NO. 73 - April 1955 



II_A "Graphical Approach to the Forecasting of Waves in Moving 



Fetches" by Basil W, Wilson 



Development and application of a graphical technique to 

 the determination of maximum significant wave heights 

 and periods attained by waves in moving wind systems 

 are described. Existing Sverdrup-MunkHBretschneider 

 deep water forecasting data are assembled in a single 

 chart over which a space-time wind-field representing 

 any given moving wind system (in relation to a parti- 

 cular point on the coast) can be placed by superposition 

 for the evaluation of the characteristics of the waves 

 generated at any specific point in space and time within 

 the windfield. The method is applicable to both 

 approaching and receding storms and permits of decay 

 aspects being taken into account in the usual way. An 

 example is given of application of the method to fore- 

 casting wave conditions in the path of a hurricane. 



NO. 74 - May 1955 



I_A "Water Surface Roughness and Wind Shear Stress in a 

 F Laboratory Wave Channel" by Osvald Sibul 



Vertical wind velocity profiles were measured in a 

 laboratory wave channel by use of a Pitot tube, simul- 

 taneously with observation of wave heights, periods and 

 water surface slopes. The velocity profiles were analyzed 

 for resistance coefficient, characteristics roughness 

 length, and shear stress exerted by the wind on the water 

 surface. Methods for extending the data to field con- 

 ditions are given. The laboratory results compare 

 favorably with field measurements. It is concluded that 

 snail scale laboratory equipment can be used to study 

 mechanics of energy transfer between wind and water. 



NO. 75 - June 1955 



I^ "Mechanics of Bottom Sediment Movement Due to Wave Action" 

 by Madhav Manohar 



Results are presented from an analytical and experi- 

 mental (laboratory) investigation of the motion of 

 sediment induced by action of surface waves of large 

 length and small amplitude in relatively deep water. 



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