The offshore wind sector is a fast-developing sector, with turbine sizes increasing year after year.
This thesis investigates the evolution of the foundation installation sector, highlighting technological advancements, scaling challenges, and future opportunities. The installation of foundations has become increasingly complex, due to the increasing turbine sizes, deeper water projects, and stricter environmental regulations. The research identifies scaling challenges such as handling larger foundations, adapting vessels, and lowering environmental impacts like noise pollution. Furthermore, the study looks into how the future of the foundation installation sector will develop, and what will influence the future growth of the sector.

This research combines past developments with future trends to provide valuable insights into how the offshore wind industry can continue to grow sustainably. The findings highlight the importance of innovation, collaboration, and adaptability in meeting the ambitious renewable energy targets.

Offshore wind energy has become a important contributor to global renewable energy efforts, particularly as the industry seeks to expand into deeper waters where traditional fixed-bottom turbines are no longer feasible. In these deeper waters, floating offshore wind turbines (FOWTs) offer a promising solution, allowing for the generation of renewable energy in locations with stronger, more consistent winds. However, with the increasing use of FOWTs comes a set of logistical challenges that need to be addressed to ensure their commercial viability and large-scale deployment. One of these challenges is the large-scale production of floating foundations. One significant challenge to the commercial success of FOWTs is the slow fabrication rate of semi-submersible floaters, which require extensive welding and assembly. In contrast to faster monopile fabrication, these floaters are more complex and take longer to produce. Since installation campaigns are typically limited to favorable weather periods, especially in the summer months, many floaters need to be ready in advance, placing strain on fabrication yards and causing space constraints. Wet storage provides a viable solution by allowing temporary storage of floaters in coastal areas, freeing up space in fabrication yards for continuous production. This research explores the existing literature
on wet storage mooring systems and identifies key design criteria, environmental considerations, and components such as mooring lines, anchors, and auxiliary equipment.
To evaluate mooring system designs, a Multi-Criteria Decision Analysis (MCDA) framework was developed, facilitating structured comparisons and trade-offs between various design objectives. Although the MCDA enables informed decision making, dynamic analysis is essential to obtain deeper insights into system performance. In this study, frequency domain (FD) analysis was employed for rapid evaluations of the behavior of the mooring system. FD analysis proved sufficient for preliminary studies and is an ideal tool for exploring design variations. It efficiently captures first-order loading effects, which are typically dominant in expected wet storage conditions. However, for detailed design stages, to account for nonlinear behaviors such as slow drift and mooring line stiffness, time domain (TD) analysis are recommended to validate final configurations and ensure compliance with design codes.
Dynamic analysis of the mooring systems compared catenary and taut configurations under various environmental conditions. Concept-specific constraints such as maximum fairlead tension, uplift allowance, mooring line angles, and minimum anchor distances were incorporated into each mooring concept. Furthermore, diffraction analyzes were conducted with varying water depths and floater drafts to accurately define floater behavior under different conditions, and a mesh validation was performed to ensure that the mesh was fine enough for this study. Further validation of the full model was done by comparing the calculated Load Response Amplitude Operators (RAOs) and natural frequencies with
the reference turbine to ensure model accuracy. Tidal ranges and line diameters significantly influenced mooring performance, impacting tensions loads, and floater displacements. The results indicated that the catenary system consistently met these constraints and demonstrated resilience across the full tidal range, where a clear trade-off between tensions and displacements can be observed. However, the taut system experienced tension overloads, particularly at high tide, where it often exceeded line breaking strength, with only a single taut configuration yielding valid results. Despite being more spatially efficient, the taut system’s reliability was compromised compared to the catenary system. Several recommendations for future research are identified to further the understanding of mooring systems in wet storage applications. These include conducting TD analyzes to capture non-linear behaviors, exploring alternative mooring configurations such as Honeymooring or pile fields, refining design standards, and evaluating the economic and logistical feasibility of wet storage solutions. Additionally, investigating different storage locations is essential, as this study focused on a single location, and variations in environmental conditions could significantly influence mooring performance.

