ABSTRACT 



A model of a wave-powered, sand-moving device, suggested by tlie staff 

 of the U. S. Rubber Company Research Center, was tested for its feasibility 

 as a dredging device early in 1965 at the U. S. Army Coastal Engineering 

 Research Center. Sixteen tests were made under various wave conditions at 

 a 1:15 scale reduction. Waves with prototype periods of 5, 7, 9, and 15 

 seconds were tested. Wave heights varied from I.I to 4.4 prototype feet 

 in prototype offshore depths of 38.7, 34.5, and 30 feet. In half of the 

 16 runs, more sediment was accreted landward of the dredge than was eroded 

 and deposited seaward of it, yet, in only two of these tests was the shore- 

 ward accretion significant. On the other hand, of the eight tests that 

 resulted in erosion on the shoreward side of the device, five showed sig- 

 nificant amounts. Accretion landward occurred when the dredge was operated 

 in shallow water over a nearly horizontal bottom. Over a sloping bottom, 

 the dredge served general ly to erode material and deposit it downslope. 

 These results indicate that the device, at least in its present form, is 

 unsuitable for use In moving sand shoreward from offshore sources, and 

 that further testing in the prototype is not justified. Despite the dis- 

 appointing resu Its, the operation of the device ill ust rates the possi bi I ity 

 of a great potential for the utilization of wave power. 



FOREWORD 



Artificial beaches have proven to be so successful and economical as 

 a means of shore protection that in some localities there is now a scarcity 

 of onshore sources of hydraulic fill. Presently seismic explorations are 

 seeking offshore sources of sand that could be recovered by ocean-going 

 hopper dredges. A device, such as the one tested here, could prove in- 

 valuable in moving sand to the turbulent zone from the limit of deep-draft 

 dredge operation. 



Fredericl< F. Monroe, an Oceanographer in the Research Division, con- 

 ducted the tests and prepared the report under the generaJ supervision of 

 Thornd i ke Saville, Jr., Chief of the Research Division. During the time 

 of the tests. Colonel F. 0. Diercks was Director of the Center, and at the 

 present time, J. M. Caldwell is both Acting Director and Technical Director. 



NOTE: Comments on this publication are Invited. Discussion will be 

 publ ished In the next issue of the CERC Bui letin. 



This report Is published under authority of Public Law 166, 79th 

 Congress, approved July 31, 1945, as supplemented by Public Law 172, 88th 

 Congress, approved November 7, 1963. 



