Kim and Merciev 



The 6-in and 12-in diameter models were tested at Davidson Labor- 

 atory by Mercier [59J , while the largest model was tested at the 

 Naval Ship Research and Development Center by Gersten [60] . 



The lessons of these test results are not entirely unexpected : 

 sharp-edged geometric details produce high drag and little scale effect 

 while well-rounded geometries produce lesser drag and are susceptible 

 to perceptible scale effect. These results may provide qualitative guid- 

 ance for other applications and configurations, such as for choosing a 

 suitable scale ratio for a wave test of a floating platform with buoyant 

 caisson-and -footing floatation elements. 



Damping effects, while of principal importance for a fairly 

 narrow band of frequencies near resonance, can have an appreciable 

 effect on spectral response when there is appreciable wave energy at 

 the resonant frequency. The nature of the damping and its dependence 

 on geometric and flow features is as yet only imperfectly understood 

 adn needs to be studied more vigorously. 



ISOLATED FLOAT EXPERIMENTS 



An experimental program was undertaken to determine hydro- 

 dynamic forces and moments and certain other features of perform- 

 ance for several floats. The results of these experiments may be used 

 in conjunction with analytical work, such as described in the last sect- 

 ion, to obtain empirically adjusted analytical procedures for perform- 

 ance evaluation. Certain results may also be compared with results of 

 interaction tests, where several floats were placed in close proximity, 

 to determine hydrodynamic interaction. 



Models 



Several types of models were built to evaluate the influence of 

 various features on performance. Some of these models were selected 

 on the basis of the analyses described in the previous section of this 

 report. Some were also tested as part of an array of floats to evaluate 

 interaction effects. The scope of isolated float testing was curtailed 

 when the extent and significance of interaction effects on wave-induced 

 vertical floats was discovered. All models investigated in this test 

 program were built to a scale ratio of 1:57.6. 



Figure 36 illustrates the models which were tested. The deep 

 cylinders (Figures 36-36) were planned to investigate the effect of 



832 



