indication is masked within the general scatter of data for both types. 
Results have been given limited distribution by the Board in an interim 
report, "Interim Report on Interlocking Precast Concrete Block Seawall 
Study", by R. A. Jachowski and J. R. Byerly, May 1963. Later formal 
publication is planned, 
(c) Study of Sand Bypassing Operations, 
Efforts were continued to collect all available data on sand by- 
Passing operations (past, present, or planned) for correlation and study. 
Analysis continued of the hydrographic survey data obtained in the Port 
Hueneme area in June 1959, and comparison of this data with previous sur- 
vey data. Coordination with Palm Beach County officials was continued 
for compiling data information on the operation of the sand transfer plant 
at Lake Worth Inlet, Florida. A field observation program was continued 
in the vicinity of Ventura County Harbor, California, in which an offshore 
breakwater (parallel to the shore) forms a protected area serving as a 
sand trap. Use of 3 wave gages at this location, each with different de- 
grees of sheltering, permits some degree of evaluation of wave direction. 
A summary report was initiated which will summarize pertinent details of 
all operations of sand bypassing at coastal inlets in the United States. 
Award of contract was made to install in the Beach Erosion Board 
Laboratory a mass flow density meter using a radioactive source to measure 
flow of sand through a 3-inch pipe. Delivery of the component parts is 
being made separately, and some of these are considerably delayed. Com- 
plete installation of the gage is expected sometime in August 1963, at 
which time it will be tested for acceptance. 
(d) Laboratory Study on Relation of Littoral Drift Rate to 
Incident Waves. 
Yearly summaries of the littoral transport tests for 1961 and 1962 
were prepared. These summaries are in draft form, but are planned for 
limited distribution about the end of the calendar year. 
Considerable effort was expended in attempts to secure a more ade- 
quate measurement of littoral current velocities, and the variations 
thereof. A sonic current meter developed by Westinghouse has shown con- 
siderable promise, but still appears to have certain drawbacks. In the 
meantime estimates of current velocities by dye tracers are being 
continued, 
Testing was continued on determination of the relationship between 
incident wave characteristics and the amount of littoral transport. 
Measurement and analysis of waves has continued in an attempt to determine 
the cause of apparent resonance phenomena in the model basin, and the 
meaning of these phenomena. Of particular concern is the fact that this 
phenomenon results in a change in wave characteristics, not only with time- 
duration in a particular test run, but also for the same time-durations of 
otherwise identical test runs. Some of the effect is caused by inconsistency 
7\ 
