ABSTRACT This paper presents the development of a machine learning (ML) algorithm to predict the hydrodynamic coefficients to calculate the motion behavior of a vessel in frequency domain. The aim is to develop a less laborious and faster method compared to the conventional procedure for determining the hydrodynamic coefficients for added mass, damping, and excitation forces by radiation-diffraction models with linear potential flow solvers based on Boundary Element Methods (BEM). Physics-informed machine learning was utilized to incorporate physical laws directly into the ML models, ensuring accurate and physically consistent predictions. The ML-algorithm is trained and validated with a database created by the software ANSYS AQWA. The approach is performed on the Jack-Up Vessel(JUV) Innovation, owned and operated by DEME.

ABSTRACT Battery electric propulsion represents a highly promising avenue for the decarbonization of inland waterway (IWW) transport. This paper thus examines the potential for electrifying IWW vessels using their operational profile derived from Automatic Identification System (AIS) data. Therefore, a model is developed to derive the energy demands and operational profiles of IWW vessels, which is then used to quantify the potential for battery electric propulsion systems without any adjustments to the vessels' operational profile, thereby ensuring the continued economic operation of the vessels. Moreover, a linear programming model is developed with the objective of minimizing charger power, and its technical feasibility is evaluated. The findings indicate that hybrid battery electric systems can supply between 35% and 70% of the propulsion energy in the majority of vessels. The necessary charging powers typically fall within the range of 100 to 200 kW. It may also be feasible to implement a fully electric propulsion system for a proportion of the IWW fleet. In particular, small passenger vessels such as ferries exhibit considerable potential in this respect, with median battery sizes of 731 kWh and requisite charging powers of under 100 kW.

ABSTRACT Long and flexible offshore wind turbine blades are easily damaged during extreme wind conditions (typhoon or tornado). A parametric study was conducted in this work using the finite element method to study the effect of stiffener configurations, including stiffener number, thickness, and spacing, on the aeroelastic response and buckling of the wind turbine blade by modeling the National Renewable Energy Laboratory (NREL) 5 MW blade structure design. This study investigates wind turbine blade stiffeners' buckling behaviour and natural frequencies. The results show that the critical buckling load value increases significantly as the number of stiffeners, stiffener thickness, and spacing width between stiffeners increase. The modal analysis results show that the variation in the number and thickness of stiffeners increases the natural frequencies of the flaps and torsional modes but decreases the edgewise mode. Variation of the distance between stiffeners increases the flapwise and edgewise modes' natural frequencies.

ABSTRACT An analysis of the regulatory framework for inland navigation indicates that the present definition of Master is one of the major obstacles to the implementation of autonomous shipping on inland waterways in Europe. The paper dissects the definitions of Master as given in the ‘European Code for Inland Waterways’ and the German regulations ‘Binnenschifffahrtsstraßen-Ordnung’ and identifies the obstacles to unmanned and/or remotely controlled shipping created by these definitions. The identified obstacles are also analysed within the context of the vessel automation taxonomy of the Central Commission for the Navigation of the Rhine. Consequently, the recommendations are given on how to modify the definition of Master so as to include all levels of autonomy and account for the implications of the current as well as future technological developments. The main hypothesis of the paper is that the Master should not be ‘removed’ from an autonomous vessel but redefined instead.

ABSTRACT This paper explains the need for the new surface stability regulation recently developed for the submarines of the German Navy and gives an overview of its general setup and main principles. Further, the test setup and main findings of open water model tests using two submarine hull forms on Eckernförde Bay are presented, which contributed towards the development of the new standard. Building on this introduction of the model tests, the results of an exemplary test run at specific combination of speed, stability, sea state and encounter angle are compared via statistical analysis with seakeeping simulation results using E4-ROLLS, a potential flow theory-based computation method. The comparison aims to check the suitability of E4-ROLLS for analyzing stability-dependent large-amplitude roll motions of surfaced submarines in natural seaways. The quality of results is discussed, whereby limitations of the simulation method are pointed out and the relevance of the presented research becomes apparent.

