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.

Allseas Engineering B.V. is an offshore contractor, focussed on offshore pipeline installation. Since the late 80's, Allseas has been working on the design and construction of the Pioneering Spirit, a heavy lift vessel designed for the single-lift installation and removal of offshore topsides. From 2019, it is scheduled to be able to single-lift install or remove jackets with the jacket lift system.

The jacket lift system is located at the aft of the vessel and consists of two 170 meter tilting lift beams, hinged around the stern. During a jacket removal, the jacket is cut-off at the bottom, hoisted from the tip of the beams, partially rotated, and then tilted inboard. In between the hoisting and tilting is the transition phase. At the interface between jacket and the tilting lift beams, jacket support structures are located. In this thesis, the behaviour of the free-hanging of the jacket and the loads on these support structures due to the mating with the jacket are researched.

Jacket removal operations will take place in open sea and are thus subjected to environmental actions. The jacket, suspended from the tip of the beams, is excited due to fluid acceleration and velocity causing inertia forces and predominantly drag forces on the slender members of the jacket, as well as the excitation of the vessel through the suspension point. These motions are calculated with two different approaches. A direct-time domain model is developed of the jacket as submerged pendulum. To accelerate model simulations, the jacket is modelled as one single cylinder with different equivalent diameters to account for the total of drag and inertia. The second model is a full geometrical time-domain model simulation in AQWA.

In the design sea state, simulations showed that the most probable maximum momentum of the jacket due to environmental excitation is 4.5 106 kg m/s, and the motions of the centre of gravity of the jacket are all within a range of 1 meter, for the single and double pendulum and the full model. The influence of the environmental actions on motions of the structure is concluded to be small. This suggest that the jacket mating loads are governed by the tilting velocity of the tilting lift beams and the motion of its tip. The jacket mating simulations are done in the full AQWA model approach.

Fenders are modelled to absorb energy during the jacket mating. A sensitivity analysis showed that the parameters that have most influence on the mating phase characteristics are the tilting velocity and the stiffness of the fender. From still water conditions it seems that by increasing or decreasing the tilting velocity, this can affect the number of re-bounces and the maximum deflection. With increasing sea state, the duration and intensity of the mating phase increases. The fender deflection will increase for increasing significant wave height. The wave period does not have a significant influence on the maximum fender force. The amount of re-bounces reduces significantly for higher damping coefficients, while its influence on maximum deflection decreases.

The maximum force on the jacket support structures caused by the static gravitational force by the jacket once it is fully tilted is approximately 10 times higher than the maximum occurring force exerted on one of the fenders. Therefore, this static gravitational force is critical for the design of the jacket support structure, not the force caused by the mating.

Crew of small fast ships often experience exces- sive vertical accelerations when sailing in waves, leading to discomfort and injuries. In an attempt to avoid this, in good visibility experienced operators reduce speed voluntarily when they anticipate that the next vertical peak acceleration will be unacceptably large. However, at night and during excessive spray, the operator can hardly see the environment which makes it almost impossible to anticipate wave driven events. On top of that, this approach carries the risk of operator misjudgment due to loss of concentration or fatigue. In this paper, the potential of haptic feedback to support the operator in preventing dangerously large vertical accelerations is inves- tigated. A stochastic based approach was used in combination with a high end ship simulator to construct a haptic algorithm which gives a maximum advisable propeller speed setting based on an estimate of the current sea state. In order to test the effectiveness of this approach, a human-in-the-loop experiment was conducted using a within-subject design with 24 conveniently sampled participants. In this experiment the effect of haptic assistance is compared to manual control under both good and reduced visibility conditions. A key advantage of implemented haptic feedback algorithms is that the human remains in the control loop and can continuously decide to overrule the haptic advice. From the experiment it is found that the workload experienced by the operators is significantly decreased when using haptic feedback. However, no significant decrease in the number of excessive vertical accelerations was found using the current setup. A possible explanation for this result is the lack of motion cues and the inexperience of the participants. Therefore, it is recommended to extend the setup with a motion platform and conduct future experiments with experienced operators.

New floating wind turbine designs are needed to reduce production costs and to increase mass production feasibility. The TetraSpar floating wind turbine achieves these goals by being constructed using components highly suitable for standardization and industrialization. The design makes use of a suspended submerged counter weight to obtain a low center of gravity for the floating system, while also allowing a low draft during transport and installation. An analytic analysis of the counter weight suspension system is presented that investigates the behavior of the system. The main concern of the novel system is its motion relative to the upper floating platform which it is connected to. It is demonstrated that the suspended system's motion is described by the axial elongation of the suspension lines when positive tension is maintained in all suspension lines. An analytic solution for the equivalent stiffness of the suspension system is given. This suspension system stiffness introduces additional natural frequencies into the system, and the effects of these frequencies are demonstrated.

