While assessing the breakwater stability through a 3D physical model, the normal practice is to modify the structure element if the breakwater is unstable. However, casting a large number of different sizes of concrete armour is time-consuming and costly. This study assessed the utilization of the constructed model with 6.5T(1:41.37) to represent the 10.0T(1:47.82) and 12.5T(1:51.51) tetrapod(TTP) armours by using 88g TTP units in the model. Only the stability of the main armour at the roundhead was considered and the same structure freeboard in the prototype was considered for new scales. Since the measured Hs at the breakwater include wave reflection from the structure wave condition at the paddles was considered while selecting the input signals for the new scales and selected inputs were verified with the post-calibration. Originally proposed 6.5T units were replaced by the hydraulically stable 12.5T units at the roundhead based on the model results.
