Accurate simulation of non-linear free-surface wave interaction with structures as if in the open sea requires truncation of domains for computational feasibility. In absence of special boundary measures, truncation introduces artificial boundaries with spurious wave reflection back into the computational domain. The common way to prevent reflection is by means of dissipation zones, which are often larger than the domain of interest in order to achieve sufficient accuracy. Local absorbing boundary conditions pose a potentially more efficient alternative, but are limited in accuracy due to corners on Cartesian domains (advantageous for future implementations of Volume-of-Fluid methods). This work proposes a methodology that preserves a Cartesian structure of the interior grid, while mapping to a circular domain boundary through the use of curvilinear coordinates. On the circular boundary, higher-order absorbing conditions can be applied without corner limitations. The linearized shallow water equations are discretised using a staggered finite volume discretisation. Two second-order Engquist-Majda boundary conditions, extended with generating wave capabilities, are expressed in the coordinate system, implemented and benchmarked using a first-order Sommerfeld boundary condition, using a centred and off-centre source configuration. Results demonstrate that the methodology allows consistent implementation of higher-order absorbing boundary conditions with low spurious reflection.

The design of large catamaran sailing yachts requires careful balancing of aesthetics, comfort, and performance, with the wet deck geometry playing a decisive role in resistance, motions, seakeeping, and slamming behavior. In this work, a method is proposed to enhance the estimation of wet deck geometry for large catamaran sailing yachts in an early design stage. While the operability of such catamarans is primarily driven by passenger comfort, the influence of wet deck geometry on motions, seakeeping, and slamming was identified as the main factor limiting vessel operability. Four key (non-dimensional) parameters, including wet deck height (h/L), hull separation (s/L), demihull beam-to-draft ratio (b/T ), and the starting position of the wet deck relative to the bow (Lswd/L), were systematically varied, resulting in 295 design configurations. Vessel performance was evaluated using a comfort operability index (cOI), which quantified the percentage of time a vessel could operate within the predefined comfort limits. The cOI was derived from seakeeping criteria, including effective gravity angle, motion sickness incidence, vertical and lateral accelerations, and slamming probability. Response amplitude operators (RAOs) at the center of gravity of each design were obtained using Maxsurf Motions, supplemented by an in‑house Python post‑processing tool to evaluate the seakeeping criteria across multiple onboard locations. An engineering correction was applied to heave motions in beam seas. The analysis covered three vessel lengths (50, 60, and 70 m), three headings (beam, bow‑quartering, and head seas), and representative sea states for the Mediterranean (Jonswap spectrum) and Atlantic (Bretschneider spectrum). Results showed that increasing vessel length consistently improved cOI, particularly in head and bow‑ quartering seas. Among the wet deck parameters, s/L strongly influenced lateral acceleration and effective gravity angle in beam seas, while b/T and Lswd/L significantly affected motion sickness incidence and vertical acceleration in head and bow‑quartering seas. Higher b/T ratios generally improved comfort, though the impact depended on vessel length, heading, and sea state. Lswd/L exhibited an initially positive but ultimately negative influence at higher ratios, while h/L showed an impact only in beam seas under Mediterranean conditions. Differences between the Jonswap and Bretschneider spectra were modest, with the Atlantic spectrum yielding slightly higher cOI values and reducing the limiting role of motion sickness incidence. Across all conditions, forward onboard locations emerged as the most critical for limiting comfort. By quantifying the impact of wet deck geometry parameters on operability, this study established a methodology that provided deeper insight into the influence of wet deck parameters during the early design stage. While the present analysis excluded sail forces and steady heeling angles, these aspects could be integrated into the framework of this study in future research.

This study investigates the effect of dynamic properties of a structure on the magnitude of impacts loads of breaking waves. A literature review in the field of violent wave impact on flexible structures is done. From this review, it is concluded that the hydro flexibility of structures have great impact on the fluid-structure interaction. In earlier studies, it is found that models of constructions in breaking waves are not accurate yet, using knowledge that is available up until now. There are studies that show suggestions of influence on the structures own properties. However, no extensive research had been done in this field. That is why the main objective of this study is to research if the natural frequency of a construction is of influence on the impact force of violent waves.

To answer the research question, a model is made and an experiment is carried out. The model consists of two parts, first a pendulum is used to represent a simplified structure to interact with a breaking wave. Using the model, a simulation of pendulums with different natural frequencies is done. The pendulums interact with the same wave each time. The second part of the model consists of a beam that is impacted by a breaking wave. Simulations are carried out where beams with different natural frequencies are impacted by the same wave.

To verify the model and further elaborate on the research question, an experiment is done. This experiment is done in the Sloshing rig at the faculty of Mechanical Engineering at the TU Delft. During the experiment, four different plates with different natural frequencies are used. They are exposed to the same wave impact each time. The model and the experiment results are compared and used to form a conclusion.

