Stolt tankers is the largest operator of deep-sea chemical parcel tankers. Parcel tankers differentiate form bulk chemical tankers by the additional features that the ships have, such as cargo cooling, cargo heating, many (small) cargo tanks, highest level of chemical resistant materials and notation to carry the most dangerous chemicals. These features make the parcel tanker versatile compared to other tanker types, however this results in a higher cost. In the last twenty years, a shift has taken place in the deep-sea chemical shipping industry, driven by changes in regulations, funding of ships and macroeconomic factors. These changes have made the playing field of deep-sea chemical tankers more equal and commoditised, resulting in more competition by entries of new, privately funded companies with simple chemical tankers. Currently a large part of the parcel tanker fleet is nearing their end of lifetime and are expected to be recycled in the next five years. This creates the need to determine operating needs and requirements for replacements of Stolt Tankers’ ageing parcel tanker fleet. The goal of this study is twofold, first, is to determine the need for parcel tanker features in the market and, secondly, to determine the value that these features add. The findings have been concluded in terms of a priority for the feature in a new parcel tanker specification according to the MoSCoW prioritising technique.Analysis of the features is based on D37 parcel tanker class of Stolt Tankers. This typical parcel tanker class is a candidate for recycling in the next 5 years, and therefore a ideal study object for a replacement study. Four features were identified as giving the highest differentiation of a parcel tanker and are analysed in more detail: cargo cooling, cargo heating with thermal oil heating medium, small cargo tanks, and ship type 1notation. These features are analysed both qualitatively and qualitatively on its operation in the Stolt fleet, market demand and supply, competition and alternatives. The net added value of the features over the life of the ship has been calculated by means of a discounted cash flow analysis for base-,best and worst case scenarios.The cargo cooling feature yields the best added value for a new parcel tanker. The thermal oil cargo heating feature has a negative added net present value for only cargoes with this specific requirement. The study of the ship type notation has a low investment cost, however the loss of revenue by the capacity reduction is far more than potential revenues from thetype 1 cargoes. The number of cargo tanks has a large impact of the capital cost of the ship.Reducing the number of cargo tanks, i.e. the average tank size, yields a relatively large savingfor parcel tanker ship types. Combined with a decrease in the number of small cargoes, makes this a logical development for future parcel tankers. However, more research is required since there is a large discrepancy between the number of small cargoes on different trade routes.Based on the findings from the market and operational review of the D37 features the following priorities are given to the features. The cargo cooling system has been given a’Should Have’priority, the thermal oil cargo heating system has a’Could Have’and the ship type 1 notation a’Won’t Have’. Further research is recommended for the requirement of features of new ships with respect to the total fleet of Stolt Tankers. Secondly, modelling of cargo tank layouts with the statistical trading data is recommended to determine the requirements for the number and sizes ranges of cargo tanks

An important step in determining the performance of a commercial ship is to determine the vessel fuel consumption in offdesign conditions. In previous studies, the vessel fuel consumption is obtained using machine learning algorithms which use navigational data and meteorological data to train the models. Due to the inaccuracy of the weather hindcasts, the accuracy of these machine learning techniques is not satisfactory for Compagnie Maritime Belge (CMB) which is the company for which this study is performed. Since the vessel motions are a direct result of the meteorological conditions an approach is investigated in this research to replace the meteorological data by motion data to train a machine learning algorithm and obtain accurate results. The vessel motions are captured by a motion sensor on board the vessel. Multiple machine learning techniques were tested in this research. The data used to train the best performing learning algorithm represent the motions by the first and second moment of the nonderivative motion and the second moment of the first derived motion. These moments are obtained from the motion distributions of a time window of 5 minutes. The obtained best parameters for representing the motions were obtained by testing if a spectrum must be provided, how many motion derivatives are required, which moments are needed and how large the time window must be. Although the accuracy of the developed learning algorithm is determined as satisfied no digital twin could be made and tested. Unfortunately, due to the limited amount of data available no separate algorithm could be made which uses the Extra Tree learning, as digital twin base, to determine the overconsumption of the vessel. Only data from one voyage was available. All this data was used to train the learning algorithm to have as much variance as possible in the data set such that a good learning algorithm could be developed.