In the last decades, the urgency for sustainability has dawned on humanity. The increasing pressure for more renewable energy sources is accompanied by the success of the offshore wind turbine. As a result, the installation of offshore wind farms has become a major business. The challenges posed during installation become more complicated with larger turbines. Forces exerted on taller and softer support structures and longer blades limit the installation options of the wind turbine components even more.
Nevertheless, the dimensions of wind turbines have grown explosively over the years and this growth is foreseen to continue.
To overcome the growing challenges of blade installation on offshore wind
turbines, it is crucial to better understand the forces and the induced motions. Insufficient understanding of the behaviour of the support structure and blade during installation of the latter could lead to over-conservatism of an already vastly time-constrained process, resulting in loss of workable weather and unnecessary costs.
The objective of the research conducted in this thesis is to develop a dynamic model of a 20 MW offshore wind turbine to quantify motions at the blade-hub interface during blade installation and examine potential mitigations. When the objective is reached, a good comprehension of the blade behaviour is achieved, allowing for exploration of solutions to reduce the observed motions and increase workability.
A 20 MW wind turbine does not exist as of writing, but with a scaling assessment a configuration was composed. The future wind turbine is estimated to have a hub height of 154.7 m and a blade length of 131.5 m with an estimated weight of slightly less than 90 tonnes. Due to offshore placement of the wind turbine, the length of the support structure is estimated to be extended with a water depth of 35 m. The problem has been further delineated by assuming the weather conditions of a typical North Sea offshore site at the boundary of what is currently possible for blade installation. Installation is assumed to be conducted with a floating vessel, posing even more challenges.
Modelling the installation of a blade is subdivided into examining the behaviour of a wind turbine support structure and a blade suspended from a crane separately. The performed simulations are conducted in 3D, with the support structure and blade being multi-body systems excited by unidirectional
waves, wind and current. Calm, normal, and rough weather conditions are assumed as input conditions to examine the environmental impact. A combination of the results of the models simulating the multibody systems provide the relative motions between the support structure and the blade, resulting in potential impact velocities in the horizontal plane. The model is solved in the time domain, because it allows for a better understanding of the input and output variables...

As the world economy and population grow, energy consumption grows too at a never before seen pace. Reducing costs and increased environmental awareness resulted in renewable energy sources being the fastest-growing sources in the last decade. Due to its high potential, many offshore wind turbines will be installed in the coming years. These turbines will be installed in deeper waters, usingmainly monopiles as support structures.

In the variety of monopile (MP) installation methods, a distinction exists between installation over the side of a vessel and a novel method where the procedure is repositioned to the vessel’s stern. Experts in the field were convinced that stern installation would be necessary for growing MPs and extended installation timeslots. This thesis aims to create an objective distinction between the installation directions by looking at the following two installation steps.
First, the storage of MPs on the deck of an installation vessel is investigated. For side installation, the MPs are positioned transversely on the deck. This method uses little deck space per MP but includes an overhang which might badly influence the vessel’s behaviour. The latter has been investigated
using the Moment of Inertia (MoI) of the vessel as an indicator of this behaviour. It has been found that transverse storage affects the MoI significantly more than longitudinal storage. However, this longitudinal storage is limited to 4 MPs per transit due to stability, whereas the transverse method can take 6 MPs. The stresses in the MP itself have also been evaluated for these storage methods, as the support locations were different. It has been concluded that there is indeed a difference, but the stress level has been found not governing for this choice.

Second, the upending procedure is investigated, as this is a step in the procedure which is highly influenced by motions and external wave impact. A model is developed that uses tugger line connections from the vessel to the MP to define forces in equipment objectively. It has been found that loads in the tugger lines were significantly lower for stern installation compared to side installation, which leads to a workability comparison. This comparison is based on a specific tugger cable, limited to a 300𝑚𝑡 tugger load. A range of sea states has been analysed and checked on this maximal tugger load. The workability difference for full-year performance is found to go from 64% for side installation to 96% for stern installation. It is realised that these numbers are high compared to the actual installation, but as the assumptions made for this model are equal for side and stern, these percentages are a good comparison between the two methods. The assumptions on which this model is based are checked on
sensitivity, which results in reasonable trend lines and an interesting prospect into the future.

The model presented in this thesis could pose as a hypothetical concept for future installation, and therefore a determination of the natural frequency is added in this thesis. With this natural frequency, the feasibility of a concept can be quickly assessed even though no time-domain simulations have been
executed. The model stays clear from natural periods of the control system and periods of the waves for a large range of upending angles. However, in a nearly vertical position, the control frequency is crossed and later, the regime of wave frequencies is encountered. Adjusting the model slightly in terms of geometry shows that these issues can be solved. However, future research is highly recommended into a time simulation of the model.