It is concluded that wave impacts are of higher magnitude on structures with a higher natural frequency. The difference between the measured and predicted forces indicates that the fluid- structure interaction of these plates lead to this difference. This can be explained by the different fluid- structure interaction for plates with different natural frequencies. If velocities of the plates with higher natural frequencies are higher, the Morison component of the impact force becomes larger. Therefore these impacts can become higher than for other structures. As the natural frequency of the plate increases, the results show relatively higher measured deflections as well.

Inland shipping is widely acknowledged as a sustainable mode of transportation due to its low energy consumption and emissions in comparison to road and rail transport. However, with growing concerns around reducing emissions in the transportation sector, there is pressure to address environmental issues associated with inland shipping. In the Netherlands, a Green Deal has been formulated to outline the goals for reducing CO2 emissions by 2030 and other environmental pollutants by 2035 in inland navigation, to enable us to take the next step towards a climate-neutral society by 2050. This increasing pressure raises the question of how to get insight of the energy consumption and the associated emissions from inland shipping. To date, an accurate method is lacking that is able to estimate the total resistance, the propulsive power and in turn the energy consumption in shallow water and thus to quantify the CO2 emissions. Over the years, several power estimation methods have been developed for inland vessels, with the Rijkswaterstaat power estimation method being one of the most widely recognized. Recently, Backer van Ommeren (2019) investigated the Rijkswaterstaat power estimation method and found that certain assumptions and parameters used in the method were not well-founded, and that some approximations were unnecessary.
The main objective of this study to conduct a comprehensive literature analysis on Backer van Ommeren (2019) comments and recommendations regarding the Rijkswaterstaat (RWS) or Bolt (2003) method in order to clarify to what extent these recommendations will indeed improve the Bolt (2003) method or if an alternative power method should be proposed instead. This will be accomplished through a comparison process of the power results as a function of sailing speed, water depth, and channel dimensions for various types of inland vessels, utilizing the selected methods that will be derived from the literature study along with Backer van Ommeren (2019) recommendations applied to the original method. After coding these methods in Python and analyzing their results, the best practice(s) that will be derived from the test cases, will be implemented on two classes of motor vessels an M6 and an M8 to estimate the resistance and the power and then they will suggest to Rijkswaterstaat for potential future use.
To achieve the main research objectives, the following research was conducted. Initially, a literature analysis on the available resistance methods, how they consider and divide the several resistance components, and which are the shallow water effects that affect them, was done in order to evaluate their performance in terms of power estimations. Secondly, the comments made by Backer van Ommeren were presented and analyzed. Specifically, he investigated various formulations for calculating the return flow, water level depression, and characterizing the waterway as normal, narrow, wide, or very wide. This study was accomplished through the use of specific power efficiency and resistance coefficients. Based on his study, he derived a method, the Backer method (Backer van Ommeren, 2019) and suggested a number of formulas to be further tested. After completing the literature review, the findings lead to the selection of the power methods that will be treated in this thesis and the kind of improvements that will be applied to the original Bolt (2003) method.
Subsequently, from the literature study and Backer van Ommeren (2019) review, four methods were derived to be simulated and tested in this thesis. These methods include the TU Delft method, Bolt method with speed correction, Bolt method modified by Backer, and Backer method. The simulation was achieved with two rounds of tests that are conducted, firstly the “Academic test case” and secondly the “Real-world test case”. In the “Academic test case” five methods were simulated and the most promising that met specific criteria are selected. Then, in the “Real-world test case” the selected methods as they were derived from the “Academic test case”, were further evaluated for the selection of the best practice(s). The first round of tests is applied to two classes of motor vessels in narrow and wide waterways with shallow, intermediate and deep water depth conditions and the results include the total resistance and the brake power while the second round simulates only one motor vessel of class six in wide waterways for the same depth conditions as previously and the outcome includes the delivered power. The “Real-world test case” is divided in two parts. The first part includes the comparison between the estimated and the measured delivered power in order to assess the performance of the methods with the real data. The second part evaluates the performance of the methods in the presence of a current flow, by comparing the fuel consumption in upstream, downstream and round trips.
The evaluation of the methods in a real-world test case led to a number of conclusions, and the best practices were recommended accordingly. It should be noted that the comparison process was based solely on a single real-world case, utilizing a singular set of real data. It is important to be conducted additional comparisons across multiple real cases in order to increase the understanding of the accuracy of the various methods being compared. In the context of power estimation in shallow water, both the Bolt (2003) method and TU Delft method(Jiang, Baart & van Koningsveld, 2022) have demonstrated remarkable accuracy in their predictions while Backer method and Bolt method modified by Backer are not recommended for power predictions. Notably, Bolt (2003) method has proven to be effective in estimating power within a speed range of 2.5m/s to 3.5m/s while TU Delft method (Jiang, Baart & van Koningsveld, 2022) showed accurate predictions within a speed range of 2.5m/s-4m/s (accurate as defined within 20% of the observed value). Regarding the intermediate and deep water conditions, only TU Delft method (Jiang, Baart & van Koningsveld, 2022) showed acceptable performance in power estimation again for sailing speeds varying 2.5 m/s – 5 m/s. The power demand at very low speeds for all the three methods display a considerable deviation between the estimated power output and the actual values, surpassing the acceptable rate of 20%. This can be attributed to two reasons. At low speeds, the interaction between a sailing vessel and the boundary layer becomes more pronounced, causing the ship to experience turbulent effects that dominate the boundary layer more intensively. As a result, the vessel experiences increased resistance, requiring more power. Secondly, in actual operating conditions, a ship has a minimum power engine setting that is dependent on the engine characteristics. So, when the ship is moored and the "hotel mode" is on, as the ship not having a separate auxiliary power unit, a propeller brake is used to allow the turbine to continue running and generate power without the propeller spinning. This effect does not consider by the power estimation methods that rely on parameters such as sailing speed and water depth. The Backer (2019) method demonstrated satisfactory performance in predicting resistance and power for both types of motor cargo vessels within narrow waterways. This method effectively accounted for the variations in depth by accurately estimating lower resistance and power demand as the depth increased. However, Its accuracy in wide waterways diminished due to the equations' unsuitability for such conditions, by generating nearly identical resistance and power estimations for the three different water depths. Based on the aforementioned restriction, it is not recommended to employ this particular approach for subsequent power estimations. As regards the Bolt method modified by Backer performs poorly in estimating resistance and power across narrow and wide waterways with varying depths. It consistently yields similar results for shallow, intermediate, and deep depths at a specific sailing speed. Therefore, it is not recommended as an improvement to the Bolt method. In the presence of current flow, three methods have shown promising results. Specifically, the TU Delft method (Jiang, Baart & van Koningsveld, 2022) is recommended for motor vessel, as it produces deviations from real measurements of 0.93% for upstream, 1.36% for downstream, and 0.45% for round trips. Also, TU Delft method (Jiang, Baart & van Koningsveld, 2022) is recommended in case of pushed and coupled convoys as it has been found to produce the smallest deviations in upstream sailing, with a maximum of 3.9% while the deviations observed for downstream sailing and round trips are around 1.9%. Bolt (2003 )method and Bolt method with speed correction, were found to produce acceptable deviation rates of around 7% for upstream trips, with the benefit that these methods require less detailed input data. Nevertheless, for downstream and round trips, the deviations were much higher, reaching up to 80% and 30%, respectively and event that requires additional investigation and validation.

