bulkhead was controlled by a series of gears that allowed generation of 

 specific, discrete wave periods. Later, a variable speed 810-hp motor was 

 installed such that, with one change of gears, a continuous range of wave 

 periods between 2.6 and 24.8 sec could be generated. The maximum operational 

 wave height was approximately 6 ft, although breaking wave heights up to 10 ft 

 were recorded in the logbooks from the movable-bed experiments. Water 

 spillage over the tank walls occasionally occurred. 



Experiment Procedure 



13. The general procedure followed during the movable-bed experiments 

 performed during 1956-1957 and 1962 is described in this section. 



14. Prior to the start of most new cases, sand was emplaced to form a 

 1 on 15 slope. About 1,700 cu yd of sand were required. A fine quartz sand 

 of median diameter 0.22 mm was used in the experiment performed during 



1956- 1957, and a medium quartz sand of 0.40 mm median diameter was used in the 

 experiment performed in 1962. Specific gravity of the sands was 2.65. 



15. The initial beach slope was formed with a small bulldozer. A line 

 was drawn on the side of the tank to direct the height of the bulldozer blade 

 while grading the slope. No sand was allowed to remain on the bottom of the 

 tank seaward of the toe of the beach after formation of the initial slope. 

 The distance between the initial location of the toe of the beach and the wave 

 generator bulkhead was approximately 315 ft for experiments with 0.22-mm sand 

 and approximately 72 ft for experiments with 0.40-mm sand. The effective 

 length of the tank was shortened for the experiment series utilizing 0.40-mm 

 sand because another model had been installed at the end opposite the wave 

 generator, and it was desired not to remove this model. 



Depth surveys 



16. Considerable effort was devoted to development of a profile rod 

 that would give an accurate depth measurement and not sink into the bed. A 

 rod with a pivoting foot produced the best results. Various sizes of feet 

 were employed in a series of refinements of the survey rod. In making the 

 profile surveys it was noted that the porosity of the sand bed differed 

 slightly depending on location along the profile. Near the shoreline the sand 



* Endnotes section appears at the end of the main text. 



13 