This novel concept requires a multibody modeling approach to perform a dynamic loads and response analysis, as the stiffness between the floating platform and the counter weight is provided by chains. Additional design criteria are required for the counter weight system dependent on a combination of chain capacity and maintaining positive tension in all of the suspension lines. To satisfy these design criteria a global hydrodynamic load and response analysis of the floating system is performed. In this concept, the counter weight depth contributes significantly to the dynamic properties of the system and therefore a parametric study is conducted. The global response parameters of the rigid-body motion, natural frequencies, nacelle accelerations, counter weight chain tensions, and maximum platform-pitch angles are compared. Following the parametric study, an ultimate limit state analysis is conducted on the original and alternative designs. Design recommendations are made for the counter weight depth and configuration of the suspension system layout.

This master thesis describes a method to determine the workability of an offshore heavy lift operation. By creating wave realisations based on and statistically equivalent to measured ocean weather data, a quick assessment of the risk of failure can be achieved.

DAMEN tugs can be found in nearly any port or terminal around the world. Operating in ports and terminals requires the tugs to be highly efficient in ship handling in order to quickly escort larger vessels. To predict the escort capabilities of a tug, DAMEN has developed the computer program DAMEN TUGSIM. Since the tool is becoming a decisive tool in the design process, DAMEN wants to strengthen their confidence in the simulation tool TUGSIM by gaining more understanding related to the thruster performance. The goal of this study is to quantify and increase understanding into the following regions: Thruster performance in oblique flow; hydrodynamic interaction effects encountered between thrusters; hydrodynamic interaction effects encountered between the thruster and hull. Recently performed model tests of the RSD (Reverse Stern Drive) tug provided the opportunity to gain insight into these topics and to derive prediction models. Mathematical models are developed and finally implemented in TUGSIM. Implementation of the new models in TUGSIM enabled to harvest new insight into escort capabilities of the RSD tug, especially into the braking capabilities.

The rudders of moored FPSO’s are fixed in the center to avoid unwanted rudder motions. This is often done by mechanical locking of the rudder machine. Due to waves and current, the loads on the rudder are higher than expected, causing failure of the locking system. An empirical study is executed to predict the combined wave and current loads on the rudder in moored conditions.

The new rapidly growing wind energy market has been moving to offshore waters the last few years. New techniques and growing experiences make it possible to move to challenging offshore domains and towards harsher conditions and deeper waters. From the oil & gas industry a lot of expertise is already available on support structures. The focus in this thesis is on the installation of a jacket type sub-structure for an offshore wind turbine. In more detail: the horizontal added mass for suction bucket jackets during installation was studied, from the moment the bucket touches the water till the buckets are fully submerged. This is a period during installation with a lot of uncertainties and unknowns, especially inside the buckets. A suction bucket jacket is identical to the commonly known jacket type support structure, however, at the bottom of each leg a suction anchor is attached. For a structure of about 60[m] in height and 1000[tonne], these anchors have a rough dimension of 8-9[m] in diameter and have similar heights. Note that the combined mass of the enclosed water inside the buckets can almost reach twice the weight of the dry structure. A benchmark suction bucket with dimensions 10[m] in diameter, 10[m] in height and a wall thickness of 10[cm] was used to design a scale model of 50[cm] diameter, 62.5[cm] in height and a wall thickness of 0.5[cm]. This corresponds to a Froude scaling factor of 1:20. The experiments were executed at the hydrolab at Boskalis, Papendrecht. A tank of 20x3.5x3[m] was available there to execute the experiments. The water-depth in the tank was 1.12[m]. During the experiments a vertical pipe segment was forced to oscillate at a known frequency. The pipe was attached to a guiding system, restraining all motions but the surge direction. The applied force by the actuator was measured by a load-cell attached at the point where the crankshaft was connected to the pipe. Simultaneously a LBT-sensor measured the position of the pipe versus time. The experiments were done for the following settings for draft and scale model wave period range, each experiment was executed three times to reduce the error: Periods: 2.46 2.24 2.01 1.79 1.57 1.34 1.12 0.89 seconds. Drafts: 0, D/4, D/2 3D/4 D. The data was filtered and analyzed with the use of the linear Least Squares Method (LSM). The raw data was fitted by adjusting the amplitude and phase of a sinusoidal fit signal. The amplitude and phase provide information on the relation between damping and added mass in the system. Finally the results added mass (and damping) were checked with the theoretical potential theory. While for all frequencies the added mass stayed more or less constant for each draft, during sloshing the added mass decreased. The damping was more or less constant for all drafts at low frequency, but at a wave period of 9[s] the damping start to increase for deeper drafts. Sloshing occurred at the shortest two periods. This had a significant impact on the damping and added mass terms. At sloshing the added mass decreased rapidly with 40%, while the damping increased up to 300%.