During specific operations, offshore marine contractor Heerema Marine Contractors reduces the draft of their Semi-Submersible Crane Vessel (SSCV) such that the floaters are submerged in close proximity to the free surface. This draft is also known as inconvenient draft. At this draft the motions of the vessel do not fully comply anymore with the computed prediction using linear diffraction theory. A proper motion prediction is required to ensure a safe execution of the offshore operation. The key issue is the submerged part of the floater, since discrepancies occur as soon as there is only a small water column on top of the floaters. Motion RAOs are computed via the hydrodynamic coefficients and wave loads. The reason why this leads to discrepancies in the motion RAO is not yet known. In addition, qualitative hydrodynamic data should be gathered for an object submerged in close proximity of the free surface.
Therefore, in this study the cause of the discrepancies in motion RAO is studied on an experimental basis for an object submerged in close proximity to the free surface. The scope is narrowed down to a two-dimensional cross-section of a SSCV-floater. Numerical simulations using linear diffraction theory are performed in WAMIT. The results are compared to experimental data obtained via model tests performed at the towing tank facilities at the faculty 3mE at Delft University of Technology.

Based on experimental data is concluded that linear diffraction theory does not predict physical phenomena that satisfy the boundary conditions and that underlie principles of the theory. Despite the fact that the experimental data does satisfy the boundary conditions of the numerical simulation, discrepancies occur at the hydrodynamic coefficients and wave load. As a result, it can be concluded that linear diffraction theory malfunctions at the inconvenient draft region, and therefore is not the correct theory to determine RAOs for an object on inconvenient draft.
Discrepancies in motion RAO are found to be dominated by the discrepancies the wave load, except for the frequency at which the added mass equals negative inertia of the body. Discrepancies for added mass are less significant than for the damping coefficient and wave load. At higher frequencies inertia becomes dominant over damping and damping deviations affect the RAO less.
The pitch motion about the center of the cross-section does not represent a rotational motion about same the degree of freedom for an SSCV. However, it allowed to experimentally investigate the global numerical extremes. In addition, it led to the finding that it seems that the rotational data is more affected than the heave data.

There is a strong suspicion that poles in the complex plane are the cause of the discrepancies in the hydrodynamic data, which result of the used Green's function by Wehausen and Laitone. This suspicion is based on characteristics of the numerical data in combination with findings in literature and the experimental data, accumulate.

Currently, an approach that makes use of free surface damping is applied to predict the motion of an SSCV at inconvenient draft. Based on experimental data can be concluded that the use of free surface damping without further modifications does not result in an accurate motion prediction.