Deterministic predictions of wave induced ship motion are increasingly often used to enlarge the oper- ational envelope of ships that perform complex operations at open sea. The large amount of complex operations performed nowadays, motivates the relevance of motion predictions. The company Next Ocean provides these forecasts, based on linear seakeeping theory. While highly linear degrees of freedom are predicted accurately, roll motion predictions prove to be more demanding and are less accurate. This research aims to improve roll prediction accuracy by adding (non)linear damping to the equations of motion. The prediction optimization is performed on data of the platform supply vessel Acta Auriga. To enable the use of nonlinear forces, the equations of motions are first implemented in the time domain using Cummins’ equations. The linear coefficients in this equation are determined from the frequency dependent coefficients in Acta Auriga’s hydrodynamic database. To ensure the correctness and investigate the limitations of the implemented Cummins equation, the results from the time and frequency domain are extensively compared. Both monochromatic excitations, as well as spectrum (JONSWAP) excitations are considered. In contrast to linear force coefficients, nonlinear force coefficients are generally not known for a given vessel. Implementing these forces into the equations of motion imposes the need for an approximation of these coefficients. Estimates for the linear, quadratic and cubic viscous damping forces are made, using both the measured motions of a vessel operating at sea and the predictions of the corresponding excitation force, made by Next Ocean. A multivariate regression algorithm is used for the identification. The Cummins equation was successfully implemented. However, the translation from frequency to time domain was more error prone than anticipated; the frequency dependent coefficients need to meet requirements that are typically not met by databases meant for frequency domain calculations only. Furthermore, degrees of freedom without a restoring force showed running away behaviour that could not be negated without adding extra damping. The roll motion was susceptible to instabilities. The exact origin of this instability was looked for, but could not be found. Adding damping resolved the instability. Furthermore, the interpolation in the roll response amplitude operator introduced errors in the initialisation of time domain calculations, which led to inaccurate results when spectrum excitations corresponding to more severe sea states were used. Only under specific conditions, these high energy spectra led to accurate roll predictions. Adding damping made for a close match between frequency and time domain calculation for all degrees of freedom. The complexities mentioned made that an easily scalable algorithm could not be obtained using time domain calculations. Easy scalability be- ing important to Next Ocean means that running time domain simulations in Next Ocean’s product is deemed unrealistic. This also means that no nonlinear forces can be used in real time applications. In an attempt to improve linear predictions, coefficients in the linear seakeeping model, including the linear damping coefficient, are identified and vessel motions are re-predicted with the added damping and updated linear force coefficients, using the Cummins equation. None of the identified parameters led to better predictions than were obtained by Next Ocean. Identifying and updating parameters was therefore concluded to be not beneficial to the quality of the motion predictions. Adding a fixed amount of linear roll damping, which was not identified from the field data, did lead to improved prediction quality; correlations between predictions and measurements increased by 9.6%. While the motion prediction could not be improved using the Cummins equation, valuable information on the time domain simulations was obtained. The finding that better predictions were consistently obtained by adding a fixed amount of damping, sparks an opportunity for further research into the ideal amount of damping. This, and more elaborate identification schemes could provide meaningful insight to improve motion predictions.

The design of polar expedition cruise ship is not a trivial task to the naval architect due to the complex nature of the ship itself. Concept exploration are hereby required to improve the understanding of the design problem and identify its challenge as well as possible solutions. However, it is always difficult to generate the technically-feasible design solutions while still satisfying multiple and potentially conflicting performance criteria for the polar expedition cruise ship. There are currently two ways of optimizing the concept design: manual optimization and computer-optimization. The computer-based optimization, such as the Packing Approach developed by TU Delft, can semi-/automatically generate a set of design solutions. After the generation of these design solutions which are unknown in many performance behaviors, it is necessary to post-process them and increase the quality of those designs created from both optimization methods. Design rationale is an effective way to serve as qualitative metrics in post-processing the configuration layouts of the concept designs. However, the ambiguity and potential conflicting aspects within the design rationale are difficult to handle by the current post-processing method while fuzzy logic theory can be utilized to cope with the design problems involving subjective and ambiguity. Hence, it is proposed to develop a new methodology to better post-process the concept design of a polar expedition cruise ship.

Floating structures have developed significantly in recent years. As land is becoming scarce, the use the water surface will contribute to ease this scarcity. Therefore in recent years, floating structures covering large areas have been developed, also called flexible floating structures. In this project the focus is set on the mooring system very flexible floating structures (VFFS). At the TU Delft, two towing tanks can be used to investigate the mooring system of VFFS, however first a reliable measuring system is required that is able to examine a specific part of the mooring system. Conventional setups that measure the mooring forces consist of large instruments, as these instruments only have a small effect on their investigated structure (vessels). The response of VFFS is dominated by elastic deformations and differs from conventional rigid structures. For VFFS, these type of instruments will have a large effect on the structure motions and thus these conventional setups cannot be used. Therefore, a new measuring system is required to conduct small scale experiments with VFFS, and the following objective is formulated: Develop an instrumented mooring system for VFFS at model scale for the towing tank at the TU Delft and determine its accuracy. A new concept is developed in this project. This concept resulted from an extensive concept development where all functions of the system were analyzed. With the use of a Morphological Chart and a Multi Criteria Analysis the best concept was selected. For this concept, it was determined that the focus should be on the sensor configuration and calibration procedure. First, the optimal sensor configuration of the concept was specified by analysing the working principle of the concept. Second, the calibration procedure was further analyzed. From this analysis, three calibration procedures were developed: the single sensor calibration matrix, the full fixed calibration matrix and the full rotated calibration matrix. From literature and theory, it was not possible to determine in advance what calibration procedure should be selected, and therefore the performance of the procedures were verified with experiments. All calibration procedures were executed, whereafter the performance of the different procedures were compared. The two main considerations for the comparison were the accuracy and the usability of the procedures. After performing the comparison, the main conclusion was that the full upright calibration procedure is the optimal procedure. To verify the concept under realistic conditions, an example application was performed in the towing tank No.1 at the TU Delft. By doing this, the concept has proven to be suitable to measure the mooring force and transform them into usable data. In this project a new concept was developed into a working system. This system forms an excellent base for extensive research into the mooring system of VFFS, and is a good addition to the measurement instruments for the towing tank at the TU Delft. It is concluded that the system is able to measure the mooring forces and the direction. The accuracy of the system still has to be improved, and with additional research the working concept can be further developed.

