and the tank side wall at the generator end of the flume. A 3/8- inch 

 diameter cable was wound several times around the winch and passed through 

 a sheave that was connected to a turnbuckle which was, in turn, attached 

 to the shoreward wall, and made continuous by fastening the ends together 

 with U-clamps (see Figures 4-a and 4-b). This system allowed the device to 

 be moved back and forth about half the length of the flume, limited only by 

 the inability of the U-clamps to pass either through the sheave or around 

 the winch. The device was then connected to the overhead winching cables by 

 smaller cables attached to the vertical flap valve supporting members on each 

 side of the device above and below the flotation pads. This configuration 

 allowed the device to be moved by the wave action in a dominantly vertical 

 direction unhindered, but restricted to a very small amount of its horizontal 

 motion, back and forth in the flume in the direction of wave motion; the 

 flume walls, of course, eliminated any lateral motion. 



6. Establishment of Equilibrium Profile 



Before testing for each wave condition, the slope was brought to an 

 equilibrium profile using the waves to be tested. First, the water level, 

 measured near the generator blade over the concrete tank bottom well away 

 from the flume, was set at 2.0 feet using a stationary point gage. The model 

 period for the waves to be generated was established using the vari-drive of 

 the eccentrically driven pusher-blade type wave generator. The desired wave 

 height was then established by trial and error by setting the eccentric arms 

 that controlled the amount of horizontal movement of the generator blade. 

 The generator was then started, and the resultant wave heights were measured 

 with a two-wire resistance type wave gage located in 2.0 feet of water just 

 outside the mouth of the flume. By this process, the desired wave height was 

 obtained and waves were allowed to impinge on the coal slope until it was 

 estimated the near-equilibrium had been established over that section of the 

 profile on which the device was to operate. The equilibrium profile for the 

 initial wave condition tested was always established by about 40 hours (about 

 155 prototype hours) of wave action. Whether or not a profile had reached 

 equilibrium was determined by periodic soundings every 0.5 feet along the 

 flume. The soundings were then reduced to a datum and plotted graphically 

 against the profile from the preceding survey. Figure 5 on page 34 shows 

 the equilibrium profile for the initial wave condition for Run I compared 

 with the molded slope before any wave action. 



I I I TEST PROCEDURE 



I . Test Types 



The actual testing procedure began after the equilibrium profile 

 was established. Two basic types of tests were conducted. In the first 

 type, a static test, the device remained at a single location in the flume 

 for the duration of the test. In the second type, a mobile test, the device 

 was moved a prescribed distance by a winch and cable after a certain amount 

 of wave action, usually more than one hour in the prototype (about 20 minutes 

 in the model ) . 



