During initial ship design, a vessel's manoeuvrability and propulsion system performance are investigated separately, ignoring the interconnection that actually takes place in real conditions. In this paper, a new simulation tool has been developed by coupling the propulsion system and seakeeping models. The ship's manoeuvrability is investigated by using a non-linear 3-DOF manoeuvring model in calm water, whilst a mean value approach model is used for the simulation of the vessel's propulsion system performance. The main outcome of this method is to validate the simulation tool performance by using the available ship's turning circle sea trials and to simulate her performance and manoeuvrability in shallow water condition. The results include the consolidation of the ship trajectories and the performance of the propulsion system components during turning in various sea depths.
Introduction of lower emission limits for the environmental protection stipulates the installation of more efficient systems. In the quest of the balance between efficiency and safety, IMO has recommended guidelines on the calculation of the minimum required installed propulsion power (IMO, 2013). According to these guidelines, the minimum power is estimated based on the propulsion system's performance that maintains the manoeuvrability of the ship.
Meanwhile, statistics indicate that the majority of the groundings and collisions in maritime world occur in coastal areas (EMSA, 2016). In such restricted areas, flow patterns changes, leading to alterations of ship's manoeuvring characteristics. Therefore, the manoeuvring behaviour of the ship, as well as the propulsion system performance during manoeuvring shall be investigated, identifying the interaction of the propulsion system performance to the ship's navigation during manoeuvring.
Due to the high cost of the sea trials and model tests, numerical methods have been developed for the estimation of the ship's trajectories and propulsion system performance, predicting the manoeuvrability of ships in calm water. These time - domain numerical simulation tools could be used from the early design stages of the ship in order to investigate whether it complies with the relevant IMO criteria and certify that the selected engine has adequate power.