Ship accidents that entail flooding may lead to disastrous consequences which could be avoided or mitigated based on the knowledge of damaged ship dynamics. The dynamic behaviour of a damaged hull is a complex phenomenon involving the interaction of the flooded water and the ship motions. The presence of a damage opening allows water flow into and out from the compartment, which further complicates the mathematical description of the problem. A fast simulation method, based on the lumped mass approach, is developed and presented. The lumped mass path in space depends on free-surface inclinations that differ from the ship angles of the roll and pitch. The viscous effects in the floodwater dynamics are implemented based on the model for the dissipation of the energy of standing waves in rectangular rooms. The method applies to both the transient stage of flooding and to the dynamic behaviour of a flooded ship in regular waves. In the first case, viscous effects are implemented considering the water in the compartment variable with time. Several case studies are carried out on three different hull models: Transient stage of flooding, roll decay of the damaged hull, and steady state responses in waves are simulated and compared with available experimental data.

The article deals with a simulation approach to the representation of the ship motions in waves, interacting with the propulsion system behavior (diesel engine and propeller). The final goal is the development of a simulator, as complete as possible, that allows the analysis of the main engine thermodynamics in different sea conditions, also in the unfavorable event of dynamic instability of the hull, and the correct management of the other propulsion components. This latter aspect is particularly interesting in some of the last new energy solutions for decarbonization of ships, concerning, for example, auxiliary electric motors, powered by batteries, to support the traditional diesel-mechanical propulsion (especially in heavy weather conditions). From this point of view, a proper analysis of the engine dynamic performance, affected by particular sea states, is fundamental for a smart management and control of shaft generators/auxiliary electric motors, batteries, etc. To this end, the work presents and highlights the main features of a ship simulator, suitable for the study of the new propulsion solutions that are emerging in maritime transport. Some representative results will point out the complex non-linear behavior of the propulsion plant in waves. Moreover, a parametric roll scenario will be investigated, in order to highlight the capability of the conceived simulator in modeling the effects of the dynamic instability of the hull on the propulsion plant.

This paper presents a numerical model for the smart detection of synchronous and parametric roll resonance of a ship. The model implements manoeuvring equations superimposed onto ship dynamics in waves. It also features suited autopilot and rudder actuator models, aiming at a fair depiction of the control delay. The developed method is able to identify and distinguish between synchronous and parametric roll resonance, based on the estimation of encounter wave period from ship motions. Therefore, it could be useful as a smart tool for manned vessels and, also, in the perspective of unmanned and autonomous vessels (in the paper it is assumed a hypothetical remote crew). Once the resonance threat is identified, different evasive actions are simulated and compared, based on course and speed change. Calculations are carried out on a ro-ro pax vessel vulnerable to parametric roll. We conclude that, in roll resonance situations, and in the absence of roll stabilisation systems on-board, course change could be the most effective countermeasure.