Joosen 



Fig. 4 - Peak resistance values 

 as a function of Froude nunnber 



0.2 025 0.3 



The theoretical result is in agreement with experimental data in the range 

 where the wavelength has the same order of magnitude as the ship length. For 

 shorter waves the diffraction effect is not negligible. 



Ships which are moving forward at constant speed have a peak of added re- 

 sistance in the neighbourhood of A./L = l . Using the frequency of encounter, the 

 theory gives very useful results in this range. 



From the theoretical calculations it can be concluded that the added resist- 

 ance decreases with increasing block coefficient. This cannot be verified by the 

 available experimental data. 



Further experiments are necessary 

 larger block coefficients. 



to check the theory especially for 



REFERENCES 



1. Havelock, T.H., "The Drifting Force on a Ship Among Waves," Phil. Mag. 

 33 (1942) 



2. Hanaoka, T., "Non Uniform Wave Resistance," J. Zosen Kiokai 94 (1954) 



3. Maruo, H., "The Drift of a Body Floating on Waves," J. Ship Res. (1960) 



4. Newman, J.N., "The Drift Force and Moment on Ships in Waves," David 

 Taylor Model Basin Report, 1965 



5. Joosen, W.P.A., "Oscillating Slender Ships at Forward Speed," Thesis, 

 Delft, 1965 



6. Jones, D.S., and Kline, M., "Asymptotic Expansion of Multiple Integrals 

 and the Method of Stationary Phase," J. Math. Phys. (1958) 



7. Tasai, F., "On the Damping Force and Added Mass of Ships Heaving and 

 Pitching," J. Zosen Kiokai (1959) 



646 