Lastly, the effect of nonlinearities when increasing the oscillation or wave amplitude. The wave load is found to be more prone to nonlinear effects than the hydrodynamic coefficients.The force signal remained dominantly harmonic, but higher harmonic forces did show up. Furthermore, with the exception of most tests at the largest tested submergence, higher harmonic waves were measured and visually observed during the tests. These higher harmonic waves arose at the transition from the shallow to deep water regime and vice versa. These forces were found to have hardly any effect on the force signal.

During berthing operations of ships, the horizontal thrusters cause a hydraulic load on the quay wall and bed. This could eventually lead to scour holes in the bed, which may affect the structural integrity of the quay wall. This thesis is about a numerical simulation of a bowthruster jet which is deflected by a quay wall and the focus of this study will be on the resulting bottom velocities. In 2019, field measurements were executed with an inland vessel and the measured bottom velocities were low compared to the design guidelines. The goal of this study is to simulate the field measurements in a numerical model to gather more knowledge about the flow field induced by bowthrusters next to quay walls. The obtained numerical results are compared to the field measurement and to the design guidelines of PIANC. As it turns out, the velocity sensors probably did not measure the maximum bottom velocity during the field measurements, since they are located slightly above the highest velocities at the bottom, as predicted by the numerical simulations. The maximum bottom velocities from the numerical simulation are similar to the expected near-bed bottom velocities by PIANC. However, there is room for improvement in these design guidelines, e.g., adjusting the efflux velocity for tunnel thrusters to account for the variation in cross-sectional area between propeller and tunnel exit.

New offshore wind farms are moving farther away from the shore; to locations characterised by adverse weather conditions. This challenges current maintenance strategies because, besides being further from shore, far-offshore wind turbines need more frequent maintenance and must be accessed in rougher weather conditions. Service Operation Vessels provide high accessibility to far-offshore wind turbines, but they lack multitasking capabilities. Its daughter craft is a valuable asset for unplanned maintenance in the summer when it can operate safely, but it is often not deployable during the winter due to the rougher weather conditions. The main research question is: What are the deficiencies of current DCs, and how can these access vessels be modified to operate year-round at far-offshore wind farms? The results show that the current DC’s deficiencies lie in its current operational requirements. Also, performance in oblique waves is currently riskiest since that is when there are higher vertical accelerations or a combination of vertical and lateral accelerations. Furthermore, wave steepness has significantly more effect on accelerations that wave height. Lastly, future DC designs should be focussed on stable seakeeping performance during transfers rather than high-speed transit. An analysis into the seakeeping performance of four prototypes showed that it is feasible to increase the transfer requirement from Hs ≤ 1.5 m to 2.0 m ≤ Hs ≤ 2.5 m. The catamaran type DCs have a high potential to realise year-round accessibility to far-offshore wind farms due to their resulting performance in oblique waves.

In recent years, ships are expected to improve energy efficiency and reduce carbon emissions. For naval vessels, it is important to be able to maintain their mission profile. It is therefore required to provide real-time advice to the ship’s crew on the optimal speed and propulsion mode settings that include the actual environmental conditions. This paper proposes a novel machine learning approach to establish the ship’s fuel consumption per mile for the actual environmental conditions and develop fuel consumption curves for the various propulsion configurations. The proposed approach uses a multi-layer perceptron (MLP) model to establish the ocean parameters based on the own ship data, with an accuracy of 4.150 %. Using these ocean parameters combined with the own ship data, the fuel per mile is predicted and fuel consumption curves are established using an MLP-model, with an accuracy of 1.551 %. This thesis shows that the proposed approach makes it possible to help a ship’s crew make well informed decisions to reduce their CO2 emissions in real time while still meeting their mission profile. The proposed approach is especially useful for military operators since there is no need for external data sources. Further research is identified to optimize the proposed approach using a dataset containing a higher variety and number of environmental conditions and propulsion modes to improve and validate the fuel consumption curves for the entire spectrum of speeds, environmental conditions and propulsion modes.

