Modeling Moored Ship Response to a Passing Ship

As a ship passes through a confined waterway long period drawdown and associated diffracted waves are produced that will cause nearby moored ships to experience a transient forcing, imposing moments and tensions on the mooring lines. These passing vessel effects can be significant and are highly complex, depending on the characteristics of the mooring arrangement, moored vessels, the waterway geometry, and the passing ship. Assessing the forces induced and the associated structure loads requires understanding of both the drawdown wave and the dynamic behavior of the moored vessel's response. This paper discusses these issues and presents recent studies involving modeling of passing tanker waves and induced forces on moored vessels within berths dredged along the side of a confined navigation channel. Numerical simulations of the passing tanker at varying speeds and the dynamic mooring response of various sized Liquefied Natural Gas (LNG) carriers at berth were examined. These numerical model simulations were complimented by physical model testing and field measurements of several passing tanker waves in the waterway immediately downstream of the terminal site. These measurements will be compared to the numerical modeling results and the influence of the passing ship on the moored vessel and mooring response will be discussed.