Finally, some practical applications of the installation over the side and stern are discussed. Concluding this thesis, the main research question can be answered positively by stating that stern installation can be used to improve the all-year MP installation performance of a floating installation vessel.

With an increasing shift to renewable energies, solutions are required to overcome that variability and unpredictability of power production that comes with it. Hydrogen is one solution that can overcome this issue since it can be produced using renewable energy through electrolysis, it can be transported to shore efficiently by pipelines and it can be stored, like natural gas. Not only can hydrogen be used as a way to store energy, but it can also be used directly as a basis for steel production and for long-distance transport. Using wind energy, specifically offshore wind farms, as the source for hydrogen is an idea that is gaining attention. Currently, wind turbines are electrically connected, bringing their electricity to shore by high-voltage cables, allowing hydrogen to be produced onshore. Hydrogen could however also be produced at a central location in the offshore wind farm or at each individual offshore wind turbine, removing the need for high-voltage cables. The purpose of this research is to explore different methods of hydrogen production and validate a model that can simulate each method. The goal is to be able to compare the different methods and quantify the losses of producing hydrogen offshore as opposed to onshore. A time-based simulation model has been developed to represent an offshore wind farm, which would either produce electricity or hydrogen, which eventually arrives onshore. High-resolution wind data are used to correctly include short-term fluctuations in wind output. The N.O. Jensen wake model is implemented to capture the wake effects. Since wake is typically modelled steady-state, specific attention has been given to include the moving of the wake through the wind park. The power outputs for each turbine in the model could be accurately determined based on the incoming wind data. It is found that the spatial effect reduces wind power variations at the wind farm level to about 22\% of first turbine in the sting, as expected. The output of the simulation model compares the power losses of producing hydrogen through four scenarios. This model uses a total of eleven wind turbine strings of seven 10 MW wind turbines each. The power output calculated would then be used to determine the amount of hydrogen produced. By applying electrical power loss equations and calculating the pressure drops for hydrogen traveling in a pipeline by assuming steady-state and isothermal, the losses are calculated for each scenario. A sensitivity study is performed to see the effects of changing model parameters on each of the different scenarios. The model developed in this thesis allows for comparison of electricity production and hydrogen production by offshore wind turbines. It is found that producing hydrogen at the wind farm level and then transporting hydrogen to the shore (Scenario 2) has lower overall energy losses (kg of hydrogen available on shore) than using electrical cables. The same goes for individual offshore hydrogen production (Scenario 3). A high-level exploration of the economics indicates that both scenarios 2 and 3 are more economically feasible when only looking at transportation costs. It is recommended that further research is done to be able to determine which method of hydrogen production would be the most effective by taking the transportation losses and economics into account.

This research explores the development of an accurate yet fast methodology to use measured vessel motions for a fatigue damage calculation in the cranes during suspended transport. First, the kinematics, definitions and particulars of the system of interest – the vessel including crane and suspended jacket - are provided. Then, literature research is done on the main two problems with any transport at sea: the inconvenient draft problem, and the forward speed problem. To remove the inaccuracies introduced by both problems, the novel TF A2B Method is introduced. The method can be used to find the required force transmissibility functions at location of the cranes that are most prone to fatigue: the welds at the crane boom pivots. It is mathematically proven that the TF A2B Method can be used and with validation tests set up for unrestrained suspended transport it is shown that the required RAO’s can be obtained from in-house modeling software Liftdyn. Overall, its concluded that the TF A2B Method works in principle, removing the need to consider inconvenient draft and forward speed.

The hypotheses proposed in this research are further validated by the proposed validation tests in combination with a synthetic data model created in software tool Liftdyn. The Synthetic Data Model (SDM) uses a Jonswap Spectrum to obtain the motions at the Motion Reference Unit (MRU, ‘A’) and the Control Point (‘B’) at the modelled SSCV Sleipnir, which is assumed as a rigid body. After successful validation, the SDM model is then used to calculate the motions at the Jacket Sensor (‘B’). Further validation of the found responses is done and it is confirmed that the location ‘B’ can in fact be located on another rigid body as the MRU, which in this research was the location of the jacket sensor. It is also shown
that the transmissibility functions (TFs) between A and B are almost equal for different draft, resulting in that the TFs between A and B are not significantly dependent on the hydrodynamic properties of the modelled system. Therefore, it is concluded that the TF A2B Method can correctly find motions at location B by using the motions of location A in combination with the corresponding TFs between A and B.