The Autonomous Low Energy Replenishment Dredger (ALERD) strives to revolutionize the dredging world. The ALERD operates autonomously underwater, which saves energy during the dredging process and transit. Autonomous underwater operation drives the need of alternative energy facilities. However, due to the energy savings of dredging, alternative energy supplies are possible. A wish of C-Job is that the ALERD operates with zero emissions, and therefore the system should comply with it as well. This introduces the research goal: Devising a sustainable electrical energy supply for ALERD. An additional challenge to the research goal is that the dimensions are not yet established and are still an open question in the research.
The simulation model uses the calculated electric load balance of the Autonomous Underwater Maintenance Dredger (AUMD) and scaling to determine the power balance of the ALERD over various hopper volumes. Furthermore, the operational area has been studied to determine charging/bunker locations and distances. The project requires an annual sedimentation of 12 million m³, including foreshore and coastal replenishment.
To determine the best system, a literature review was done towards the systems. Two key systems came out as the best systems for autonomous and sustainable operation: The Li-ion battery and the Proton Exchange Membrane Fuel Cell (PEMFC). The systems have very different characteristics. Typically, batteries have high costs for the energy storage and fuel cells costs are determined by the nominal power output.
The abovementioned systems were both used in a simulated operational profile of the ALERD. Results from the simulation, suggests that the battery has the optimal performance at 2-3 times dredging per energy cycle, where 4-9 times are the optima for the Hybrid solution. When both systems have charging/bunker stations near the operational area, a dredging cost of €*** per m³ can be achieved for both systems. However, when the ship is charging/bunkering in the port, the costs per m³ increase with €*** for the hybrid and €*** for the battery powered ALERD. This results in a maximal investment of €** million for a local charging/bunker station, to be economically feasible. By making these stations accessible for other purposes, profit can be taken to recoup the investment. It is however expected, that these local stations will not be feasible for the first generation of ALERDs.
When cost development is taken into account, the Total Cost of Ownership (TCO) prefers the hybrid system. Which is a result from the sharply decreasing hydrogen and fuel cell costs. The system also achieves a lower TCO than a conventional dredger, in a manageable time.
A (near) future orientated system has also been considered, the direct-fed ammonia Solid Oxide Fuel Cell (SOFC). It has comparable costs per cubic metre for port bunkering as the other systems, when they are locally charging/bunkering. Furthermore, there are a lot of practical advantages by the use of ammonia instead of hydrogen as fuel. This consists of better fuel handling and easier storage.
Together with the benefits of taking more energy inside the ALERD, it is believed that the hybrid types of ALERD have the best characteristics for coastal maintenance. It depends on the developments of the ammonia SOFC, if it is ready to supply energy to the ALERD, or that the hydrogen PEMFC is the best solution in a hybrid design. Furthermore, the decision depends on the results of the weight and stability study, which is still ongoing. The results could eliminate a systems by its volume or weight. Due to the reserved space and freedom in the ship design, this is however not expected.

The shipping industry has a notable share in global greenhouse gas emissions and other pollutants such as sulphur and nitrogen oxides. Fuel cells and batteries are identified as relatively new technologies for shipping with high potential and hydrogen is also considered as one of the most promising sustainable fuels, especially for smaller vessels. This research contributes to three identified knowledge gaps: (1) the potential of hydrogen propulsion for high-speed craft, (2) the hybridisation of fuel cells and batteries for marine applications and (3) the characteristics of the response of a hybrid fuel cell/battery propulsion system under transient loads. The objective of this research is to analyse these aspects based on a series of time domain simulations of various operational conditions.
A mathematical model of a fuel cell/battery propulsion system is developed in Matlab/Simulink. The developed model is used to analyse the energy consumption for various operational conditions of a test vessel. Based on this analysis, two configurations of fuel cell power and battery energy are selected. If the vessel sails at top speed, the fuel cell power stacks operate at maximum power and the battery operates as power booster. A strong correlation was found between the endurance at top speed and the battery size which is selected. A larger battery has a positive effect on endurance, but it also increases the displacement of the vessel significantly and, hence, required power.
Fuel cells are least responsive and these should be protected against high fluctuations in a short time. A fuel cell can only follow low-frequency transient loads. The battery is required to support in high-frequency load changes. Contrary to the fuel cell, both the battery and PMSM were found to have very favourable characteristics in transient conditions.
Finally, it is concluded that it is feasible to implement fuel cell/battery propulsion on high-speed craft. It is proposed that the fuel cell and hydrogen deliver the majority of the energy and use the battery as power booster and for transient support. Novel energy management strategies can deliver high system efficiencies in both full and part load and this is one of the main advantages of hybridisation.
The implementation of a fuel cell/battery system does, however, come at significant costs in terms of endurance and top speed due to the low volumetric energy density of hydrogen. It should be acknowledged that the functionality of the vessel is reduced. In addition to this, the storage of hydrogen requires some deck space, so the cargo capacity in terms of crew and material is also reduced. Therefore, it is recommended to redefine the user profile of the vessel.

During the energy transition, a wind-assisted ship propulsion system has the potential for increasing energy efficiency according to the ship’s EEDI (Energy Efficiency Design Index) in the short term. However, it would not only make the diesel engine run in off-design condition, but its dynamic behavior due to time-varying wind and waves is still unknown. Hence, for a selected case used in this thesis, a Flettner rotor is chosen to be further evaluated on the system’s dynamic behavior under its favorable wind angle at Beaufort scale 6 and 7.

After modeling the wind-assisted ship propulsion system, it was linearized and normalized around its static operating point. This gives more insight into the system from a frequency-domain analysis via the Bode magnitude plots of engine speed, engine torque, and ship speed to the variation of true wind speed and wakefield induced by wave amplitude disturbance. In addition to the time-domain simulation for understanding the impact of the wind and wake disturbance on the system, the system response spectrum, which was proposed as an alternative approach for analyzing the system’s dynamic behavior, was derived by connecting wind and a derived wake spectrum to the Bode magnitude plots. Therefore, how the energy is conveyed from the marine environment to the system around its equilibrium can be tracked clearly.

