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This study has developed a numerical tool capable of performing mooring design optimization analysis for floating wind turbine (FWT) platforms. The numerical model is capable of: i) correctly model the physical behavior of a moored FWT platform and ii) run at a low computational cost (i.e., faster than real-time) allowing for the evaluations of many different mooring configurations. The numerical model is based on the Cummins-Ogilvie equation of motion. These hybrid frequency-time-domain approach, allows to perform fast time-domain simulation of floating bodies including external forces such as mooring lines or viscous effects. Firstly, the platform’s excitation force and hydrodynamic coefficients are obtained in the frequency domain utilizing a Boundary Element Method (BEM) solver. Secondly, the results from the BEM solver are converted to the time-domain via convolution integral of the impulse response functions to calculate the radiation force and inverse discrete Fourier transform to compute the excitation force. Thirdly, viscous effect are considered via the Morison Equation using empirical coefficients. Finally, the mooring lines are modelled according to the lumped-mass approach, omitting the coupling between internal nodes allowing the system to be transformed into numerous ordinary differential equations that are solved individually. The established numerical tool can be further coupled with a single and/or multi-objective optimization methods (e.g., genetic algorithm, particle swarm optimization, etc.) to perform a mooring design loop for an FWT platform achieving the optimal configuration in terms of platform motions, mooring line tensions and cost.

In recent years, it has become popular for superyacht designs to incorporate large uninterrupted glazed areas in the superstructure. Larger windows increase the amount of natural light that enters the yacht and add to the yacht’s aesthetic appeal and exclusivity. Cruise vessels and other types of passenger ships have seen similar trends. However, window panes are currently isolated from the structural loads within a vessel and their dimensions are restricted by the presence of a frame as a conventional load-bearing structural component. The use of load-bearing glass components presents a solution to this problem as it can also add to the strength of a ship’s structure, thereby reducing the extent of conventional structural materials such as steel or aluminium profiles. Major challenges exist for the use of glass as a load bearing component in a ships’ structure. Even though a solid scientific background has been established for the structural use of glass in structures on land, a lack in knowledge exists of how the challenges in the marine environment can be addressed. This paper gives an overview of the requirements of a ship structure, and more specifically yacht structures, and describes the challenges associated with using glass as a fully integrated structural component. Further implications for the integration of structural glass in a superyacht structure are also discussed and suggestions for a possible design approach is presented.

Belgian Offshore Wind Farms are located in area where tidal current speed is significant. Therefore, it is important to understand the interaction between waves, current, and the structure to assess wave field behaviour around the monopile. In order to properly assess the wave field around the monopile, preliminary study is conducted by investigating the wave and current interaction. Generation and absorption of wave-current condition are performed with modified OpenFOAM Waves2Foam library where the current velocity is superimposed on wave velocity. In the simulation region it is noticed that wave-current interaction is occuring. The wave length is found to get shorter in the similar value of theoretical estimation in the opposing current cases. However, the wave height increment is found to be lower than the theoretical estimation. Thus the wave height modification in velocity superposition requires further research investigation

Traversing the river Seine in Paris is challenging for inland ships due to the density and diversity of local traffic (cargo and passengers) and the variety of manoeuvres that are encountered. On top of that, there is a high number of historically important bridges, where traffic has to pass underneath narrow arches, while taking into account delicate current conditions on a bending trajectory. Some decades ago, regulations concerning the maximum ship dimensions depending on the water level of the river were put in place to ensure the safety of navigation. However, with a growing interest in inland waterway transportation (economic, environmental and logistical advantages compared to rail or road transport) and with new types of ships plying the waterway, the question arose whether the regulations are still up to date. To this end, the waterway authority, Voies navigables de France (VNF), commissioned a study to assess the relevance of these regulations when present and future vessels of varying types and dimensions cross Paris. The study was carried out by the Maritime Technology Division at Ghent University in cooperation with International Marine and Dredging Consultants (IMDC), Flanders Hydraulics Research and Siradel. This poster presents how ship manoeuvring simulators are used to assess the maximum dimensions of ships crossing the Seine in Paris. Real time simulations were carried out by skippers familiar with the crossing of Paris and the analysis is based on their feedback as well as a selection of safety criteria. The simulations have shown that the main bottlenecks are related to the succession of passages under narrow bridges with non-aligned openings. Maximum water levels for which safe passage is possible, were determined for each ship type and compared with the actual regulations. Finally, recommendations have been formulated, which were then discussed with VNF and the stakeholders.

In order to improve the performance and the energy efficiency (rudder actions) of the ship control system in presence of changing environmental conditions and system uncertainty, this paper develops a novel adaptive fuzzy-PID course controller with a dynamic compensator and a nonlinear feedback for the autonomous surface ship. Firstly, an adaptive PID control strategy, whose control parameters are real-time adjusted by the fuzzy system, is designed to achieve the optimal control effect and the robust performance. Then, considering the uncertainty and unpredictable external disturbances, the Least Square Support Vector Machines (LSSVM) approach is employed to online identify and suppress the disturbances for the purpose of compensating the Fuzzy-PID controller. Furthermore, the nonlinear feedback is added in the control law to deal with the control inputs, and then the whole control system is named as “NFPL”. The effectiveness and quality of the designed controller are investigated in the numerical simulations. Results demonstrate good adaptability and robust performance of the designed control system in spite of the existence of the time-varying environmental disturbance, and the advantages in the reduction of the settling time and rudder energy consumption as well as fast response are also verified. China Scholarships Council Ghent University

Ports want to ensure safe and reliable loading operations for all ships. Increase in ship sizes, especially container ships, can potentially cause unsafe mooring situations. For ships moored at quay walls, there is also a lack of international guidelines and recommendations for mooring arrangements. This paper presents a case study for a moored containership being passed by a vessel of identical dimensions. The behaviour of the moored ship is simulated using UGent’s time-domain mooring software Vlugmoor. Starting from a well-balanced arrangement used currently in daily operation, three optimisation steps are presented, aimed at lowering the ship motions, which are critical. The first step explores the impact of changing line positioning to reduce line length disparity and improve efficiency in critical force directions. The second step considers a lower fore mooring deck to reduce line steepness, as well as additional winches below the bridge and funnel. The third step proposes replacing medium stiff lines with a very stiff HMPE line, combined with an elastic tail. The effect of these optimisation steps on the ship motions are presented and compared with predictions based on efficiency parameters. These factors express the capability of the configuration to deal with positive and negative surge forces. It is shown that applying these optimisation steps can significantly improve the safety of a moored container ship during a ship passage.