In the current energy market, where increasing demand for renewable energy is met with larger turbines which require larger installation vessels, understanding operational limits of such vessels becomes invaluable. For the installation of wind turbine generators at great heights, a stable working platform is offered by jack-up (JU) vessels, which use legs to elevate the hull and thus crane of the vessel above the waves. The operation taken into consideration is the preloading process where load is increased on the legs to ensure enough foundation capacity for later operations such as lifting of wind turbine generators. Traditionally, vessels have only been positioned above flat seabeds, but with the increased demand in the wind sector, unfavorable locations with sloped seabeds also need to be considered.
In order to capture global behaviour of a JU on a sloped seabed, two modelling methods are combined to create a framework; soil-structure interaction and structural finite element model. This framework implements a sub structuring approach by cutting and simulating a single leg on a sloped seabed using soil-structure interaction modelling. The results of the first method are foundation stiffness values and reaction loads during preloading of the JU while the second method takes those results as input to calculate internal loads of the JU.
The results show that the proposed framework is able to fulfill the task of combining two models and obtain meaningful results that can inform the JU during preloading phase. Then with this framework, the results show that sloped seabed induces an extra set of moments and lateral loads due to the asymmetric seabed causing an eccentric reaction load. These moments are then redistributed through the JU to other legs and their footings.
These results imply that for a JU on a sloped seabed, a framework combining geotechnical and structural domains can be applied to show the increased load due to the sloped seabed. Additional to the results, a sensitivity study is implemented for a variation of soil type and soil-structure geometry, the latter providing a more realistic seabed slope and larger reaction loads.

This report will give an in depth view on the technical feasibility of placing an offshore platform from which watersports can be practiced in the waters surrounding the island of Bonaire. The feasibility research is done by appointment of two entrepreneurs on the island of Bonaire. The report will give an answer to the research question: Can an offshore floating platform, aimed at fast watersports, be built as sustainable as possible within the context of Bonaire? This research question can be divided into multiple sub-questions, being: 1. What is the context of Bonaire? 2. What is, for this report, the definition of sustainability? 3. What facilities are needed on the platform? 4. How can 100% renewable energy be generated for the platform? 5. What would such a (conceptual) platform look like? To answer these questions, the method as described in Kossiakoff (2011) is used. This method gives structure to the design of a system that has not been used before, but tries to combine older systems in new innovative ways. From this method, three important stages in the design process have been identified: The needs analyses, the concept exploration and the concept definition. This report follows that structure, starting with the chapter: Needs analyses. In this chapter, the report answers the first two sub-questions. The context of Bonaire can be described as: an island with opportunities for every-one, but the local environment suffers from the exponential growth of people and tourists that visit the island. For the second sub-question the definition of sustainability has been placed within this context of Bonaire, leading to a specialized definition of sustainability. This definition combined with the requirements of the clients has lead to a valid need for the platform. The concept exploration, gives options to answer those needs. It does so by researching a broad range of possible facilities for the platform. This broad research eventually leads to a morphological map from which 3 realistic and 1 futuristic concepts are designed. In the concept definition these 3 realistic concepts have been tested by an MCA resulting in one concept that has been worked out for various components, thus answering sub question 5. From this worked out concept, a conclusion is written in where the main conclusion is that an offshore platform aimed at fast water sports van be build sustainable within the context of Bonaire if the clients are able to make some consensus in there plans and the way they will use the platform. Finally, considering the sustainability of the proposed platform, it can be concluded with current technologies it is hard to build a platform without emissions, negative effects or any hidden impact. However, if the schedule and plans of the clients where to change towards a more ’nature dependent’ schedule (so taking peak energy generation into account). The platform could set an example and can even be a global ’first’ when it comes to making the practice of watersports more sustainable.