The TF A2B Method is then applied to calculate the jacket motions using measured vessel motions. Data obtained from the X suspended transport were processed and applied using the Measured Data Model. The calculated jacket motions are compared to the measured jacket motions during the X suspended transport to the accuracy of the TF A2B Method with real data. An approximate 70% accuracy match with the measured suspended jacket motions, Roll and Pitch during the X Suspended Jacket transport was found. It is noted that not all data was found to be suitable for use. Suggestions for improving this have been made and are expected to further improve accuracy of the match. The validated Liftdyn model of the X transport is then used to model the suspended transport of X. From the Liftdyn model Force RAO’s can be obtained at the selected fatigue location of the cranes. A Fatigue Data Model using the TF A2B Method is proposed to find the stress cycles and thereby the fatigue damage during suspended transport.

Concluding, the TF A2B Method developed in this research shows positive results overall. The method can in principle be used to translate vessel measurements during suspended transport into fatigue life consumption of the crane. Further research is needed to improve the Measured Data Model, for which the use of a Surge and Sway motion sensor at the MRU is recommended. Furthermore, smaller vessel motions and more data samples should be used to further validate the accuracy of the method which is required to validate the Liftdyn model of the transport. Finally, to verify the results of the Fatigue Data Model, it is suggested to install strain gauges at the welds of the crane boom pivots for validation.

The offshore wind energy industry has been developing rapidly due to the increasing demand for renewable energy. As a result, offshore wind turbines are increasing in mass and height and are installed at larger water depths and further away from shore. A floating vessel is not limited by water depth and soil conditions, but is sensitive to wave-induced motions. Heerema Marine Contractors developed a new installation method using a floating vessel, where the rotor nacelle assembly (RNA) of a wind turbine is assembled on an assembly tower on deck and is installed in one lift. The research objective is to gain a better understanding of the dynamic behaviour of a rotor nacelle assembly, particularly due to the wind, focusing on the horizontal motions of the RNA, when it is hanging in the crane above the tower. To examine the dynamic behaviour of the RNA, separate models are made to assess the effect of the wind and waves individually in OrcaFlex and Liftdyn. This is done to identify which motions are due to the wind, and which motions are due to the waves. Finally, the wind and waves are coupled to gain insight in the coupled response. Furthermore, a case study is performed to prove its applicability for implementing and assessing the effect of using tugger lines on mitigating horizontal motions. In the models the blade pitch angle, crane position and responses for different wind and wave conditions are examined. From the different models is observed that the response due to wind cannot be neglected. Wave-induced motions are governing, due to large crane tip motions. The governing motion is a pendulum motion of the RNA, which is larger for longer wave peak periods. For both short and long wave peak periods, the horizontal motions have to be mitigated. In the case study, tugger lines are implemented to examine the effect on the RNA motions and to assess if the model can be used for developing concepts to reduce the motions. It is shown that providing stiffness in the horizontal plane and in roll help to reduce the sideward pendulum. For long peak periods, the RNA motion has to follow the opposing motion of the crane tip. More research is required to develop a concept that can follow the crane tip for short peak periods and oppose the motion of the crane tip for long wave peak periods.