Delft University of Technology has access to a towing tank where a wave maker can generate waves. When generating waves, non-linear start-up effects occur at the start of a wave train which affect the rest of the signal. The aim of this thesis is to develop a model which can take these effects into account. A numerical modelling approach is adopted, due to the necessity for generating a large space of wave profiles and the need to optimize towards a wave maker input given a wave profile. A clear assessment of the state-of-the-art revealed a scope of present methods to model non-linear free surface waves. A potential flow assumption proved a clear balance between accuracy versus computational cost. Analysis of this model showed that the state is described by a balance between potential and kinetic energy and should, in principle, be conserved. For numerical modelling, the Finite Element Method is adopted. The sparse matrices and ease of evaluation of the integrals allow for a better adaptation in present computer architectures. Additionally this method provides more rigorous mathematical tools to demonstrate properties such as stability and convergence. Lastly, the use of Isogeometric Analysis where the solution space is described by splines instead of polynomials could provide an advantage over conventional methods with respect to continuity, convergence and refinement strategies. Subsequently, literature revealed that the potential flow model in conjunction with FEM will result in model that is accurate, stable and fast. A novel numerical model is presented where the spatial discretization is done using IgA and the resulting semi-discrete Ordinary Differential Equation is integrated in time with a separate method. Analysis shows that this spatial model inhibits the same energy conservation laws as the physical model. Implementation is done in the DelFI, an in-house fixed domain Navier-Stokes solver with an Open Source back-end named MFEM which utilizes clever FEM abstractions and parallelization. To successfully implement the non-linear problem, first a linear problem is implemented to facilitate computation of variables that are defined on the domain only, in this work the free-surface elevation. This results in introducing an additional problem to compute the elevation on the interior which is dependent on the free-surface, but not vice-versa. This, to ensure the wave problem remains unaffected. Coincidentally, this definition of the free-surface elevation on the interior is used to deform the mesh required to capture non-linear effects in the time-dependent domain. Results of the linear problem show to agree with literature. Conservation of energy is guaranteed, yet conservation of mass can be attained with sufficient mesh and time resolutions. This affirms the successful implementation of free-surface problems in DelFI. Extension to the non-linear case shows that energy is not conserved, yet analysis shows it should. The same holds for conservation of mass. Still, both quantities can again be contained with sufficient mesh and time resolution. Additionally results demonstrate that implementation of a stabilization scheme is needed. Finally a benchmark case demonstrates that with the current limitations, results agree with others. This research demonstrated a novel mathematical framework to compute non-linear free surface waves with special emphasis on conservation laws and geometric compliance with the fluid through Isogeometric Analysis. A basis has been laid towards optimization of wave maker signals given a free-surface wave envelope.

During the early stages of ship design exploration, design freedom is abundant but problem knowledge is scarce and most costs are already committed. This amounts to an incentive to look at the influences of the requirements on a design, to better understand how a concept is defined. This thesis investigates the operational architecture concerning how systems are used (often in a temporal fashion). A way to quantify the operational architecture is with operability, which describes the ability of a ship to perform its mission. This thesis identified the system performance consisting of availability and vulnerability part of operability as its main topic. Markov theory was selected to assess the availability of systems in order to maximize the operability of a naval vessel. Transition rates of systems are a key element of Markov theory but are hard to obtain during Early Stage Ship Design. A network-theory-based approach allocated nonquantifiable focus points to each system to determine their importance within a network. These were then linked to transition rates, which are required for a Markov chain to calculate the availability of a system. Four case studies were performed to test the model: several configurations were compared, two different focus points approaches were used, different ranges of rates were applied, and systems were added or subtracted. The model proved to behave according to educated guesses beforehand but also gave new insights in connections between nodes. The eigenvector centrality approach used to allocate focus points was found to be better than the combined connectivity approach. The scale of the ranges of rates should not result in very high values for system availability since they do not provide data which makes comparisons between network configurations possible. Very low values of system availability were deemed too far off from real-life values. This thesis paves the road towards a total assessment of operability. It has focused on the availability of systems, and delivered a method to make preliminary decisions for systems design in the early stages.

Recently the interest in hydrofoil vessels using a fully submerged hydrofoil increased. Hydrofoil vessels experience a resistance hump and possible instabilities during their takeoff of which both are influence by waves. In order to determine the required power during the takeoff to overcome the resistance hump and to investigate whether the hydrofoil vessel is stable during the takeoff numerical simulations or experiments have to be performed. Experiments covering the full takeoff require a long towing tank and high towing velocities and therefore these experiments are costly. The alternative, performing numerical simulations, is favorable but requires a suitable numerical code. As no validated code is available in which a takeoff can be performed in waves, in this research Panship, a potential flow code suitable for high speed craft and adapted for use with hydrofoil craft, is validated for the takeoff of a hydrofoil vessel. In this research the results of Panship are compared with results of experiments and other numerical codes in four different stage as little validation data is present for the takeoff of a hydrofoil vessel. The four different stages are: a foil without the influence of the free surface, a foil with the influence of the free surface, two foils with the influence of the free surface and the hull and foil system near during the takeoff. In these four stages the lift and drag determined in Panship is compared with available experimental results and numerical codes. As the simulations in Panship require a vast amount of input parameters, the influence of these parameters is studied first to ensure the reliability of the results. Comparing the results of Panship for a deeply submerged foil with another potential flow solver shows that the lift is predicted correctly, but that the induced drag is underpredicted. If viscous effects are required in the solution, the quality of the results of Panship is dependent on the type of hydrofoil used. As some foils have a large viscous effect on lift, the lack of viscosity on Panship, leads to a low quality of the results for lift and induced drag as they are overpredicted. The trends for interaction of a foil with the free surface are predicted correctly but the underprediction of induced drag influences the quality of the results. Panship is able to predict the effects of foil interaction for lift correctly, but the results for foil interaction for drag are poorer. During the takeoff Panship is able to predict the lift fairly correct but the total drag is underpredicted severely. Recommendations are given to improve the results of Panship and for future work.

