To decrease Europe’s harmful emissions, the European Union aims to substantially increase its offshore wind energy capacity. To further develop offshore wind energy, investment in ever-larger construction vessels is necessary. Designing these vessels is difficult however, as this market is characterised by a large but seemingly unpredictable growth of market demand, turbine size and distance from shore. Currently no way of dealing with such market uncertainty within the ship design process was found to exist. This research aims to develop a method that is able to deal with market uncertainty in early ship design by increasing knowledge when design freedom is still high. The method uses uncertainty modelling prior to the requirement definition stage by performing global market research, and during the concept design stage by iteratively co-evolving the vessel design and business case in parallel. The method consists of three parts; simulating an expected market from data, modelling multiple vessel designs, and an uncertainty model that evaluates the performance of the vessels in the market. The case study into offshore wind foundation installation vessels showed that the method can provide valuable insight in the effect of ship design parameters like main dimensions, crane size and ship speed on the performance in an uncertain market. These results were used to create an initial design that is expected to perform well in the uncertain market. The developed method thus provides a way to deal with market uncertainty in the early ship design process.

The offshore wind energy sector is rapidly growing with an increase in the capacity of offshore wind turbines, resulting in increasing dimensions of offshore wind turbines and their foundations. Additionally, there is a tendency to locate offshore wind farms more offshore because of more consistent wind speeds and more space. Sites with a water depth less than 70 metres are suitable for fixed-bottom foundations. A commonly applied fixed-bottom foundation is the monopile due their simplicity, ease of installation, and relatively low costs. Over the past years, the diameter of the monopile increased from an average of 5 metres tot 10-12 metres. These ever-growing monopiles need to be installed from floating vessels, such as heavy lift crane vessels, which are not dependent on water depth, instead of jack-up vessels. During installation, heavy lift crane vessels form a multi-body system with the crane and monopile and pile gripper ring, inducing coupled dynamic behaviour, resulting in resonance behaviour. Currently, monopiles are installed at the side of a heavy lift crane vessel. However, a new technology is in development to install monopiles in a recess at the stern of the vessel. The upending and lowering of stage of monopile installation are considered as critical events and it is obligatory to assess the operational limits of these stages during the planning phase. The purpose of this thesis is to compare side and stern installation of 2XL monopiles from a heavy lift crane vessel during the upending and lowering phase in terms of operational limits. Therefore, a case study is performed, using Hornsea Offshore Wind Farm on the North Sea as a reference project. Time-domain simulations are conducted in OrcaFlex for various significant wave heights and spectral peak periods for both side and stern installation. The operability of the mission equipment is assessed, resulting in a comparison for side and stern installation. It is found that during upending stage, stern installation provides a larger operability window compared to side installation. During the lowering stage, side and stern installation have a comparable operability window. In conclusion, stern installation shows promising results to further develop this installation method.

The offshore wind market is growing rapidly, and new offshore wind projects are being launched more than ever. To keep up with demand, parts for these wind turbines are being produced all over the world. To get all the parts needed to their destination on time, they must be transported on heavy transport vessels (HTVs). Today, business cases focused on maximizing profits dictate the design of these vessels. Despite the upcoming energy transition, the environmental impact of these vessels is usually neglected. Therefore, there is a need for a method to evaluate the economic and environmental performance of HTVs. One basis for such a method is Blended Design. This method is able to cope with market uncertainties in the early stages of ship design by expanding knowledge when design freedom is still high by combining market forecasts for offshore wind farms with multiple vessel designs. An uncertainty model then evaluates the financial performance of the vessels in the market, allowing designers to explore the performance on basic main dimensions of an offshore wind installation vessel. The main limitations of this method are that it is not able to optimize on environmental performance and evaluate the financial impact of alternative fuels. Due to growing concerns about climate change, Ulstein has seen an increase in requests for the use of alternative fuels in ship designs. For this research, methanol, ammonia and liquid hydrogen are being investigated as these alternative fuels are considered future-proof. The use of alternative fuels in ship design involves some adjustments to the Blended Design method. Due to the different gravimetric and volumetric densities of these alternative fuels, this has implications for the endurance of the ship design and the amount of cargo the ship can carry. Changing system and installation requirements and varying fuel costs also drastically alter the financial performance of alternative fuels on ship designs. The proposed methodology accounts for these changes and quantifies alternative fuel emissions by converting them to CO2-equivalent emissions. In this way, other greenhouse gases such as CH4 and N2O are also included in this metric. The environmental performance is then expressed in the EEXI-equivalent: the amount of CO2-e emitted by the ship design per tonmile. The EEXI-e index makes it possible to compare the various alternative fuels in terms of their environmental performance on the same basis. In this work the EEXI-e method is combined with the original Blended Design method and the method is adapted to include alternative fuels. This makes it possible to evaluate the environmental performance and associated financial impacts of different alternative fuels. Because financial and environmental performance are now linked, it is possible to examine the impact of different ranges of carbon taxes. The case study results presented in this thesis show that the carbon tax has a large impact on the financial performance of the ship when it is applied. When enforced, the choice of an alternative fuel system becomes more attractive. The proposed method has provided a guide to ship designers to make better decisions about the main dimensions of a ship at an early stage of ship design. In addition, the method can provide much-needed insight in the selection of alternative fuels by evaluating the financial and environmental performance of alternative fuel systems.

The offshore wind market is rapidly growing, resulting in increasing wind turbine sizes, increasing distances to port, and a shift to deeper waters. A literature study in this thesis shows that existing wind turbine installation vessels, vessels under construction, and innovative concepts will not be able to install next-generation turbines or that they would have installation bottlenecks, making them cost-inefficient. This goes against the goal of decreasing the Levelized Cost of Energy (LCOE) of wind energy, to ensure that offshore wind stays competitive with other energy sources, enabling the energy transition. There is thus a gap between future demand of offshore wind installation vessels and current and near-term solutions. The research proposes a new floating monohull vessel concept, called Moonshot, to fill this gap. Moonshot will thus be different than traditional jack-up or semi-submersible installation vessel options. In this research, various design strategies were analyzed. Based on the findings, a design strategy is developed to design and analyze Moonshot. A combination of Ulstein Design and Solution B.V.’s Controlled Innovation process and Blended Design were used and extended to develop this new concept. First, the important functions and design aspects of the design were established using Controlled Innovation. Blended Design was then used to create a design space of the design configurations and to explore multiple market scenarios to establish optimal ship parameters for further development. As part of the research, the existing design process and model were modularized and new features were developed to suit wind turbines, assess seakeeping behavior, and explore the design space of the future wind turbine installation vessel. The results of this research aim to elucidate optimal design parameters across certain market scenarios. Results show how optimizing the design for financial performance, seakeeping behavior, or a combination of the two, influences the optimal design point. With the optimal design ranges, the initial design parameters for the next stage in the design of Moonshot are established. Finally, Blended Design is used to benchmark Moonshot against existing wind turbine installation solutions to assess its performance. A version of Moonshot is developed as a direct competitor for the largest jack-up design available, the NG-20000X. Benchmarking with the jack-up, an SSCV, and Huisman’s WIV concept showed that Moonshot would be a more efficient solution, capable of installing a larger number of turbines per year at a considerably lower cost per megawatt compared to the other solutions. In summary, this research concludes Moonshot as an innovative concept to address the evolving challenges of offshore wind turbine installation. By combining innovative design strategies, extensive assessment, and optimization, Moonshot emerges as a promising contender in the quest for effective and cost-efficient installation solutions for offshore wind.