The main goal of this project is to determine the optimal location for an OTEC installation with a minimum lifespan of 30 years off the coast of Barranquilla and to make an anchor mooring design for the floater on which this installation is located. Bluerise has identified an area near the coast of Barranquilla for which OTEC can be applied. This area is situated within Colombia’s territorial waters (within 12 nautical miles, or 22.2 kilometres), where two locations have been identified by Bluerise: Location 1: 11.2028 latitude, -75.0003 longitude, Location 2: 11.2772 latitude, -74.9208 longitude.

Environmental conditions -
The daily wind direction is NE-ENE. There is no clear extreme wind direction. The daily waves have a dominant Northeast direction while the extreme waves have a dominant Northern direction. The extreme waves are generated far north of Barranquilla by very high wind speeds which explains the relatively high extreme significant wave heights in the area and the relatively low extreme wind speeds. The yearly average (nautical) surface current direction at the two possible floater locations is predominantly south or southeast. The top 20 strongest current speeds in the past few decades have come from the west or southwest however and therefore these are the normative current directions. The environmental conditions are equal for both possible floater locations. A temperature difference of 20_C is reached at warm water intake and cold
water intake depths of 30 and 763 meters, respectively. The depths at which a temperature
difference of 22_C is reached are 36 and 1023 meters (with temperatures of 27 and 5 degrees, respectively). The influence of the Magdalena river and upwelling is concluded to be negligible.

Marine traffic - The two locations with safety zones are located in a traffic-dense area. The area is getting more traffic intense in the upcoming years. However, it will not pose an immediate threat to the operation. As location 2 has slightly less traffic, it would be preferable from a safety point of view.

Seawater intake- and return pipes - Assuming a cold seawater intake temperature of 5C and a warm seawater intake temperature of 27C, the intake pipe lengths become 1023 and 36 meters, respectively. Based on the equation
of state, the mixed water return flow pipe length becomes 130 m. At this depth, the effects of a difference in density between the surrounding seawater and the mixed returned water are minimized. Also, the depth is outside of the euphotic zone which minimizes algae growth. If the intake water is higher than 27 degrees, the discharge temperature will have a higher temperature. Calculations with the Equation of State reveal that the warmer the discharge temperature,
the lower the density of the discharge water is. Whenever the discharge temperature is higher than the output temperatures, less depth is needed in order for the discharge water to be naturally buoyant. As the intake temperature fluctuates throughout the year, it is therefore advised to design the length of the discharge pipe at 120 meters.

Anchor mooring design - The proposed anchor mooring design consists of a spread-moored 4x3 taut mooring system. The lines are composed of three parts: a 50 meter chain connected to the ship, a 1290 meter fibre line part and another 150 meter chain at the end that is connected to the anchor. The floater is positioned in a 58,05 angle with respect to the north in a northeast direction. This ensures comfortable operation during daily conditions and will reduce fatigue build up. The hurricane conditions were found to be governing. The design complies with the basis of design stated in section 5.3 and with the DNV-OS-E301 code and the API Recommended Practice 2SK.

With the shift towards a more sustainable energy society, the increase in the electricity produced by renewable energy sources is steadily rising. However the cost of renewable energy sources still remains high compared to the traditional fossil fuel based energy sources. With the total worldwide energy demand also rising, combining renewable energy sources helps to reduce the cost through a shared infrastructure and increase in energy production. This thesis investigates the feasibility of a combination of floating offshore wind and marine current energy. As a basis the Hywind spar type floating offshore wind turbine is used. This 5 MW system is combined with a 1 MW marine current turbine. The characteristics of the current turbine will be examined with the program Aerodyn and the blades are designed with the program Harp_opt. As a cost reduction, the effect of scaling down the weight of the mooring system in combination with reversing the direction of the thrust of the current turbine is also investigated.