Consequently, according to the selected case with a given controller, the results show that the fluctuation of true wind speed directly influences the ship speed, which in turn makes the engine torque be more sensitive to the variation of true wind speed in low-frequency regions. Besides, the engine speed resists to the variation of true wind speed very well due to the controller’s introduction. Although the Flettner rotor generates approximately 44% of thrust at Beaufort scale 7, the true wind speed disturbance does not result in a significant engine loading disturbance compared with the fluctuation of wakefield, which significantly influences the engine speed and torque. It was found that it is related to the frequency region where the wake spectrum overlaps with the system sensitivity function. Within this region, the controller has a relatively poor performance, and thus an engine operating cloud can be noticed in time-domain simulation. However, the ship speed is not influenced significantly by the wakefield disturbance because the frequency region of wake spectrum does not overlap with that of the transfer function where the ship speed is more sensitive to the variation of wakefield. Finally, the sensitivity study implies that a further increase of ship total mass and moment of inertia enlarge the engine speed and torque in the frequency region where the controller does not perform well.

In conclusion, based on the selected case under its favorable wind condition, the potential of the wind-assisted ship propulsion system is still promising. Furthermore, the linearised model is a useful additional tool, and the system response spectrum gives more insight into the system.

The IMO has proposed Just-In-Time arrivals and services as one of the short-term solutions to reduce greenhouse gas emissions in maritime shipping. The Just-In-Time concept allows vessels to optimize their speed during the voyage. If a vessel earlier knows at which time it is requested to arrive at the pilot boarding place, the vessel can adapt its speed to arrive when the berth, nautical services and the fairway are available. Besides environmental reasons, shipping companies as MSC consider the Just-In-Time initiative as a major port call process optimization. It has obvious advantages for MSC since this concept aims to minimise unnecessary ad hoc waiting times and reduces fuel consumption per mile steamed. In the past, it has become clear it is extremely complicated to implement this initiative. Research is required in order to find out what needs to be improved to enable Just-In-Time arrivals and services. The current port call processes must be analysed. As start point, a case study is conducted on the port call processes of the world’s second largest shipping company in the biggest port of Europe. In this study, the current port call processes of MSC container shipping in the Port of Rotterdam are identified and improved in order to enable Just-In-Time arrivals and services. First, an actor-stakeholder analysis is conducted to understand the incentives and relations between actors involved in a port call. Subsequently, this information is used in the process analysis. In this study, the port call processes are analysed by both qualitative and quantitative research. The research has emphasized the complexity of the port call business processes. Actors primarily act on the basis of their own incentives. In order to enable Just-In-Time arrivals and services, collaboration is required among the involved actors. Today, most actors see the benefits of this concept. However, some actors are not willing to share data about their processes since this is considered as sensitive information. In case actors are willing to share data, it can be concluded that the information is not exchanged frequently enough or does often not meet any data standards. As last, this study shows that adaptations are required to the current business process of a port call in the Port of Rotterdam in order to enable Just-In-Time arrivals and services.

Hydro-elasticity is important in the evaluation of a category of wave energy converters (WEC). In this paper, the hydro-elastic response of a bulge wave energy converter is examined by the implementation of a two-dimensional potential theory. The numerical implementation of the Frank Close-Fit method (FCFM) defines hydrodynamic coefficients and incident wave loads, where computation time is reduced with respect to the three-dimensional boundary element methods (BEM). These coefficients are included by a two-way coupling in the equation of motion for bending and bulging, which defines the interaction between incident waves, radiated waves and wall deformations. The results are compared to analytical and numerical methods and this analysis reveals that the addition of the FCFM to a modal analysis is valid to use for hydro-elastic problems in bulge wave energy converters.

