In use, the feeder is placed on the beach so that the seaward edge 

 of the bottom of the cylindrical body is 1 or 2 inches above the inter- 

 section of the still water line and the beach. The feeder can be leveled 

 and adjusted to the proper height with the adjustable legs (in this case, 

 the screw assembly from a single post automobile bumper Jack). The supply 

 pipe or hose (see Pigure 2a) through which the sand-water slurry is carried 

 into the feeder goes into the open top of the feeder and discharges about 

 1 foot below the top of the feeder. The water overflow hose is arranged 

 to dispose of the overflow water at some point away from the feeder beach. 



To start the feeder, about 1 foot of dry sand is placed in the feeder 

 body. Then a sand-water slurry is pumped into the feeder from the measur- 

 ing facility with an eductor*. The sand will settle into the bottom of the 

 feeder and the clear water will flow over the top and away from the feeder 

 through the overflow hose. 



When the feeder has been filled to within about a foot of the top, 

 waves are started in the study area and they take sand from a cone-shaped 

 pile that slumps from the bottom of the feeder and move it along the beach. 

 As the sand is removed from the bottom of the feeder, more sand slides down 

 to the body of the feeder to replace the loss and a continuous feeding 

 operation is provided when the sand-water slurry is pumped in continuously 

 during a test. 



The feeding rate is essentially self-adjusting because the rate of 

 feeding is a function of the distance from the bottom of the feeder to the 

 general surface of the sand beach. Thus (see Pigure 3) if the height of 

 the feeder bottom above the beach is large, a large amount of sand is fed - 

 or if the bottom of the feeder is buried, no sand is fed. Pigure 3a repre- 

 sents an eroded condition of the beach which requires a large feeding rate. 

 Under such conditions, with a sizable distance between the bottom of the 

 feeder and the beach, a large feeding rate is provided by the feeder. 

 Pigure 3b represents an approximately normal condition of the beach profile 

 requiring a normal feeding rate. If the feeder should oversupply the beach, 

 the condition shown in Pigure 3c results and the sand supply is cut off. 

 Thus the location of the beach profile is held essentially constant by the 

 feeder. 



In recent tests, a feeder the size of the one shown in Figure 2 has 

 supplied as little as 2,000 pounds and as much as 15,000 pounds of sand 

 per hour. Presumably, it could supply any lesser rate required; however, 

 a smaller feeder may give better results for very small rates - say less 

 than 100 pounds per hour. Por rates larger than 15,000 pounds per hour, 

 a larger feeder or two feeders would probably give better results than a 

 single feeder of the size shown. 



* See Savage, R. P. "Laboratory Study of the Effect of Groins on the 

 Rate of Littoral Transport: Equipment Development and Initial Tests", 

 Tech. Memo, No, 114, Beach Erosion Board, June 1959. 



