ROUGH SEAS 
Edward V. Lewis and John P. Breslin 
Davidson Laboratory 
Stevens Institute of Technology 
Hoboken, New Jersey 
To evaluate methods to obtain high speed at sea without large in- 
creases in ship size, several hull configurations were surveyed; in par- 
ticular semisubmerged craft designed to operate at or just below the sur- 
face. By increasing judiciously the amount of submerged hull-volume, 
both high-speed resistance and pitching motions in rough seas can be 
reduced. 
The hull configurations that were surveyed included a craft that resem- 
bles a surfaced submarine, a slender ship with large bow and stern 
bulbs, and a craft (semisubmerged) that is similar to a shallow-running 
submarine with a permanent surface-piercing strut for air supply and ex- 
haust. The semisubmarine, potentially, can exceed submarine speeds 
because of its low resistance and good sea performance. In addition, the 
air-breathing power plant of the semisubmarine weighs less and requires 
less space than a nuclear power plant. 
The study of the calm-water stability characteristics of the semisub- 
marine at intermediate and extreme speeds shows that depth and direc- 
‘tional stabilization can be achieved with tail fins of reasonable size, 
except at low and intermediate speeds, where stabilization by fin area 
alone is not attractive; however, active controls readily can provide op- 
eration at constant depth in calm water. Analog computer studies show 
a peculiar dependence upon the distribution of stabilizing surfaces and 
other parameters. Therefore, precise and extensive model tests are re- 
quired to explore the near-surface dynamics of this craft to fully develop 
its advantages. 
INTRODUCTION 
The successful development of the true submarine has resulted in a craft that can re- 
main submerged almost indefinitely and operate at high speeds in a three-dimensional realm 
of steadily increasing depth. When a submarine runs far below the surface, surface wave- 
making resistance is virtually eliminated; the remaining resistance is caused almost entirely 
by skin friction. Although a submarine can be made squat in comparison with a surface ship 
to minimize the ratio of wetted surface to volume, its surface area is greater than that of a 
comparable surface ship. This is a disadvantage at moderate speeds; however, at high 
speeds, this disadvantage is more than compensated for by the elimination of surface wave- 
making. Power is directly proportional to speed cubed, even at high speed; therefore, speed 
is limited only by the weight and size of the power plant. 
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