Composite vertical breakwaters are structures often used to protect port basins, especially in deep-water conditions. One of the technical solution to optimize the performance of these structures consists in placing the crown wall at a retreated position, aiming at inducing a time lag between the loads acting on the trunk and on the crown wall. In the literature there is a lack of guidelines to consider the effects of crown wall retreat in terms of wave actions and hydraulic performance of the structure. Recently, Romano & Bellotti (2023), based on physical model experiments, provided a first experimental insight on the increase/reduction of the wave loads acting on deep water vertical breakwaters with retreated crown wall placed. The paper presents a physical model study of wave induced forces on a composite vertical breakwater, where the crown wave wall is retreated with respect to the front face of the caisson.
