The purpose of this study is to assess the quality of the manoeuvre prediction of a twin-shaft naval vessel by means of a time-domain simulator based on Computational Fluid Dynamics (CFD) hydrodynamic coefficients. The simulator uses a modular approach in which the hull, rudders, appendices and propellers are based on different mathematical models. The hydrodynamic coefficients of the hull in the bare and appended configurations are computed using virtual captive tests performed with an open-source CFD code: OpenFoam. This paper demonstrates that the application of the CFD hydrodynamic coefficients led to a good estimate of the macroscopic characteristics of the main IMO manoeuvres with respect to the experimental measures. The adopted test case is the DTMB 5415M frigate both with and without appendages. This test case has been investigated in several research studies and international benchmark workshops, such as SIMMAN 2008, SIMMAN 2014 and many CFD workgroups.

The design process for motor yachts primarily relies on the experience of designers, who draw upon their knowledge gained from working on similar hull forms. However, when a new concept is to be developed, the experience garnered from standard platforms may not suffice for achieving a successful design within a short timeframe. Designing a motor yacht involves considering multiple aspects of ship hydrodynamics, including resistance, propulsion, seakeeping, and maneuverability. While these factors have been extensively discussed for different types of ships, a comprehensive joint investigation of hulls, such as those of motor yachts, is noticeably absent in the available literature. This paper aims to fill that gap by providing guidelines for the design of motor yachts with lengths ranging from 20 to 40 m. As part of a preliminary study, a series of 15 yacht hulls were developed, starting from a reference hull form. The resistance, seakeeping and maneuverability performance of these hulls were assessed under specified environmental conditions and speeds, following the ISO 22834:2022 guidelines for comfort assessment. The calculations produced response surfaces detailing the hydrodynamic properties for this series of yachts as functions of the main dimensions of the hulls. Ultimately, these responses assist in identifying optimal design solutions for the main dimensions of a new motor yacht within the 20 to 40 m length range.

Accurate prediction of ship manoeuvring performance requires reliable hydrodynamic modelling and a careful treatment of several factors that may significantly influence model precision. In this study, 4-DoF mathematical manoeuvring models have been built with both EFD-PMM test data and virtual PMM results coming from CFD simulations. Heel effects are considered by introducing heel-related hydrodynamic derivatives, which helps improve the model accuracy especially at low transverse metacentric height (GMT) conditions. Consistently, experimental free-running test results with various approach speeds, rudder angles and GMT are exploited for the validation purpose of the manoeuvring modelling. Beyond the manoeuvring model development, several modelling choices are systematically analysed for improving prediction accuracy and computational efficiency. The influence of CFD model complexity is investigated to seek for the possibility to reduce computational cost with acceptable precision, while the use of realistic combined drift and yaw conditions is explored to minimise the number of required simulations. Furthermore, the necessity of ship speed consistency is studied and a heel angle correction is introduced to improve the model accuracy and capture the nonlinear heel effects. The proposed framework provides practical guidelines for balancing model precision, physical fidelity and computational efficiency, supporting the development of robust CFD-PMM based manoeuvring models.