by two laterally located horizontal beams. The waterline of the device, 

 in fresh water, lay along the center of these rigid beams. Suspended out- 

 side these beams and pivoting on the connecting rod to them, was a pair of 

 rigid vertical members, between which were held four fiberglass flaps acting 

 as check valves, with lead sheathing on their lower edges to speed their 

 closing (see Figure 1-a), With this configuration, the device could be 

 operated only in a constant water depth sufficient to utilize all 4 flaps. 

 The configuration was modified by narrowing the flap valves and placing 

 their supporting vertical beams inside the horizontal beams that connected 

 the flotation pads. In this way, the apparatus could be either raised or 

 lowered by moving the rod from a particular flap valve and replacing it 

 through a lower, or higher, valve as desired. Hence the dredge could be 

 operative and in various water depths (in shallower water than before its 

 mod i float ion) . 



3. Operation of Sand-Moving Device 



Theoretically, the sequence of operation of the sand-moving device 

 is as follows. The device was initially floated over the shoreface seaward 

 of the breakers. Then a wave crest passed, causing the submerged valves to 

 open landward (Figure 1-a), allowing the orbital current to pass through them 

 unobstructed, except for the energy required to open the valves. With the 

 passage of the subsequent trough, a seaward directed current is generated. 

 This current closes the valves and creates a very powerful current downward 

 and seaward, under the device (see Figure l-b). This current causes con- 

 siderable scour beneath the device if it is located a relatively short dis- 

 tance above the surface of the bottom. This scouring action places large 

 amounts of sediment in suspension on the seaward side of the device. The 

 presumption then was that with the passage of the next wave crest, the 

 suspended sediment would be flushed through the opened valves and deposited 

 on the' landward side. Thus material is removed from under the dredge, placed 

 in suspension to seaward, and carried shoreward and deposited by the shore- 

 ward component of the orbital current. By moving the device slowly shoreward, 

 the mound of deposited material ahead of it would be progressively transported 

 i nshore. 



TEST SETUP 



The Wave Tank 



The test series took place in a wave tank which measures 85 feet in 

 length, 14 feet in width, and 4 feet in depth, and has a series of trans- 

 parent glass panels, spaced about 10 feet apart along one side, and an 

 eccentrically driven pusher-blade type of wave generator at one end. This 

 tank was modified somewhat for the testing of the wave-powered sand-moving 

 device. The modification consisted of the construction of a narrow flume 

 along a portion of the windowed tank wall. The narrow flume was necessary 

 to fit the size of the model device so that the waves would not act around 

 it, and to minimize the needed amount of the sand simulant which was fine 

 coal. In addition, the narrowness of the flume allowed the remainder of 

 the shoreward end of the tank to be used as an absorber beach to eliminate 



