Underwater rubble mound leveling works usually have been carried out as a preliminary process prior to\ud
the installation of caissons and blocks onto the seabed in a harbor and wave energy structures. So far, underwater\ud
construction works are mostly depended on divers. These divers are confronted with many difficulties, such as working\ud
time limitation due to depth, poor visibility in a working field and so on. These problems can be overcome using\ud
machineries in the underwater construction. The practical unmanned underwater equipment for port constructions was\ud
newly developed. The equipment can be applicable in underwater leveling works of rubble mound by using its blade\ud
and bucket with automatic arms. Also, it can monitor the working environment using sonars and optical devices. The\ud
safety analysis considering harsh circumstances such as strong currents is necessary because the equipment is usually\ud
mobilized on the seabed. In this paper, the effect of tidal current forces on the behavior of the equipment was\ud
investigated by using the Computational Fluid Dynamics (CFD), which is mainly used in investigating the relative\ud
movements of fluid and structure. The numerical results reveal that the possibility of overturning and sliding of the\ud
equipment can be negligible and the structural stability can be assured under a given current velocity of 1m/s