ABSTRACT Steady manoeuvring forces and moments over a generic submarine hull form (SUBOFF) at various angles of incidence were investigated through scaled model tests in the Wind Tunnel Facility at the Naval Science and Technological Laboratory, India. Measurements were performed for a range of angles of incidence in angle of attack (±18°) and drift (±18°) including control surface deflections (±15°) on a 1.372 m model at Reynolds number 1.7 × 106. The present study at angles of incidence is to gather steady-state force, and moment data and validate such load measurements performed in a Wind Tunnel. The particulars of the SUBOFF model, experimental facility and measurement technique, test results for load measurements and estimated hydrodynamic coefficients are highlighted in the paper. The measurement data generated from the above studies will complement the current research on hydrodynamic characteristics for submerged bodies both computationally and experimentally.

ABSTRACT The International Maritime Organization rule-making process utilizes a set of guidelines for the so-called Formal Safety Assessment (FSA). This process is based on a risk assessment and its purpose is to ensure that the risk to human health and life and to marine environment is tolerable. A central instrument in the FSA methodology is known as ALARP (As Low As Reasonably Practicable) principle which ensures that the risk is controlled in a rational and cost-effective manner. The FSA Guidelines recommend the use of monetary thresholds for performing the cost evaluation and provide an example of indices for measuring the cost efficiency. For risks involving fatalities, these measures require the use of a monetary threshold derived from the concept of Cost of Averting a Fatality (CAF). Due to the linkage to economic parameters, this threshold needs to be updated regularly to allow for correct cost-benefit assessment in the FSA context.

ABSTRACT We investigated the effects of the steady wave force variations generated by oblique motions upon ship manoeuvre estimations, using a numerical simulation that incorporated only steady wave forces into a three-degrees-of-freedom conventional modular mathematical model in calm water. The investigation was conducted for a very large crude carrier undergoing course-keeping manoeuvres in regular short waves. The steady wave forces in the simulation were provided via two methods, depending on the experimental data and the presence or absence of a ship drift angle. The simulation was validated via a free-running model test; this involved various rudder effectiveness conditions for the ship model and full-scale ships, both with and without engine limits. Through this validation, we showed that the steady wave force variations generated by oblique motions are non-negligible when accurately estimating the manoeuvres of full-scale ships in short waves, although they are negligible for ship models.

ABSTRACT This paper presents an experimental study of a passive version of the Water-jet vortex generator to reduce the drag force over a NACA 661-012 hydrofoil. The passive blowing used the overpressure zone at the leading edge of the hydrofoil’s lower surface as a source of water jets that create jets on the upper surface of the hydrofoil using the blowing tubes. The experimental tests were carried out in the towing tank in Universidad Politécnica de Madrid (UPM) with a hydrofoil model with a 250-mm long chord at Reynolds numbers of (1.4 105 < Re < 2.8 105). It was found that the passive water-jet vortex-generator reduces the drag force with a slight lift decrease.

ABSTRACT High-speed planing craft operating in real seaways encounter high impact loads. The extreme motions and accelerations resulting from such impacts adversely affect the structure of the craft and its payload as well as pose a risk to the crew on-board. Limiting craft speed according to the sea state using a speed-wave height operational envelope might ensure structural integrity and greatly improve safe navigation. Accurate estimation of motion and acceleration of planing craft in a seaway is a key requirement in developing reliable and usable allowable speed vs. wave height operational curves. In this paper, the Motion Assessment of Planing Craft in a Seaway (MAPCS) tool, a nonlinear time-domain approach vs. several existing approaches based on experimental, empirical and classification societies’ formulas for vertical accelerations and speed vs. wave height limit curves are compared. It is found that the MAPCS approach provides more realistic estimations compared to the commonly employed methods.