The bulbous bow is a common feature for large displacement vessels. The purpose of the bulbous bow is to reduce the bow wave, hereby making use of wave cancellation theory. The main drawback of these type of bows is that the drag reduction effect is only present for a limited range of sailing speeds. If the transit velocity is altered, the effect of the bulbous bow can even result in an increase of wave making drag. Due to this sensitivity to the sailing speed it is important to be able to predict the location of the waves generated by the protruding bulb. Computational fluid dynamics is gaining interest in commercial marine industries. The size and transit velocity at which the previously mentioned vessels that employ the protruding bulb operate, results in the common use of Reynolds averaged Navier Stokes (RANS) models. To investigate the accuracy of these RANS models, a 2D model is presented in this thesis. The bulbous bow is modeled as a shallowly submerged 2D naca0012 hydrofoil. The justification for this simplification is that the geometry and flow over a bulbous bow is too complex for the duration of this project. A submerged 2D hydrofoil can still capture the important flow dynamics for free-surface waves. In this thesis we focused on evaluating the accuracy of RANS models for simulating the wave dynamics that arise when a shallowly submerged 2D naca0012 hydrofoil moves through water. The main objective is to find which geometrical and fluid dynamic properties have an effect on the free surface wave profile. Apart from questioning if these properties have an influence on the wave profile, we also want to know how the wave profile changes by altering these properties.
The interFoam package from OpenFoam was used for simulating the flow. InterFoam adopts the volume of fluid (VOF) approach proposed by Weller (Weller, 2008) for simulating multiphase flows. Turbulence modeling was done using the k-ωSST two equationmodel from Menter et al. (Menter, 1992). In 1983 Duncan and his colleagues published a paper on the free surface wave dynamics generated by a towed naca0012 hydrofoil (Duncan, 1983). The results from their experiments are used as a benchmark for the present study. From a single phase test we found that the experiments from Duncan where performed in the regime where transition of the boundary layer from laminar to turbulent is present. The presence of this transition is expected to be one of the reasons for the disagreement in literature on wave elevation, wavelength zero point crossings and lift and drag coefficients. It is shown that the relatively small gap between the basin floor and the hydrofoil of 0.86 chord lengths has a significant impact on the wave profile and the flow at the hydrofoil. Reynolds independence is found to be at Re ¸ 2•10⁵ for a towed hydrofoil submerged at h/c = 0.955 with the basin floor located 10 chord lengths below the hydrofoil. Below this value a reduction in Reynolds number results in an decrease of the wave amplitude and an increase in the wavelength. The assumption to neglect the resistance from the hydrofoil wake made by Duncan is shown to be false. The dominating dimensionless parameters for these types of flows are: Froude based on submergence Frh, Froude based on basin to foil height Fr_D and the Reynolds number based on the chord length and the bottom fluid parameters Rec . Note that in this thesis the angle of attack (α) has been kept constant at 5° which does
effect the flow but this has not been investigated during this research. A attempt is made to simulation breaking waves in the present model. The Breaker type in the present study differs from the one found by Duncan et al. (Duncan, 1983). Even if the same breaker type was found the elevation and wavelength differ a lot. It is therefore concluded that The present model is not suited for predicting
breaking waves.

In this thesis, it was examined how high-frequency operational data collected from an automated recording system, can be used to develop a vessel’s performance model. Both the traditional and the Machine Learning (ML) approach were examined. In the traditional approach, every component of the propulsion plant was examined separately, while empirical or semi-empirical methods were used for the added resistance due to waves, wind and shallow water. Historical data were used for verification and tuning (where needed) during the development of the model. In the Machine Learning approach, the method of Support Vector Machines was used. Also, it was examined whether a vessel’s performance model can be developed by combining the methods mentioned above. Thus, in total four models were developed. The data regarding the last year of operation of the vessel Schippersgracht were used (45000 data points) to test the models. It was found that with all the four models, 80 % of the examined dataset was calculated with an error of less than 10 %. The daily fuel consumption was calculated for the same dataset and for 90% of the days examined, the daily fuel consumption was calculated with an error of less than 10 %. The main conclusions about the developed performance models is that all the models resulted in more less the same accuracy. The model based on the traditional approach has the advantage that it offers more information and more outputs can be taken, compared to the ML approach which only provides the output of the fuel consumption. On the other hand, the model based on the ML approach is significantly faster and allows many iterations to be performed in a short time. Regarding the models which were developed by combining the approaches mentioned above, they did not result in additional advantages. Finally, two case studies were performed. In the first case study, it was presented how the model, developed following the traditional approach, can be used to examine how modifications in the propulsion system will influence the vessel’s fuel consumption. The case of switching from fixed rpm (that is currently used) to a variable rpm system was examined, which is a real scenario that the company is considering. It was calculated that installing the variable rpm system and a frequency converter will result in annual savings of around 250,000 € while the investment’s payback time is estimated to be around two years. In the second case study, a future voyage simulation algorithm was developed. This algorithm receives as inputs the voyage plan(route and speed) and performs a calculation for the voyage’s fuel consumption by taking into account the weather predictions. The voyage simulation algorithm is making use of the ML model. A few cases were examined in order to examine how many days in advance the calculation is reliable (due to the uncertainty of the weather predictions) and about the time interval that should be used in the algorithm. However, clear conclusions were not derived, and further examination is suggested(by examining more voyages).

A two-dimensional (2D) panel method is developed to find the first and second order wave forces acting on a semi-submerged cylinder in regular waves. The panel method is based on potential flow and the waves are modeled for both finite and infinite water depth. The motion is limited to heave, but allows for extensions to other modes as well. It uses boundary conditions for floating body dynamics with Neumann and mixed type boundaries on the surfaces. The waves are generated and the reflection of the waves is suppressed by generating absorbing boundary conditions (GABC) on the radiation surfaces. The model is used to investigate the hydrodynamics of an oscillating buoy wave energy converter (point energy converter). For this, an analytical solution of the optimal damping is used. The method uses panels along all boundaries to solve the boundary conditions. The model can be used for any time-harmonic free surface flow problem. A second order wave running through the domain is successfully modeled, without the interference of a body. Challenges of a second order model with body are explained. The boundary element method has innate challenges finding the correct solution to tangential flows on the panels and spatial derivatives of the velocity, which are required for the second order solutions.