During the past decade, the offshore wind energy industry evolved to bigger turbines, going into deeper waters and farther offshore. As bottom-fixed wind turbines are limited to shallow water depths, floating wind structures are the next frontier to unlock the vast potential of wind energy. Despite many techno-economic challenges, several full-scale floating wind structures have been successfully deployed and have shown the potential for floating offshore wind. One project near completion is the 3.6 MW TetraSpar demonstrator developed by Stiesdal Offshore Technologies, Shell and Innogy. With its tetrahedral shaped base and suspended counterweight keel, developed with the focus on ease of fabrication and installation, this spar concept is expected to offer a competitive package for floating wind using future, larger 10 MW+ wind turbines. The goal of this research is to investigate the capability of the TetraSpar platform to accommodate significantly larger wind turbines and to identify challenges in an early stage of development. Since technology upscaling of floating wind substructures has not been done before, this thesis first develops a novel design methodology for upscaling and then is applies it to the TetraSpar as case study. This work builds on academic efforts thus far but focusses on the key design drivers in for upscaling of floating wind, namely the fundamental equilibria in vertical and rotational direction: the structure’s weight is equal to its buoyancy, and the restoring moment equals the maximum overturning moment by wind. Specific emphasis is put on correctly capturing these equilibria, as they generally apply for floating wind substructure technologies, including the TetraSpar. First a design basis is created with functional requirements and design criteria for floating wind structures in general, and specifics to the TetraSpar. Also, key specifications of future 10 MW, 15 MW and 20 MW wind turbine types are explored. Secondly, a model is developed for upscaling based on physical modelling of hydrodynamic stability (water and waves) and aerodynamic thrust (wind). Based on these inputs, the substructure is upscaled using the future turbine type wind thrusts. The model employs an algorithm to find a new equilibrium design point and computes key properties for upscaled substructures. The resulting design concepts are then evaluated for first order wave-structure interactions using a diffraction/radiation solver (WAMIT). Key evaluation aspects are free-floating hydrodynamics, including hydrodynamic coefficients, wave forces and response amplitude operators. Fourth, selected structural elements of the upscaled design concepts are evaluated for structural strength. The fifth and final step assesses the extent to which the now evaluated upscaled design concepts still meet on the functional requirements and design criteria. The thesis concludes that the developed, first-order design methodology is suitable to explore upscaled design concepts of floating offshore wind turbines. By computing an estimation of the physical dimensions and behaviour of the substructure, this allows for the evaluation of the technical and economic feasibility. Key findings of the physical modelling are the linear trends for structure mass over power rating of the wind turbine, sensitivities in design choices for maximum allowable heel angle due to wind, and keel draught for the TetraSpar specifically. Compared to other technologies, it is found that found that the TetraSpar concept offers a relatively lightweight platform for future wind turbines up to 15 – 20 MW. No fundamental technical showstoppers are identified for upscaling, but it is found that as the structure progresses to larger wind turbines, aspects like in-port water depth, physical dimensions of structural elements, and installability of the TetraSpar at sea will become more challenging. It is expected that at some stage in the development towards large-scale floating wind structures, trade-offs will have to be made to arrive at an improved design. For this, the methodology developed for this thesis can be applied, for example by exploring a lighter, wider TetraSpar design with more slender structural elements. Furthermore, it is recommended to further investigate the mooring design, fabrication capacity and deployment procedures of larger floating wind substructures in general, and upscaled TetraSpar designs in particular.

In the design of offshore wind turbine generator (WTG) support structures, a large number of environmental parameters are used. The most important ones include the wind climate (wind speed and wind direction probability distributions), the wave climate (wave height and wave direction as well as peak frequencies of the waves, and water levels) and the soil conditions. These data in combination with the operational data of the wind turbine, such as the rotor speeds, pitch angle and yaw angle are used in dynamic simulations to determine the loads on the structure. Combining all these data correctly ensures that the support structure design, which is subject to large dynamic loads, is fitting for each specific location of the WTG. In particular, the environmental conditions should not coincide too much/often with the support structure natural frequencies, as that may result in resonance, thereby increasing fatigue life consumption. The dynamic behavior of these offshore support structures is of eminent importance. During the operation of WTGs, the actual dynamical properties of the WTG can be compared to the design. There are several reasons behind the goal of this comparison, for example verifying if the loading assumptions in the design were correct, assessing whether the life time can be extended or even whether the structure can be optimized (e.g. better foundations). Typically, this is done by comparing acceleration measurements of the WTG during idling (e.g. non-operational) conditions and applying Operational Modal Analysis algorithms. Given the high availability of modern wind turbines (e.g. >95% of time in operation) such measurements cannot be done as often as desired for this purpose. Therefore, the question arises to what extent the dynamical properties of WTGs can be estimated using measurement data obtained during operational (operational) conditions. This research explores the applicability of OMA algorithms in estimating the dynamical properties: the natural frequencies, the mode shapes and modal damping for operational conditions of offshore wind turbines on monopile foundations, using the Luchterduinen offshore wind park as a case study. The OMA technique explored in this thesis is Eigensystem Realization Algorithm. Test cases were used to confirm the performance of ERA for the estimation of the dynamic parameters. Stability diagrams were used to identify poles for stable modes (frequencies) in the frequency spectrum of data samples and to estimate a correct size of the Hankel matrices. It is concluded that this preprocessing and pre-analysis of the results is important to confirm the performance of ERA to correctly identify stable modes of support structures of operational offshore WTGs.Overall, it is concluded that ERA can yield useful results in estimating the natural frequencies for both ON and OFF, provided that an automated analysis is combined with a visual analysis. Even then, the accuracy and the consistency of the identified frequencies is moderate. ERA does not perform well for estimating the mode shapes, yielding inaccurate and inconsistent results. Based on the results of this work, ERA is found not to be capable of estimating modal damping ratios. The consistency for the mode shapes is not in all cases good and further study is recommended for both the mode shapes and the modal damping ratio. Another recommendation is to further study the size of Hankel matrices for this application. Furthermore, it is advised to also investigate the use of more advanced Operational Modal Analysis algorithms. The results of this study may be used to explore differences between wind turbines with and without scour protection and also to compare identified dynamic parameters to values used in the design.