Wind-assisted ships are installed with wind propulsors capable of generating thrust for aiding the propulsion of the ship, with the purpose of saving fuel by reducing the required propeller speed and thus engine power. Wind-assisted ships are becoming more common due to high fuel prices and rising environmental concerns. The subject of this thesis is wind-assisted ship maneuverability, which is a relatively new and unexplored topic. There are many factors which this study can involve, and so the goal of this thesis is to study the general behavior of wind-assisted ships during the Turning Circle and Zig-Zag standard maneuvers, and investigate in depth the effect of different control optimization schemes for the wind propulsors. This study requires building a 4 degree-of-freedom (DOF) time domain maneuvering model in which the equations of motions for a wind-assisted ship are solved and the required parameters are input in order to execute the standard maneuvers. The model includes calculation of all the major forces on the ship, including hydrodynamic forces common among maneuvering models, and with the addition of aerodynamic forces due to the wind propulsors. Once the model is built and shows sufficient accuracy, the maneuvers are simulated for a variety of wind conditions, sail configurations, and wind propulsor trim optimization schemes. The behavior of the ship due to these different conditions and the compliance with maneuvering standards are discussed. The results of the simulations show that the maneuvering behavior of the ship is indeed significantly dependant on the wind, and also how the wind propulsors are controlled. Based on the results, in general, the ship shows the behavior to turn quickly into the wind and slowly while turning against the wind. The effect this has on the maneuvers is that the Turning Circle is generally tighter when the initial turn is turning toward the wind, and larger when the ship is initially turning away from the wind. For the Zig-Zag maneuvers, the ship is alternating in turning toward and away from the wind and so the behavior of turning faster toward the wind is evident in the measured quantities of the Zig-Zag maneuver. The standardized requirements on maneuvering do not yet have considerations for wind-assisted ships and thus it is unknown what will be allowed in the future in terms of wind propulsor control during the standardized tests. Additionally, the abilities of the ships and wind propulsors when it comes to active optimization and wind propulsor trimming are not well known. Thus in this thesis a variety of options for wind propulsor control are studied in order to provide some insight on what is possible, covering some more conservative and more aggressive approaches. The wind propulsor optimization shows to have a big effect on the ship maneuverability, and with thoughtfully constructed optimization schemes there is a general improvement in the measured quantities that result from the maneuvers.

Currently there are three methods of calculating the Dynamic Positioning capability of a vessel namely: static calculations, real-time time domain simulations and fast-time time domain simulations, although the outcome of the last two should be identical. In each of these methods a set of input variables is required to perform the calculations. These inputs are not always exactly known and are therefore sometimes estimated or taken from databases. It is not always clear how big the uncertainty in these estimated inputs is, and on top of that: how big the effect on the predicted DP capability is. To be able to quantify how certain a DP capability calculation is and which input data contribute most to the output uncertainty, in this thesis the input uncertainties for both static and fast-time dynamic calculations are investigated. Each method is subdivided in three different design stages which are: conceptual design, preliminary design and as built design. For the static calculations all three design stages are evaluated but for the fast-time dynamic simulations only the as built stage is considered. The static calculation part of the analysis consists of determining the input uncertainties, the input sensitivities to the output and finally calculating the output uncertainty. The method used for this calculation assumes that either the relation between input and output is linear or can be linearised at the point of interest. The input uncertainties are calculated using historical data of the Bibby Wavemaster 1 which is the vessel used as case study throughout this thesis and is specifically designed for the purpose of servicing offshore wind farms. It is observed that the input uncertainties of the main dimensions of the vessel are clearly reducing when moving through the design stages. Furthermore it is concluded that the environmental coefficients of wind, waves and current are the most uncertain, even in the conceptual design stage where input parameters of the main dimensions of the vessel vary the most. When considering the sensitivity in the three design stages no big changes were observed, meaning that in all design stages the main dimensions of the vessel are most sensitive to the output. Finally the uncertainty in the output was evaluated were it was observed that for the as built stage still a standard deviation of 4% uncertainty of the output is present, resulting in a calculated 99.7% confidence interval of either 12% too high or too low. In the dynamic calculation part only the as built stage is considered. Again the uncertain parameters are defined but due to the PID controller in the dynamic model some new input parameters are now present. The gains of this PID controller are assumed to be uncertain and are therefore taken into account during the dynamic uncertainty analysis. Due to a limitation in the aNySIM licence bought by Damen it is impossible to change the wave coefficients which causes their uncertainty not to be taken into account. Since the dynamic simulations are considered to have strong non linearities and possibly even discontinuities due to thruster saturation, the calculation method used for the static part is not applicable anymore. Therefore it is decided to use Monte Carlo simulations to quantify the uncertainty in dynamic DP calculations. Due to the large computational time required to perform large amounts of Monte Carlo simulations with aNySIM, a machine learning method is used to capture the dynamic behaviour of the vessel. A small number of simulations performed by aNySIM is required to train the model which are selected using the Sobol design of experiments technique. This technique optimises the choice of the simulation points to make sure the complete space of possible inputs is covered. By using the machine learning model to obtain an output of a dynamic simulation only a fraction of a second is required instead of 17 minutes when using aNySIM. By running the Monte Carlo simulation on the created machine learning model it was observed that the 97.7% confidence interval for offset can either be calculated up to 8.7% too low or too high whereas the prediction for heading up to 23.1% too low or too high when compared to the base case. It is concluded that using DP for the purpose of people transferring by means of a "Walk To Work" bridge, uncertainties should be taken into account to reduce both safety and contractual requirements risks.

