In this research, the efficiency of a breakwater of caissons supported on piles was studied, as well as erosion around the piles under regular waves. The breakwater's hydrodynamic performance was studied by calculating wave reflection, transmission, energy dissipation, and scour. Many variables have been studied such as the change in the draft (D/h) in addition to the change in wave height (h/L). The transmission coefficient (kt) decreases as the relative wave-lengths increase (h/L) and decrease with an increasing relative draft (D/h). The reflection coefficient (kr) has the opposite trend, according to the results. The maximum depth of relative seaward erosion (Dsmax/h) ranged between 0.04 and 0.08 when (D1/h) was changed in the range (0.2-0.6). Empirical equations were developed for estimating the transmission and reflection coefficients. These equations’ results were compared to other experimental and theoretical results and were found to be in reasonable agreement. When compared to other breakwater systems, the suggested breakwater type proved efficient.

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