Large yacht hull measurement by integrating optical scanning with mechanical tracking-based methodologies

In the shipbuilding industry, the manufacturing of large yacht hulls is a complex process. Metal hulls are traditionally manufactured by welding pre fabricated large steel panels to form the external superstructure. A surface finishing process is then carried out in order to obtain a final target surface having a smooth curvature. The methodologies manly rely on manual processes based on the measurement of the as built hull shape through simple testing instrumentation. Well-experienced workers are required, and a great amount of time is usually wasted, thus affecting the overall shipyard competitiveness. This paper introduces a methodology for automating the measurement process of as built hull yacht shapes. The methodology, which is based on the integration of a robotic system with an optical scanner, provides accurate non contact 3D full field measurements of the hull surface. The placement of the robotic system around the hull shape is determined by a laser total station thus allowing the automatic multi view data registration into a common reference frame. The proposed approach represents the basis for the automation of the whole surface finishing process of large yacht hulls. In this paper, the methodology has been tested by measuring a large broadside area of a 59 m hull assembled within a shipyard.