Wave-dissipating blocks are crucial to protect coastal areas by dissipating wave energy. The installation of these blocks is traditionally performed by skilled workers based on their experience, making it a challenging task for inexperienced workers. To address this issue, a block installation simulator is developed using Unity 3D, a game development engine. One notable feature of the simulator is its ability to allow users to view the 3D model of the breakwater and the tolerance area. This feature enables users to ensure that the blocks are installed within the designated area of the breakwater, a task that is difficult to achieve on-site. In this paper, we validate whether the display of the trapezoidal prism in the simulator helps improve the accuracy of workers in placing wave-dissipating blocks. Two professionals in the field were tasked with placing all the required blocks within the breakwaters with three scenarios. The results were evaluated based on the porosity of the placements, the number of protruding blocks, and the time consumed to complete the task.