Print Email Facebook Twitter Stern vs Side installation of Monopiles from floating vessels Title Stern vs Side installation of Monopiles from floating vessels: Objective comparison methods to make a distinction between side and stern installation of future Monopiles Author Rosenboom, Bas (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Offshore and Dredging Engineering; Huisman Equipment BV) Contributor Ummels, B.C. (graduation committee) van der Stap, A.C.M. (mentor) Dijkstra, Jeroen (graduation committee) Degree granting institution Delft University of Technology Programme Offshore and Dredging Engineering Date 2022-07-22 Abstract 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 investigatedusing 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 onsensitivity, 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 beenexecuted. 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. Subject MonopilesWindInstallationFloating vesselEquipment To reference this document use: http://resolver.tudelft.nl/uuid:470d316e-e4f3-440b-bfec-3c67d1996a76 Part of collection Student theses Document type master thesis Rights © 2022 Bas Rosenboom Files PDF Repository_Stern_vs_Side_ ... enboom.pdf 9.79 MB Close viewer /islandora/object/uuid:470d316e-e4f3-440b-bfec-3c67d1996a76/datastream/OBJ/view