摘要:Bantan Coast in Bengkalis Island that suffered worst abrasion due to wave attack. Protection of abrasion area against the wave can be done by proper lay-out of breakwater with certain configuration. To get the optimal configuration of breakwater, wave pattern around the breakwater were analyzed quantitatively. It was conducted to obtain the optimum condition of wave height reduction produced. Evaluation of breakwater lay-out effect to wave pattern can be done by numerical model approached. Wave pattern simulation that occurred due to the breakwater was done by Surface water Modelling System (SMS) - CGWAVE software module. This module is a 2-D depth average numerical model using finite element model. To get accurate simulation, a deviation of the numerical result and the measurement result at several locations was used as the indicator parameter in the calibration process. The results showed that from the result of calibration process was used 1.3 meters wave height and 5.4 seconds wave period. Three breakwaters 20 meters slit configuration produced a maximum value of wave height reduction and wave velocity reduction (in comparison wave simulation without breakwater). This configuration produces 60% height reduction and 14% velocity reduction.