The program ANSYS AQWA is used to investigate the dynamic behavior of the
combined system. The thrust forces of the wind and current turbines are calculated via an external python server and added to the simulation in AQWA. The structure is modeled in a rigid body approximation, assuming no structural deformations. The behavior of the combined system is investigated in 3 operational and 1 survival load case. The operational load cases represent the environmental conditions of the cut-in, rated and cut-out wind speed of the wind turbine. In the fourth load case the system is subjected to survival conditions and the direction of the thrust of the current turbine is reversed. The environmental conditions are simulated with a steady wind velocity and the sea state is modeled using the JONSWAP wave spectrum. In all 4 load cases the system is subjected to a strong current.

By using a levelized cost of energy prediction model, a first estimation of the levelized cost of energy of the combined system is obtained. Adding a current turbine to the Hywind spar increases the cost of the initial investments and operational cost of the system, but also increases the total energy generation. Compared to the original Hywind spar, adding a current turbine to the system lowers the levelized cost of energy from 149.4 €/MWh to 142.3 €/MWh. Scaling down the weight of the mooring system lowers the levelized cost of energy to 141.9 €/MWh.

From the results of the simulations it is found that using the current turbine during survival conditions has a positive effect on the motions and maximum tension in the lines. It is concluded that by using the thrust of the turbine the weight of the mooring system could be scaled down, but the effect on the levelized cost of energy is minimal and doesn’t justify the increased risk of failure.

The Poineering Spirit is a heavy lift vessel that can lift offshore platforms in a single lift. Due to the waves, the vessel moves with respect to the platform. To make sure the vessel does not hit the platform, a motion compensation system is installed on the Pioneering Spirit. The maximum allowable vessel motions during
the operation are restricted by the capacity of the motion compensation system. Comparison of the predicted motions with measurements have shown good comparison for the deep water situation. It was found that prediction of the vessel motions in shallow water does not agree with the measuredmotions.
Therefore the prediction of the vessel motions in shallow water is investigated, to find out how do predicted vessel motions compare to measured motions. The goal is to quantify and reduce the uncertainty in vessel motion prediction in shallow water. First the calculation method of comparing the predictions to measurements was investigated and validated. The wave spectrum and as well as the Response Amplitude Operator (RAO) are available in 2D, The vessel response is available as a time series. To compare the predictions to measurements,
both prediction andmeasurement are translated to a 1D response. For the prediction, first the 2D response is calculated, which is then added over all wave directions to get the 1D response. The measured time series of the vessel motions are translated to a 1D frequency domain response using the Fast Fourier
Transform (FFT). The comparison of the 1D response spectra is done by comparing Significant Double Amplitude (SDA) and peak period Tp .
Comparison of the peak period has a relatively large error, with errors exceeding 0.5 s for most of the comparison for heave, roll and pitch. Looking at the SDA, the heave motions are underestimated for most of the time for low amplitudes. As the amplitudes increase, there is a spreading of the predicted motions above and below the measured values. Taking into account the motions with at least 0.4 m measured heave, the SDA is within 10 cm from the measured motions for 25% of the measurements. For the roll,the motions were underpredicted for larger motions, being at an incoming peak wave direction between than 220 and 260 degrees. The heave motions at the location of the topside lift system are dominated by the contribution of the pitch motions. The motions in shallow water are not accurately predicted in most cases, with a deviation from the heave at the sensor location by more than 10 cm. The response deviates above and below the measured motions. A possible explanation for the overestimation is the cushioning and sticking effect due to the presence of the seabed, this needs to be further investigated. The prediction of the peak period is limited by the precision of the buoy data. In order to do a good comparison for the peak period, the precision of the wave spectrum should be increased. This can be done by fitting the measured spectrum, or by using buoy data which has a smaller frequency step.

