On the estimations of ship motions during maneuvering tasks in irregular seas

It is well known that ship dynamics in irregular waves can lead to large amplitude motions and thus to large accelerations. These can result in accidents on cargo and on passenger ships with consequent damages. This paper proposes a more realistic modeling approach of the critical ship motions, including the pertinent nonlinearities. One of the main goals is to investigate the ship accelerations during maneuvering tasks in irregular in waves. Ship maneuvering performance is typically predicted based on calm water assumptions. However, since the ship always sails in waves, the maneuvering performance in a seaway condition may be significantly different from that in a calm water condition. While the ship is steering in waves, large unexpected accelerations can arise due to the combinations of different motions.The numerical model called LaiDyn is used to investigate ship large accelerations, in heavy sea states. LaiDyn is a six-degree of freedom dynamic model, in time domain. The accelerations, in some relevant points, are evaluated taking into account all the motion components of the ship during maneuvering tasks in waves.