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Note: HOOK

Abstract: This paper presents a fast numerical method to analyze heavy-lift operations of ships in short crested waves. For this purpose, a sea-keeping simulation method for the coupled motions of a heavy-lift vessel and a freely suspended load is developed. The method considers the motions of the ship in six degrees-of-freedom and the suspended load as a point mass. The coupling of the multi-rigid-body system of the ship and the suspended load is considered by solving the equation of roll motion together with the Euler-Lagrange equations of the load. This approach allows the simulation of several hours of real time motion in short crested waves within only a few seconds. Consequently, the method is particularly suitable when very long or numerous sea-keeping simulations or statistical results are required. Moreover, the method is applied to evaluate the sea-keeping capabilities of a heavy-lift vessel during a lifting operation conducted offshore in 2013.