T.M. No. 97 (Continued) 



of waves of low amp I itude in deep water and a smooth bottom. 

 Coefficients are defined by experiment using an oscillating bed 

 in a laboratory tank. 



T.M. No. 98 - June 1957 



Hurricane Wave Statistics for the Gulf of Mexico by Basi I W. Wi I son 



This report contains the results of a statistical hindcast study 

 of heights and periods of significant waves generated by hurricanes 

 in the Gulf of Mexico in the period 1900 to 1949. Results are pre- 

 sented in a series of polar plots of frequencies of occurrence of 

 waves of given height and period at deep water (100 fathoms) stations 

 offshore in the Gulf of Mexico. This report complements Technical 

 Memoranda Nos. 84 to 89. which presented statistical summaries for 

 all or ordinary wind waves hindcast for the same *stat ions. 



T.M. No. 99 - September 1957 



Model Tests on a Triple-Bulkhead Type of Floating Breakwater 

 by Culbertson W. Ross 



Test procedures and results are summarized for a laboratory 

 model study to test the effectiveness of a particular design of a 

 floating breakwater acted on by several wave trains from different 

 directions and to measure stresses in mooring cables. Tests were 

 performed at a I to 24 linear scale. The efficiency of the break- 

 water in reducing wave heights drops off rapidly with an increase 

 in wave period beyond 8.5 (prototype) seconds or when the wave 

 length approximates the width of the breakwater section from front 

 to back. Forces required to hold the breakwater in place against 

 larger waves (greater than 9 to 1 feet prototype) exceeded 200,000 

 pounds per anchor chain, and prototype stresses in some of the 

 braces and struts exceeded present practical design limits. 



T.M. No. 100 -October 1957 



Wave-Generated Ripples in Nearshore Sands by Douglas L. Inman 



A study of the occurrence of sand ripples generated by wave 

 action in the nearshore area has been made based on observations by 

 swimmers equipped with self-contained underwater breathing apparatus 

 (SCUBA). The wave length, crest length, height and symmetry of the 

 ripples were measured and compared with size of the sand and with 

 orbital displacement and velocity of the wave motion generating the 

 ripples. In general, ripple size increased with sand size and, to 

 a certain extent, with water depth. Ripples in exposed areas were 

 generally larger than those in sheltered bays. Ripples were always 

 present when the orbital velocity was between about 0.3 and 3 feet 

 per second. 



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