A mathematical model was proposed for simulating the ship maneuvering in a seaway. The mean wave drift forces and moment due to irregular waves were added into the MMG model to simulate the wave effects. The influences of the limited propulsion power on the ship maneuverability was also accounted for. Numerical simulations were performed using a full scale S-175 container ship under sea states 4 and 5. The results showed that a limit of propulsion power may significantly attenuate the ship turning ability, especially in high sea states.
Ship maneuvering in waves has been increasingly investigated in recent years. Although the physical experiment is still regarded as the most reliable way to investigate ship maneuverability in waves, there are more and more studies providing practical mathematical models of ship maneuvering prediction. Generally, the state-of-the-art methods for predicting the ship maneuvering in waves can be classified into the method based on the mathematic model and the method based on the direct CFD simulation.
The mathematic model of ship maneuvering in waves are typically formulated by encapsulating the calm water maneuvering model and the wave loads. Related studies have been conducted, for example, by Skejic and Faltinsen (2008), Seo and Kim (2011) and Zhang et al. (2017). CFD methods in principle provide an adequate description of all physics. Based on the CFD simulations, Uharek and Cura- Hochbaum (2016) and Yao et.al (2020) computed mean wave drift loads on the maneuvering ship in regular waves. Carrica et al. (2013) and Wang and Wan (2020) conducted the direct CFD simulations of the turning, zigzag and stopping maneuver of free running ship in waves.
Although these investigations provided useful tools for analyzing the ship maneuvering in waves, most of them were limited to regular wave scenario. For a better understanding of the ship maneuverability in a seaway, it is deemed important to investigate the ship maneuvering in irregular waves. Nevertheless, there are only a few published studies dealt with the ship maneuvering in irregular waves. (e.g. Yasukawa et al, 2015; Seo et al. 2018).