Wind farms are increasing in size to keep up with the increased demand for renewable energy. Larger wind farms, leads to more complex wind farm design problems for a designer. This study investigates the wind farm design process and compares computed and manual design approaches in order to find the best solution to the wind farm layout optimization problem.

In this study, the design process of a wind farm is described in detail based on the
experiences of two designers in order to get a clear view on the current state of wind farm designing. Different experiments were performed to compare a manual and a computed design approach for an offshore wind farm. It turned out that the computed designs led to a 1 % increase in energy capture compared to the manual designs. Further research is required to conclude that computed design approaches always lead to higher energy yields, however, it was found likely that the computed approach is the best method to solve the wind farm layout optimization problem. The main problem with the current available optimization software is that it cannot deal with all constraints. Therefore, optimizing a
wind farm design still requires some manual changes to fulfill all requirements for the project.

In current offshore wind turbine (WTG) tower installations, bolted flange connections are common. These connections are however reaching their limit due to the maximized size of the bolts. Also, bolted connections require the motions between the tower and foundation to be limited during installation, suggesting their workability of installation is low. The Double Slip Joint is a promising and innovative connection between a WTG tower and the support structure, which may remove or reduce these limitations. This research explores the motion and collision limits for WTG tower installation on a monopile (MP) foundation and focuses on the lowering and mating using two types guiding structures, or catchers: the vertical asymmetric catcher and the conical catcher. A first exploration of installation workability is provided as well. A model is developed that simulates the lowering and catcher mating of a WTG tower with a MP. This model includes physical phenomena that affect the motion and collision behavior of the WTG tower. Specific attention is paid to collisions between the catcher and the MP. With the use of finite element analysis, a stiffening non-linearity is observed in the lumped contact element to describe collisions. It is found to be caused by the local deformation of the mating elements. Furthermore, the simulation model calculates 3 degree of freedom in-plane motions numerically of the WTG tower in the time domain using Euler integration. Besides the aforementioned stiffening non-linearity in collisions, other important model features are a time and spatially variable wind load, aerodynamic damping, harmonic horizontal and vertical crane tip motions, crane operator induced crane tip motions and lifting line stiffness and damping characteristics. The model simulates the WTG tower lowering and catcher mating and to determine the installation limits, installation requirements have been defined, aimed at preventing critical events. To be specific, installation requirements aim to prevent slack wires, axial impact, and plastic deformation of the catcher due to contact with the MP. It is also required that the side-lead angle (i.e. the lifting line angle with respect to the vertical) remains below a maximum allowable value. Model simulations are performed for both jack-up and floating installation vessel crane tip excitation characteristics. This research indicates that in both cases, the conical catcher yields higher allowable wind velocities than the vertical asymmetric catcher during installation. This is supported by the findings that the conical catcher has higher allowable contact forces, requires less or no crane operator action during catcher mating and the side-lead angle varies less than with the vertical asymmetric catcher. Another important observation is that the installation limits are often reached through installation requirements related to the motions and collisions of the mating elements. This study shows that applying linear damping to the horizontal WTG tower bottom motions, achievable by (active) tugger winches, the allowable mean wind velocity in installation is increased and this research suggests that the workability of installation increases consequently. The focus in this study is on motion and collision limits in installation as well as on installation requirements. It is recommended for future research to focus on workability and to analyze the entire system consisting of vessel, load, and foundation. As such, wind and waves are considered separately as a source of excitation and vessel-load interaction is incorporated. For 3D analyses, it is recommended to study the control of out-of-plane WTG tower bottom motions and potential inclined collision responses between the catcher and foundation.