In the port of Ostend a discharge sluice is going to be constructed as part of an enforced dike ring. The proposed location of this discharge sluice is close to an already existing marina, the Royal Yachtclub Oostende (RYCO), and hindrance is expected regarding the outflow of the sluice in marina direction. When designing the sluice, an optimal balance has to be found between acceptable flow velocities in the downstream area and the capacity of the discharge sluice. It is therefore very important to be able to determine resulting flow patterns. Formulas and rules of thumb found in literature are not sufficient to determine the resulting flow pattern of this system due to the complex geometry, including a pile row for flow velocity reduction. Other studies have shown that numerical models could simulate flow patterns of discharge sluices with much detail. However, a lot of detail in the results also requires much computational time. An example of a detailed numerical software program that is able to simulate the complete three-dimensional flow field is COMSOL Multiphysics 5.6 (COMSOL). Although it provides the most detail, simulating the flow in the entire area of interest (including the RYCO) for a complete tidal cycle in COMSOL would take too much computational time. The objective of the present study is therefore to investigate the possibilities of determining the flow pattern downstream of a discharge sluice using a numerical method that requires less computational time but has sufficient accuracy to determine the potential impact of a discharge sluice on nautical activities. In the present study, two options are considered to determine the flow field downstream of a discharge sluice. Method COMSOL-D3D is a coupled numerical method of a COMSOL and a coarser Delft3D-FLOW 4 (D3D) model. The other option, method D3D, uses only a D3D model and the sluice outflow is schematized by means of the general discharge relation. As validation of the results is not possible due to a lack of measurement data, the methods are applied to a simplified case. The flow pattern resulting from each method is compared to the results obtained with a so-called baseline method. This method consists of modelling the entire domain with only a detailed numerical model, COMSOL. This is possible since, for validation purpose, the domain of the simplified case is relatively small and only stationary conditions are considered. In conclusion, there is a lot of potential in the use of both methods in predicting the flow pattern downstream of a discharge sluice. They produce for the simplified case flow patterns similar to those obtained with the detailed method. Moreover, both methods require relatively little computational time compared to a full 3D simulation, method D3D requires the least amount. However, there are a number of conditions for the application of both methods. The methods cannot be applied in the direct vicinity of the discharge sluice where the flow is highly three-dimensional. If one is interested in the flow in the first meters after the outflow opening or around the pile row, for example for designing the bottom protection, the two considered options are not sufficiently accurate. The flow in this area is too complex to simulate in a D3D model. In this case it is recommended to model the situation completely in COMSOL or a model similar to COMSOL. Furthermore, method D3D can only be applied if the sluice system is simple enough to correctly determine the discharge coefficient analytically/empirically and to simulate the effect of the pile row with a simplification in D3D. It is possible to accurately determine the effect of the pile row on the flow in this study with a schematized porous plate in D3D. Further research must show whether this applies to all types of pile rows. For method COMSOL-D3D it is important that a correct coupling is made between both models. Here it is important to gradually impose the flow rates in the D3D model. Furthermore, the coupling should be made before the predicted point at which the jets starts deflecting towards the side but downstream of the area at which three-dimensional flows caused by the pile row are present. It is important to note that due to a lack of validation data there is an uncertainty in the results following from the model approaches. Further research and the use of validation data must show how accurate the results of the considered methods are. In this research method D3D is applied to the Ostend case. It becomes clear that flow rates exceed predetermined limits for safe operation in the marina. This applies to the entire marina and a large part of the time that the discharge sluice is discharging in marina direction. Measures will therefore have to be taken to prevent this. It is recommended to use method COMSOL-D3D to investigate the optimization between flow velocities in the marina and the discharge capacity. This is due to the fact that the design of the discharge sluice is expected to become much more complex and as a result the discharge coefficient is no longer easy to determine using formulas from literature.

In the early 00 of this century, Keuning et al. (2007) looked into the hydrodynamic forces on the rudder and the influence of the hull and keel on these forces. Among others, they have assessed the lift and drag forces on the rudder. One of the outcomes of this study was an asymmetric lift curve; for negative rudder angles the rudder seems to stall at angles more than five degrees smaller than for the positive rudder angles. The goal for this research is to find and clarify the physical phenomenon which induces the rudder to stall at smaller rudder angles when subjected to a negative rudder angle (during bearing away). The main question to be answered in this report is: What physical phenomenon is at the basis of the asymmetric stalling behaviour on the rudder of a sailing yacht? Towing tank tests are used to validate the data from Keuning et al. (2007). After which RANS CFD simulations are conducted in NUMECA to compare the towing tank tests to and to visualise the wake of the yacht in attempt to clarify the phenomena found. A number of conclusions were found in this study. Firstly, the results of the towing tank experiments showed similarities to the previous experiments by Keuning et al. (2007). Differences are found in stall angles for positive rudder angles. These differences raise questions on the correctness of either of the experiments. Secondly, no reasonable explanation is found for the negative drag forces found in the towing tank experiments. It is expected that these originate from the set-up of the rudder. Thirdly, the lift curve found in the experiments is confirmed by the CFD data for the test cases. The physical effect behind the early stall behaviour of the rudder is still unknown. It is indicated that a part of the decrease in stall angle, a couple of degrees, is caused by the influence of the keel, when the disturbance passes on the low pressure side of the rudder. The hull is responsible for the remaining decrease. The CFD data indicates an influence of the vorticity of the keel and the boundary of the hull to cause a disturbance on the rudder. Further research in necessary to clarify the results found in this study.

