(h) Rubble Mound Stability 



Large-scale (7.5 to 1) tests on stability of rubble mound 

 structures under wave action are being made to spot-check results of 

 the test program at the Waterways Experiment Station in Vicksburg, 

 Mississippi. These tests are being made on a 1 on if slope rubble 

 breakwater constructed of a sand core with appropriate filter blankets 

 covered with several layers of approximately 1-foot diameter, 160- 

 pound stone. Tests have been completed with four waves to determine 

 the design wave height (i.e., that height of wave which will just 

 initiate damage after l| hours of wave attack) for four different wave 

 periods. Although exact analysis has not yet been completed, the 

 design heights for all periods generally seem to be between about 3 

 and 3,5 feet. A single test with a wave approximately 1.5 times the 

 design height has been run to check the rate and amount of damage 

 caused by waves higher than design. 



(i) Wave Measurements and Analysis 



Wave records continued to be taken at five ocean gages (Atlantic 

 City, New Jersey; Palm Beach and Naples, Florida; Huntington Beach 

 and Port Huenerae, California). A development model of a wave spectrum 

 analyzer utilizing magnetic tape records and a spinning tape head has 

 been constructed, and is presently undergoing tests. A magnetic tape 

 recorder was installed on the wave gage at Atlantic City, New Jersey, 

 and is recording continuous data; sample analyses of the first of 

 these tapes are being made with the analyzer. Construction of the 

 step-resistance gage has been improved by replacing the neoprene 

 filling previously used in an aluminum channel by a gage composed 

 completely of plastic. Antifouling paint used with this plastic 

 gage at Atlantic City has worked well during the winter months, and 

 is now being tested during the summer season. Three months test of 

 paint at Naples, Florida shows excellent results also. Three years 

 of visual surf observations made at twenty-seven Coast Guard stations 

 along the United States coasts were summarized and published as 

 Technical Memorandum No. 108. This report also includes some obser- 

 vations of hurricane waves on the Atlantic coast. 



( j ) Regional Studies 



Compilation of data on littoral materials for the south shore of 

 Long Island was continued, as was preparation of a report; compilation 

 of data for the coastal sector from Cape Henlopen to Cape Charles is 

 also under way. 



(k) Technical Report No. 4 "Shore Protection planning and Design" 



A continuing study is being made to improve and supplement present 

 chapters of this publication. The first printing of this publication 

 is now out of print; however, a revised edition has been drafted, and 



41 



