Model Studies of Apra Harbor, Guam, M. I. Progress Report for May, 1948

Tests of three different inner breakwaters to protect the repair basin and inner harbor from waves entering through the existing harbor entrance were run this month. Two were located on Jade and Southern Shoals and one on Jade, Southern and Western Shoals. The breakwaters on the shoals reduce the disturbances in the areas of primary and secondary usage in the repair basin to less than half those occurring with the shoals alone. Combinations of breakwaters and channel fills between the various shoals supplemented the studies and these results are included as well. Tests were also run to compare the effectiveness in the outer harbor of the alternate entrance through Luminao Reef with that of the existing entrance between Spanish Rocks and Orote Point. The alternate entrance is very effective. In addition to the tests described above, induced current studies were made. Many of these were for the purpose of developing the technique of daytime photography of reflector floats. Because test runs at the end of the month are incomplete and do not comprise a logical unit for presentation, their analysis will appear in next month's report.