Dykstra Naval Architects are regularly designing large classic sailing yachts or motor-sailors, of which the draft is an important design restriction.The sailing performance is increased by adding lift-generating appendages,without increasing the draft. An example is a retractable centre board, havinga big influence on the sailing properties. Predicting the performance of the centre board contribution in a hull-keel-centre board configuration is the subject of this research. When predicting the performance of large sailing yachts, Dykstra wants to keep the ability to superpose an appendage to the data of a hull-keel configuration obtained from towing tank experiments or CFD simulations. This means that a method must be developed to estimate the contribution of the centre board, in terms of side force, resistance and centre of effort. Both towing tank experiments and CFD simulations are conducted for this research. The Maltese Falcon is used as the 'case ship'. A towing tank model of the Maltese Falcon was already made and tested at the TU delft in 2002. This model is again subjected to towing tank experiments, with a new keel and two new centre boards, resulting in 9 different hull-keel-centre board configurations. The main focus was on the towing tank experiments, executed in the Delft Hydromechanics Laboratory. CFD simulations were done to validate the results of the towing tank experiments and to gain visual insight in the flow around the vessel. The lift-carry-over on the keel and hull above the centre board can clearly be seen, as well as the influence of the centre board on the circulation in the flow around the underwater body of the yacht. After post-processing all experimental data, the results of the towing tank experiments are used to develop formulations to predict the performance contribution of the centre board. The measured lift of the centre board contribution was roughly a factor 2 higher than the centre would generate according to Wicker & Fehlner theory. Additionally, it was found that the lift-carry-over does not only have a positive effect on the generated side force, but also on the resistance. Furthermore, it was found that heeling the Maltese Falcon model by 15 degrees, yields the same magnitude oflift-carry-over as for the upright conditions. This resulted in the conclusion that heeling the yacht has no influence on the lift-carry-over from centre board to keel-hull. The new prediction methods, derived from the towing tank experiment data, are validated on YACHT1 and Adela. These are existing yachts with hull-keel-centre board configurations, but both very different. This enabled an interesting examination on the influence of certain aspects of the configuration on the performance of the centre board contribution. All in all, it was found that the predicted centre board contribution corresponded really well to the measured data of YACHT1 and Adela. This provides enough trust to implement the new centre board performance prediction methods in the Dykstra performance prediction tool. Every new design cycle of a yacht with hull-keel-centre board configuration will serve as a validation of the derived performance prediction methods.

Large water motion inside the moonpool of vessels operating in waves can be excited by pressure fluctuations produced by external waves and vessel motion. Extreme consequences of this effect may include injuries for crew members, and damages to deck equipment resulting in downtime for the vessel. The accepted method to predict this non-linear phenomenon is a combination of model tests and potential solver. Nevertheless, model tests are generally conducted at the end of the design phase leading to serious problems if the moonpool performance is not sufficient. CFD solvers proved their capability of modelling complex flow phenomena and their use as a design tool for the moonpool is growing. However, a complete verification & validation is still missing. In the present work the water motion inside a moonpool and the forces on the hull, for a vessel in head waves without forward speed, are estimated using the MARIN software ReFRESCO. In doing so, the goal is to define the accuracy of the code for a rectangular moonpool with sharp edges without additional damping devices. For a deeper comprehension of the physics involved, a stepwise approach was followed. The work starts with an empty domain in which only regular waves were generated to assess the propagation and absorption of waves in ReFRESCO. Secondly, fixed vessel simulations were performed to study the influence of grid dimension, mesh refinement and boundary conditions. Then forced heave oscillations were simulated to estimate the damping and added mass. Verification studies were carried out for all the presented to this point. Finally, results from free-floating simulations were validated against experimental results.

When working offshore on a floating vessel, the vessel will be subjected to wave induced motions and with a moving crane tip, a suspended load can start to swing. When the motions of the load become too large, the operation is interrupted. Alternatives such as jack-ups, function as a fixed platform to which the crane is attached, therefore eliminating the effect of waves on the workability of the vessel. Within the offshore wind industry, jack-ups are used for installation and maintenance of wind turbines. However, due to their slow transit speed and time-consuming jacking process, an alternative is suggested with which wind turbine maintenance can be performed. In this thesis study, the mechanical feasibility of a motion compensated crane for wind turbine maintenance is assessed by comparing three different crane concepts.