The Defence Materiel Organisation found that using a design margin to estimate required space for logistic systems (e.g. staircases, hallways) during the concept exploration design phase is insufficient and impractical. A more educated estimation of required space for logistic systems is hard, because the configuration of systems is varied significantly. Indeed, the size and location of logistic systems are dependent on the location of functional systems, amongst others, which could be driven by logistic systems in turn. To solve this iterative problem, a novel Logistic Model was created and integrated in the TU Delft Packing approach. Based on a network representation of the ship's structural subdivision, a novel path finding and selection approach, initial positions of functional systems and upfront defined logistic relations between these functional systems, the size and location of logistic systems has been determined for and integrated in each concept design created by the TU Delft Packing approach. The logistic performance of the low detail designs was calculated by a novel Logistic Performance Measure and used to find logistically promising designs during concept exploration. Test cases indicated that the new method meets the research objectives.

The crises of global warming, air pollution, acid rain and the running out of oil make the investigation into alternative fuel technologies crucial. New technologies are being investigated on a global scale in an attempt to address these problems. This thesis investigates the use of hydrogen-diesel dual-fuel engines and fuel cells. The economic feasibility includes the comparison of these energy converters with more conventional alternatives. The storage of alternative fuels, the reforming of hydrogen carriers or the inclusion of carbon capture systems are some of the aspects considered in the analysis.

Harsh market conditions make optimising the performance in shipping more and more important. Shipping companies are becoming more and more data driven due to developments in data systems and these harsh market conditions. The goal of this research is to determine how and how much added value can be realised through shipping performance management with the help of a ship performance monitoring system within Spliethoff Group. This research continues after the development of the performance monitoring system. The demand or this research arrived from the fact that simply putting a performance monitoring system in place does not realise added value. Applying the knowledge creation from the performance monitoring system through well structured performance management is what realises the added value. Determining the methods and quantifying the potential results is what is done to realise the goal of this research.
During the research it is found that high data quality is of the utmost importance in order to accurately asses the performance of a vessel. A structured method for assessing the data collected by the performance monitoring is found and applied to the performance monitoring system as a verification. Data quality deficits such as the speed of the ETL processes, incorrect data blending and calculations are identified and corrected. This led to a near live, high quality data stream which can be used to asses and optimise the performance. Continual assessment and improvement of the data quality is recommended.
Suitable methods to analyse this data to create knowledge are determined. A form of hybrid modelling where simple theoretical models are fitted to the filtered data using regression is used to create baselines and give a clear overview of the effects of certain operational parameters on the performance of a vessel. These models can then also be used to increase the accuracy of tools such as the weather routing and voyage planning tool. Benchmarking between sister vessels or the baselines is seen as a good means to identify performance deficits. Visualising and analysing the data with the help of a BI tools is a good way to share the knowledge throughout the company.
The performance management in place at Spliethoff is assessed to form a baseline to improve upon. It became apparent that Spliethoff overall has a good idea how to optimise performance but it does not have the information or data needed to do so. Since there is no information about the gain in performance of certain tools they are not used correctly. Being able to show the performance gain from using these tools is an important benefit of the performance monitoring system. The communication and knowledge sharing throughout the company can also be improved with the use of the performance monitoring system. Poor follow up from upper management when performance deficits on top of this indicate that a lot of value can be created with an improved performance management plan which incorporates the performance monitoring system.
A new performance management plan based on ISO 50001 is proposed to realise this value. Due to the available data the management plan focuses on reducing fuel costs and optimising voyage planning.This is done by awareness creation through performance dashboards which also increase the information sharing between shore and vessel. A change in company culture to a more data based decision making and communicative culture is promoted and implemented through this plan.
To determine how much added value can be realised, the costs and value realisation potentials of the performance management system are specified. These are then used to determine the net present value of the performance management project for several scenarios. A large fleet and a small fleet implementation are researched. The total capital investment is either €543,000 when only the large consumers of the fleet are included (small fleet) or €1,310,000 when almost the entire fleet is included (large fleet). Only the direct monetary value is used to determine the net present value but indirect and non monetary values are also mentioned. The direct monetary value potentials are derived from operational cases where performance deficits have been identified. The resulting total added value (NPV) of the small fleet implementation ranges from €2,165,970 in a pessimistic scenario to €8,711,272 in an optimistic scenario after 11 years. €6,000,146 is the expected total added value realisation for the small fleet implementation after 11 years. For the large fleet the results are: €4,966,756 for the pessimistic scenario, €18,103,704 for the optimistic scenario and and expected added value of €12,805,994 after 12 years. Most scenarios have a pay back period of less than 2 years with the exception of the pessimistic scenario of the large fleet which has less than 3 years. All indirect and non monetary value is seen as a bonus on top of this meaning that there certainly is a lot of added value to be realised by implementing performance management which is supported by a performance monitoring system.

Due to the increased social importance and regulations on shipping emissions, effort must be made by shipowners, operators and naval architects to reduce the amount of air emissions from ships. A large set of emission control methods exists, but compatibility and interaction issues complicate their implementation. This thesis contains a decision-making method tailor-made to the case of Seatrade. The decision-making method makes a cost comparison of different emission compliance methods for an arbitrarily ship, making use of the NPV. Case studies are performed to get an indication of the promising emission compliance methods for the Seatrade fleet.