TABLE 1 - VALUES OF PRINCIPAL PARAMETERS FOR THREE HULL MODELS* 



Parameter (and Unit) 



Hull Form 



SWATH 6A 



SWATH 6D 



Twin Ellipsoid 



Displacement (long ton) 



2579 



2815 



1.823 



Characteristic length L (m) 



54.3 



73.1 



6.1 



Length of waterline (m) 



52.5 



68.0 



6.096 



Length of main hull (m) 



73.2 



73.2 



6.096 



Beam of each hull at waterline (m) 



2.2 



2.2 



0.762 



Hull spacing between centerline (m) 



22.9 



22.9 



1.143 



Draft at midship (m) 



8.1 



8.1 



0.381 



Maximum diameter of main hull (m) 



4.6 



4.6 



— 



Longitudinal center of gravity 









aft of main hull nose (m) 



35.5 



36.1 



3.048 



Vertical center of gravity (m) 



10.4 



9.1 



0.381 



Longitudinal GM (m) 



6.1 



26.4 



6.096 



Radius of gyration for pitch (m) 



16.9 



19.0 



1.2192 



Waterplane area (m) 



193.9 



211.2 



7.297 



Length of strut (m) 



52.4 



25.8/strut 



— 



Strut gap (m) 



0.0 



16.4 



— 



Maximum strut thickness (m) 



2.2 



3.1 



-- 



*Dimensions are full-scale. 



theory is exact. The added-mass coefficients A.., i = 3, 5, computed with the 

 slender-body theory compare better with the three-dimensional results than with 

 those of the strip theory. This is especially true at low frequencies. At high 

 frequencies the results of the strip theory and the slender-body theory are almost 

 the same, as in Reference 4 in which the kernel functions of Equation (27) vanish. 

 The abrupt changes in the curves of added-mass and damping coefficients are due to 

 the hydrodynamic interaction of the two hulls when the (nondimensional) frequency is 

 approximately 2.5. 



The exciting forces F~ and moments F,- are shown in Figure 5. The slender-body 

 theory predictions for pitch moments F,. are found to be nearly the same as those of 

 the strip theory, but higher than those of the three-dimensional theory. The 



15 



