Sluice Box Rippl To the Editor A- Bolts of the width of sluice for holding tho ripples together The hoop-iron is 1 189 in by 189 in... Know More. Dredge Adjustments. recovery of valu If the sluice does not have enough angle the sluice box will load up causing the riffle openings to The material to be run is usually passed through a classifier before putting it in the sluice. The type, size, shape, angle and spacing of the riffles depend on the usage and manufacturer. There has been some research into riffle design, for instance An Analysis of Sluicebox Riffle Performance, 1990 by R. Clarkson, P. Eng.