Two important performance parameters of a ship are fuel consumption and motions in a seaway. Besides a well-designed hull, several appendages can be used to increase the performance. One of these is a resistance reducing fixed foil behind the transom of the ship. This wing has the potential to create large lift forces near the aft of the ship, thereby changing the resistance and dynamic position of the vessel. In this thesis an algorithm is designed that controls the pitch angle and thus lift of this foil. The goal is to investigate the potential of such a dynamic foil for further reduction of (added) resistance and ship motions. The resistance reduction is investigated by creating thrust on the foil trough an oscillating foil principle (i.e. vertically moving the foil to create propulsion). The research is done with the use of the FINE/Marine CFD package. A model from the AMECRC OPV series is used for analysis, in combination with a foil optimized in earlier research. From the literature review can be concluded that a dynamic, rotating foil behind a ship will not generate thrust in the same manner as an oscillating foil does. Furthermore, an initial CFD study showed that the pitching velocity of the ship has the greatest influence on the changing angle of attack on the foil. Additionally a study into basic wing theory showed that the foil would produce the most thrust at low angles of attack. With the use of this information, four algorithms were developed. Two of these algorithms focused on reducing the overall resistance by increasing the generated thrust on the foil. The results showed that the generated thrust cannot be significantly increased in comparison to a static foil. Two other algorithms were designed with the goal to reduce the pitching motion of the vessel. These two algorithms both achieved a significant reduction of the pitching motion, which also lead to a reduction in added wave resistance. Although the foil dampened the pitch motion, the generated thrust was found to be less than for the case with a static foil. The reduction in thrust was similar in size to the reduction in added wave resistance. It can be concluded that the rotating foil was able to provide similar resistance reduction as a static foil, with the added benefit of a significant reduction in pitch motion.

Accurately predicting the ship motions, is essential knowledge when operating in water. To predict the ship motions, multiple ship characteristics have to be known. For the roll motion, one of these characteristics is the roll damping coefficient. Nowadays the industry standard to determine the roll damping coefficient of a ship is by performing model tests or using empirical formulas created in the late ’70s. In recent years computational power has increased significantly. This increasemakes it possible to start using computational fluid dynamics (CFD) for practical purposes instead of solely scientific research. The roll damping coefficient is a very interesting parameter to examine with viscous flow solvers as the roll motion is heavily influenced by the viscosity of the water. Multiple studies have been performed with 3D and 2D CFD simulations. By simplifying the simulation to 2D, calculation time is reduced drastically. This simplification is performed by only simulating one cross-section of the midship. Only simulating one cross-section causes a loss of accuracy in how well the roll damping coefficients can be determined as the damping effects of the bow and stern are not taken into account, or are roughly estimated. During this research, a method to accurately determine the roll damping coefficients of a ship, while maintaining low computation time, is investigated. This method is based on performing multiple 2D CFD simulations of different cross-sections and combining the results to capture the behaviour of the entire ship. With this approach, the high accuracy of 3D simulations and the low computation time of 2D simulations are combined. The accuracy of this 2D section method is determined by comparing the results with experimental data. The experimental data is obtained through free roll decay tests of a ship from Van Oord on model scale. A 3D CFD model, which simulates a free roll decay test, is created using OpenFOAM. The results of this simulation are compared to the experimental data to determine how well a 3D simulation can predict the roll damping coefficients. Next, a 2D CFD model is created using OpenFOAM which is validated using experimental data of a structure which has a uniform cross-section along the entire length. Lastly, the validated 2D CFD model is used for the 2D section method. Multiple cross-sections of the same ship from which the experimental data is obtained and with which the 3D CFD simulation is performed, are simulated. The results of the 2D section method are compared to the experimental results in order to determine how well this method can determine the roll damping coefficient of a ship. The simulation of the 3D free roll decay test underestimated the linear damping. The non-linear damping was within the margins of the experimental data. The 2D forced oscillation simulations showed an excellent agreement in linear and non-linear damping with both the experimental data as with a comparable CFD simulation. The 2D section method slightly overestimates both the linear and non-linear damping of an entire ship but overall this method shows promising results. However, more research should be done to optimise the method further.

The international maritime sector accounts for about 2% of all global carbon dioxide (CO2) emissions, the main greenhouse gas that causes global warming. Nations meeting at the United Nations International Maritime Organization (IMO) in London have proposed an initial strategy for the reduction of greenhouse gas (GHG) emissions from ships, setting out to reduce GHG emissions from international shipping by phasing them out as soon as possible with the aim to achieve zero emission by the end of this century. Heerema Marine Contractors (HMC) is a world leading marine contractor in the international offshore energy industry and aims to be a role model in environmental responsibility through carbon emission reductions. As a result of HMC’s global activities, their fleet covers a considerable distance through transit across the globe. Their large semi-submersible crane vessels are conventionally transported through towing by a tug. The great amounts of fuel required for these transits provides a significant opportunity for the reduction of HMC’s carbon footprint. One such initiative proposed within HMC is the application of wind-assisted ship propulsion on the tow configuration. This report presents an initial investigation of the feasibility of wind-assisted towing of the HMC’s Thialf, a semi-submersible crane vessel. Previous internal research at HMC showed the feasibility of using a discarded Panamax vessel as a floating breakwater. While operationally the discarded Panamax was found to be feasible, economically this was not the case. In this research, using the Panamax as a wind-assisted tug for towing the Thialf is investigated. As such the Panamax vessel can be employed for multiple purposes; for wind-assisted towing and as a floating breakwater, improving the financial feasibility. To test the performance of a wind-assisted tow operation, a comprehensive 2D model is developed in this research to be able to check configuration variations in a wind-assisted tow setup. A conceptual design of a Panamax vessel converted into a sailing tug is implemented in a 2D model simulation. The performance in combination with the Thialf is assessed under the common environmental conditions experienced by the Thialf for various transit routes. Results showed that the use of a wind-assisted tow configuration based on a Panamax, without using the Thialf propulsion is not feasible. The main point of failure is the required force balance transverse to the sailing direction. The Panamax basis used for the preliminary wind- assisted tug design proved to be not the optimal base case due to the limited leeward force generation under a drift angle and the large sensitivity to environmental loading. Although implemented measures improved the systems performance, it is debatable whether a wind- assisted tow configuration with the associated uncertainties is the most promising area to accomplish significant CO2 reductions.