Airborne Wind Energy (AWE) is a field of engineering that utilizes tethered aircraft for the generation of electrical power. The potential for the application of AWE in deep-water offshore environments on top of floating foundations is enormous. Where conventional wind turbines would require a very stable platform to reduce motions at the nacelle, AWE requires just enough stability to survive extreme conditions, take-off and land horizontally, and not negatively affect cross-wind performance. The requirements scale well with increasing capacity of AWE systems, which mostly influences the mooring configuration instead of the steel structure. That is why Ampyx Power started an investigative study into the floating offshore application of AWE in collaboration with Mocean Offshore, MARIN and ECN.
A driving factor in the design of the floating foundations is the maximum allowed motions in different sea states. The objective of this research is to determine the relative magnitude of the effect of platform motions on the landing performance. This will result in more clearly defined design requirements for both the floating platform and the aircraft. The method used in this research can be extended to more advanced numerical models at a later stage of the design to obtain quantified motion constraints or operational limits.
It is assumed that standard deviations of several parameters at the end of the landing approach serve as good indicators of successful landings. A numerical model of a tethered aircraft (RPA) making a horizontal landing in time domain is developed to determine these parameters in a multitude of wind conditions. By performing a Monte-Carlo analysis, the standard deviations of these parameters can be acquired. Especially symmetric motions (X, Z and RY) are expected to affect landing performance, which is why a 3DOF model is used. Then harmonic platform motions are included in the model in order to investigate what type of platform motions are most critical. Finally, the platform designed by Mocean Offshore is examined. By combining the motion response of this platform with metocean data at a reference location, the standard deviation of critical parameters is obtained in comparison to an onshore application. The motion response of the platform is determined using a numerical model that combines potential theory with semi-empirical drag formulations. This model is validated with basin tests at MARIN.
Simulations with harmonic platform motions indicate that both frequency and amplitude of platform motions are critical for the landing performance. The landing performance appear to be mainly related to the platform motion velocities. Therefore, increasing damping and added mass of the platform will both have a positive effect on the landing of the RPA.
When looking further at the results of the simulations with platform motions based on metocean data and the hydrodynamic, numerical model, it was found that the current design of the floating platform by Mocean Offshore leads to an expected decrease in landing performance compared to the onshore application. The performance decrease is not insurmountable, and multiple methods of reducing the negative effects on landing performance are presented.

Jumbo Maritime is a heavy lift shipping and offshore transportation & installation contractor. The Fairplayer is one of the J-class vessels that is capable of performing offshore installation work. The two 900 ton Huisman cranes can lift up to 1800 ton combined, but the insufficient static stability of the Fairplayer results in a maximum lifting capacity of 1000 ton in offshore conditions. This limited lifting capacity in offshore conditions is a missed opportunity to make use of the Fairplayer in a wider segment of the offshore installation market. In this research, the increase of static stability is obtained by the use of a sponson. A sponson is an extension of the hull, which can be seen as a local widening on the side of the Fairplayer. This sponson is expected to result in an increase of the total resistance. The goal of this thesis is to investigate the influence of the position and shape of a sponson on the Fairplayer with respect to the resistance. The influence of the position and shape of a sponson is analysed by the variation of the longitudinal position, the vertical position and the length over width ratio of the sponson. A combination of the Holtrop-Mennen method and the potential flow program RAPID is used to give an estimation of the increase in resistance. RAPID is used to calculate the influence of the wave-making resistance of the Fairplayer, whereas the frictional resistance is calculated according to the ITTC-57 flat plate friction formula and a form factor. It can be concluded that the position of the sponson turned out to have a significant influence on the wave pattern and therefore on the wave-making resistance of the vessel. The sponson can be positioned in a way that the wave system generated by the sponson interferes with the wave systems generated by the vessel. With this combination of the Holtrop-Mennen method and RAPID, a position of the sponson is found where the increase of the total resistance is minimized to 7%.

Floating offshore wind energy is being widely implemented in deep-water sites thanks to its numerous advantages, which among others include the access to stronger and undisturbed wind resources. In addition, considering the fast-paced growth in size and power generating capacity of offshore wind turbines, the designs of floating foundations need to be continuously improved. Therefore, proper testing (at model-scale) is necessary.

To achieve this, several factors need to be taken into account. For instance, down-scaling for testing of floating structures brings challenges due to the so-called Reynolds effects, which degrade the aerodynamic response of the mounted turbine. Likewise, the rotation of the blades and the motions of the platform as a result of its interaction with waves, have an impact on the wind inflow acting upon the rotor. Thereby, modifying its instantaneous performance.

This Master thesis, carried out in cooperation with MARIN (Maritime Research Institute Netherlands), focuses on developing a reliable methodology that renders in the design of a scaled-down thrust-matched 10MW wind turbine rotor blade, for its further implementation in the testing of a floating offshore support structure.

For this purpose, the aforementioned effects are investigated, and a suitable set of design tools is selected and coupled, in order to realise an optimised blade geometry. For predicting the wind turbine behaviour, this implementation relies on the Blade Element Momentum Theory. Furthermore, the resulting blade's aerodynamic performance is validated using ReFRESCO (MARIN’s in-house CFD code), against the non-dimensional parameters of the DTU 10MW reference wind turbine.

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.