TABLE 1 



Model Particulars 





Model and Type 



1 



2 



3 



4 



5 



Cargo 



Cargo 



Cruiser 



Cruiser 



Destroyer 



Lm 



20.0 



21.86 



20.0 



20.0 



20.47 



L/B 



7.50 



6.95 



9.1S 



9.52 



9.82 



L/U 



18.75 



21.12 



26.30 



29.12 



28.53 



B/H 



2.50 



3.04 



2.86 



3.06 



2.91 



Cu. 



0.706 



0.717 



0.735 



0.738 



0.735 



Ob 



0.600 



0.605 



0.540 



0.523 



0.462 



c. 



0.850 



0.837 



0.764 



0.709 



0.629 



C^B/C^H 



2.08 



2.60 



2.76 



3.19 



3.40 



L/V^/3 



6.16 



6.22 



7.65 



8.10 



8.46 



■^0 



1.86 



1.825 



1.615 



1.555 



1.555 



The body plans for the five models are given in Figures 1 through 5. Models 1 and 2 

 represent two cargo-passenger ships that have closely similar hull characteristics. The major 

 difference is the somewhat smaller draft of Model 2 relative to its beam dimension. The two 

 models have relatively full forms characterized by sections of predominantly U-shape. 



Models 3 and 4 represent two cruiser type hulls that are somewhat finer than the previ- 

 ous two models. They have more V-shape sections, especially aft of midships. Model 5 is 

 still finer in form than Models 3 and 4, and represents a typical destroyer hull. 



An examination of Table 1 and the body plans of Figures 1 through 5 indicates that the 

 various models of this investigation have widely different hull characteristics and coefficients. 

 The only similarity among the models appears to be a water-plane coefficient that varies only 

 between values of 0.71 and 0.74. 



The models chosen for this investigation were restricted to those which were approxi- 

 mately the same length and which were tested in the same towing facility. This was done to 

 insure that differences in motion amplitudes among the various models could be attributed 

 solely to differences in hull characteristics. 



The study of Reference 4 indicates that there are no scale effects on the seakeeping 

 characteristics of a 5-ft and IQ-ft geosims. The extension of these results to 20-ft models 

 is probably warranted. There is considerable evidence, however, to indicate that differences 

 in test facilities and equipment can have a major influence on motion characteristics. ' 

 Until a better correlation is established among the various towing facilities, therefore, the 

 results given in this report can be considered strictly applicable only to 20-ft models 