The electricity demand increases globally and requires a shift toward renewable sources to prevent the exhaustion of the planet. The shipping industry is responsible for 2-3 % of the global Greenhouse Gas emissions and Heerema Marine Contractors (HMC) identified floating solar as a promising solution to reduce the emissions, of their crane vessel Sleipnir, during operations. This study is the starting point of a technical feasibility study as a temporary energy supply for Sleipnir. The design is strongly focused on the temporary deployment and limited occupied deckspace during transit. Current floating solar systems are commonly designed for permanent deployment as supporting structure for rigid glass photovoltaic (PV) panels. Furthermore, modular constructions are used to limit the transportation costs however they are not designed for temporary deployment. A new PV innovation is flexible lightweight films which allow a more flexible supporting structure. A flexible thin sheet can be spooled on a drum to make temporary deployment possible. The influence of the wave loading on the coupled hydrodynamic behaviour is evaluated since wind and current loading are predictable based on previous research. The structural design parameters of the thin sheet and drum are designed to mimic the excitation motion since wave structure interaction has been minimized to reduce the mooring force. Therefore, the draft must be low and the characteristic length related to the bending stiffness of the sheet should be smaller than the excitation wavelength. The draft of the drum should be low to have a natural heave frequency higher than the excitation frequency. The coupled hydrodynamic response for head loading is evaluated with model tests in a towing tank. The concept is scaled according to Froude to ensure the surface waves, which are gravity-driven, are properly scaled. Regular waves are chosen based on the workability wave spectrum of Sleipnir. The roll and heave response over the frequency domain is indicated by analyzing the stable response at certain frequencies. The motions of the drum are obtained with the use of object tracking based on video recordings. The force within the connection of the system was measured with a force transducer whereas the mooring force was measured with a newly developed 3D-sensor. It turns out that the heave motion of the system mimics the excitation motion over the wavelengths resulting in small drift forces. Significant rotations of the drum were observed for the longer wavelengths leading to water pumping over the sheet. The overturning moment is driven by the dynamic pressure over the drum diameter and the measured force in the connection generates a counteracting moment. The connection force is proportional to the buoyancy required to submerge the sheet and the acceleration of the free-floating sheet. The feasibility of an OFPV concept for Sleipnir is demonstrated but the rotations have to be reduced by lowering the natural roll frequency. The drum dominates the coupled hydrodynamic behaviour compared to the sheet. Either the dimensions of the drum should be lowered or the thickness of the sheet must be increased. Decreasing the drum diameter is favourable over a thicker sheet since that would increase the characteristic length. Another option is to adjust the geometry of the drum to a shape where increased water displacement is required for the roll motion.

In order to meet the shipping industry's emissions reduction goals, it is imperative to explore and adopt alternative marine fuels. Methanol (or methyl alcohol) is expected to play a large role in the future. However, current regulations limit the attractiveness of methanol as marine fuel due to the inability to use the space around a venting point on deck. Hazardous area zones are installed around fuel tank vapour outlets due to the flammability and toxicity of methanol vapour. Consequently, these areas become very impractical. This thesis investigates the ventilation of the fuel tank vapour below the waterline instead on deck in order to be able to limit/eliminate these areas. Therefore, the main research question is: "What is the concentration of methanol at deck level when methanol is vented below the waterline?" An Eulerian based CFD model and a simple integral model are used to predict the methanol concentration above the waterline. The integral model predicts the gas concentration above the waterline based on the gas flow rate reaching the surface and the radial inflow rate of air. The CFD model tracks parcels (group of bubbles with the same properties) using the force balance in the discrete phase model. Both of the models are successfully validated against experimental data from the "Rotvoll experiment" wherein methane was released at the bottom of a water basin. The CFD model showed strong superiority over the integral model, o.a. due to the lack of gas dissolution in the integral model. The numerical models are applied to the case wherein a mixture of methanol and nitrogen is vented due to an overpressure. The overpressure could be caused by for example the failure of the vapour return line when bunkering or a fire. The bunker tanks are protected by a pressure relief valve, which reduces the overpressure by directing the gases in the bunker tank towards the venting location below the waterline. The flow rate characteristic (pressure - flow rate) of the pressure relief valve determines the rate at which the gases are injected in the water. The gas dissolution showed strong dependence on the departure bubble diameter and the venting depth. Different cases with different initial bubble sizes and different venting depths were simulated. The CFD model showed that in the most critical case (lowest venting depth 0.5m and largest initial bubble size 0.08m) the gas dissolution is large enough such that no methanol vapour reaches the deck of the ship and barge. The subsea venting of methanol-nitrogen vapour proved to be a safe alternative compared to the venting above deck.

