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The Mobile Offshore Base (MOB) is a large, self-propelled, floating, pre-positioned ocean structure formed of three to five modules and reaching up to 1,500 meters in length. The alignment of the modules is maintained through the use of thrusters and/or connectors. A simulation framework has been used to provide evaluation of different control strategies. We have conducted experiments in which three 1:150 scale modules are kept aligned by pivoting thrusters and form a miniature runway. This paper addresses lessons learned in the course of the MOB project.

The mobile offshore base (MOB) will consist of a number of large semi-submersible modules connected together to form a runway approximately 2 km long. In order to conduct model-based testing of such a system with reasonably sized models, it is necessary to use models with a very small scale. In this paper, we outline the design and characterization of a 5 cm diameter azimuthing thruster unit designed for use on a 1:150 scale model of a MOB module. Experimental results are presented regarding thrust performance, thrust response dynamics, thrust level stability and repeatability, effects of pontoon proximity and azimuth angle relative to pontoon, and effects of advance velocity. The results indicate that the thruster performs well and is suitable for use in model-testing applications.