Each individual disc measures 4 inches in diameter and consists of a series of 5 fins projecting from the center hub. Midway on the length of the disc hub is a radially extended web member, which supports an annular-section ring-shaped flange in a co-axial relationship with the central bore. To assist in damping the longitudinal wave forces, the web member is formed with a multiplicity of circular openings. The web in conjunction with the multiple fins combines to impede, aerate, dampen and break up the other. Both the web and the fins functions are very important in that most waves will not intersect the swimming lane in a perpendicular manner.