System Based Design for Mobile Offshore Units
MetadataShow full item record
- Institutt for marin teknikk 
This thesis seeks to investigate the possibilities of adapting the method of system based ship design developed by Kai Levander (2012), to be applied to MOU s. Design is the creation of a plan or construction of an object. The term design can relate to either a product or a process. This thesis focuses on the process of designing the initial concept design by adapting a method previously not applied to MOU s.Ship design is a well-developed process and has previously been perceived as an iteration process with a fixed number of phases that leads to the final detailed design. Those phases are concept design, preliminary design and detailed design (Taggart, 1980). Levanders s SBD approach utilizes the information from the mission requirements and mission analysis to develop an initial design before the iterative process. The iterating process can then be started with a solution closer to the optimal solution. For adapting this method to MOU s, all main function was developed into a functional hierarchy that connects the supporting equipment and systems with the main function. With this method, the specifications for the lower levels of the hierarchy could be connected through driving parameters of the mission specifications. The different types of MOU all serve the same main purpose; to support a deck above the water line. However, their structural differences makes each type suitable under different conditions. A structural comparison of the different main types of MOU was then developed. For the adaptation of the SBD method, an additional division of the system hierarchy was performed. This additional level divided the MOU systems in scalable and non-scalable systems. The next level in the system hierarchy would then be task related systems and platform systems. For the scalable systems, the driving parameters from the initial mission specifications are used to estimate main deck area, volumes and weights. For the non-scalable systems, needed specifications were found from gathered statistics such that standard areas, volumes and weight inputs could be taken into account. The method gives an initial main deck area requirement, volume estimations for tanks and voids, initial VDL and an initial weight estimation of the topside structure. Further, a method for establishing a deck layout for all types of structures was developed on the basis of the transportation flow and workflow on a MOU (Yue, 2009). The process of the initial sizing and geometrical definition of the hull structure based on initial transverse stability and sea keeping was then briefly described. The method developed is illustrated to a case specific example, where simplified mission specifications serves as the input variables. The case was mad for a well drilling MOU, and the initial structure type was a semi-submersible unit. The results from the case From the case results, it is clear that the main deck area and the VDL was larger than any comparison units were. The topside weight is underestimated. With the necessary assumptions done in this paper, the SBD approach gives the required parameters to be able to perform the initial designs of MOU.