Groynes are built to stabilize a stretch of natural or artificially nourished beach against erosion that is due primarily to a net longshore loss of beach material. Groynes function only when longshore transport is present. Groynes are narrow structures, usually straight and perpendicular to the pre-project shoreline. The effect of a single groyne is accretion of beach material on the updrift side and erosion on the downdrift side; both effects extend some distance from the structure. Consequently, a groyne system (series of groynes) results in a saw-tooth-shaped shoreline within the groyne field and a differential in beach level on either side of the groynes.   

Terminal groyne at Sg Ranca-ranca, Wilayah Persekutuan  Labuan