Constructing the general arrangement of a ship tends to be a very complex naval architectural problem. There are multiple systems that all work integrally. Some of these systems need to be placed together, others need to be separated and some systems probably need to be both at the same time for different objectives. The preliminary ship design phase is all about finding the balance between these objectives and possibilities within the arrangement. Automated general arrangement generation methods, such as the TU Delft pack- ing approach and IECEM, have created an algorithm and methodology that are able to generate thousands of feasible ship designs corresponding to the desired requirements. These approaches combine a bin-packing and a genetic algorithm in order to create a diverse set of possible designs. Although optimisation approaches can efficiently generate and search for a set of designs, it can not automatically select a design, van Oers et al. (2008). Out of the cloud of generated designs, choosing and evaluating those designs that are of most interest seems to be a more difficult task, DeNucci et al. (2008). Human rationale deems necessary to decide what properties of an arrangement can be analysed as “good” or “bad”. Using computational force to assist with design selection based on qualitative properties needs a way of capturing this rationale, which is demon- strated by DeNucci. Subsequently, this captured knowledge needs to be applied in a methodology to actually analyse the data by this rationale. Design selection of computer generated arrangements is currently based upon performance parameters fo- cusing on numerical characteristics of the designs. Spatial relations within the interior layout can now only be manually analysed, which is merely possible for a singular design. This results in a lack of understanding of spatial and physical relationships, or qualitative properties, within the designed arrangement. This thesis proposes a method that is able to quantitatively compare these qualitative properties by creating a measure of effectiveness of the interior layout, or arrangement, of the designs. This is done by creating a simplified representation of the 3D arrangements using network theory. By converting system objects and connections of these systems into nodes and edges, a mathematical net- work description of the arrangement is possible. Using eigenvector and betweenness centrality measures, rank and weights are given to these system objects. Design rules based upon rationale captured by DeNucci are set up and used to analyse connections between these systems. A scoring algorithm is created that is able to combine the ranks of the systems with the captured rationale to give a singular performance parameter, or measure of effectiveness of the interior layout characteristics of the designs. Application of this method to a data set of small cruise ship designs shows the capabilities of this methodology and the ability to quantita- tively compare the qualitative properties of these designs. A data set of over 20,000 cruise ship designs created by the TU Delft packing approach is analysed by the use of the method. This demonstrates that the proposed method can be used on an entire data set allowing design selection based on the quality of the provided arrangements. The proposed method can be used to filter the data set of those arrangements whose quality seems to be too poor to be taken into account in design selection. Having these arrangements in the data set is still necessary, as this allows the genetic algorithm to create enough diversity within the design space. The proposed method can find specific physical properties of the arrangements and should lead to improved design space exploration of layout features of the generated designs. Capturing the quality of the design into a single measure of effectiveness brings problems as well. It allows the possibility of direct comparison of a large number of designs, but does not relate back to why designs score differently. Splitting design rules into different design objective scores, and possibly summing this later, could allow the designer to relate back to the design rationale and why a design scores better or worse. This would lead to more understanding of possibilities and problems within the proposed arrangements.

At the moment, offshore wind is an indispensable source of energy. Compared to onshore wind, wind speeds offshore are considerably higher and more constant. Furthermore, offshore wind turbines reduce noise and visual impacts. In contrast to fixed bottom foundations, floating wind can be economically feasible in global offshore waters that exceed a depth of 60 meters. However, floating wind has its challenges. Research has shown that the interaction between floater motions and wind turbine controller can be significant, especially above rated wind speed. The interaction between the hydrodynamics and aerodynamics above rated wind speed is the main reason why fully coupled aero-hydro-servo-elastic simulations are needed to determine the motions and mooring loads of the system. The downside of fully coupled simulations is, next to the need of comprehensive technical background, the high computational time which makes these simulations unsuitable for concept design studies. The purpose of the research is to developed a fast and simplified model that can be used for design iterations in concept design stages of Floating Offshore Wind Turbines (FOWTs). The simplified model must be able to predict the general motions and mooring loads with acceptable accuracy. Moreover, the simplified model should be based upon available wind turbine input data in an early design phase. A sensitivity analysis is carried out to determine the contribution of various physical phenomena, present in fully coupled aero-hydro-servo-elastic simulations, on the motions and mooring loads of the GustoMSC Tri-Floater with a 5MW NREL wind turbine located at its center. The fully coupled simulations are performed with aNySIM-Phatas. By this analysis, the main physical contributors to the motions and mooring loads of the GustoMSC Tri-Floater are selected to include in the simplified model. It is confirmed that the interaction between the aerodynamics and hydrodynamics is significant, especially for platform pitch motions in the above rated conditions. Furthermore, the (controlled) aerodynamic thrust calculated from Blade Element Momentum (BEM) theory, as well as the wind drag loads are found to be the main driving forces on the system. The simplified model is constructed by coupling an external Python code to the multi-body time-domain software aNySIM. Whereas aNySIM is responsible for the hydrodynamic and mooring calculations, Python is used for the simplified aerodynamic calculations. The effect of the wind turbine controller on the aerodynamic thrust is included by the use of the steady state thrust curve, aerodynamic damping ratios and filter on the incoming turbulent wind. The simplified model is compared with fully coupled aNySIM-Phatas simulations. Compared to fully coupled simulations, obtained results suggest that in a free floating condition the differences in the mean are found to be within 5% and 10% for platform surge and platform pitch, respectively. The mean and maximum differences in the forward fairlead tension were found to be within 2% and 5%, respectively. Moreover, the results show that the simplified model is 5 times faster and much easier to construct compared to the fully coupled simulations. The results of this research are encouraging as the simplified model can serve as a tool to predict the general motions and mooring loads with acceptable accuracy. Also, as Python is not coupled to aNySIM before to the best of the authors knowledge, this coupling opens doors to other simplified modelling strategies.