Planing Craft 



long wave components involved. The chairman described some of the results 

 from a systematic series of planing-huU tests in rough water currently under- 

 way at the Davidson Laboratory, Stevens Institute of Technology. The results 

 showed that for speed-length ratios larger than approximately 2, the pitch, 

 heave, accelerations, and added resistance are significantly nonlinear and that 

 these nonlinearities increased with increased speed up to a maximum test 

 speed-length ratio of 6.0. Further, it was found that wavelength had a signifi- 

 cant effect on nonlinear behavior. For wavelengths of the order of hull length, 

 linear relations for motions were observed at all speeds. Deviations from 

 linearity increased as wavelength increased and reached a maximum for wave- 

 lengths approximately three times the hull length. For longer wavelengths, the 

 trend to linearity in motions increased until, at a wavelength approximately five 

 times the hull length, linear motion relations were observed at all speeds. The 

 accelerations and added resistance were strongly nonlinear at all test speeds 

 and wavelengths. These Davidson Laboratory results were obtained from regu- 

 lar wave tests, where, for a given test wavelength, the wave height was varied 

 and from tests in two irregular sea states. 



Dr. Graff of the Ship Model Tank at Duisburg made some general comments 

 on operating regimes for round- and vee-bottom hulls. Quantitative information 

 on this subject must await publication of his work. 



G. Rosen of United Aircraft completed the session with a sound movie on 

 full-scale operation of high-speed planing hulls driven by lightweight gas turbine 

 engines. 



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